T R Seshadri
Articles written in Proceedings – Section A
Volume 1 Issue 12 June 1935 pp 887-890
The Cambodia cotton flowers (
Volume 2 Issue 5 November 1935 pp 490-496
The flower petals of the Uppam cotton plant (
Volume 3 Issue 1 January 1936 pp 38-42
Brucine sulphate has been shown to be a good internal indicator for titrations with dichromate and in certain respects superior to diphenylamine. The colour change from green to bright red at the end point is much more pronounced than the change from green to blue in the case of diphenylamine.
It has been shown that in titrations with potassium permanganate solutions, the disturbing effects due to the presence of hydrochloric acid may be obviated by using brucine as an internal indicator. The presence of ferric iron has not been found to interfere with the sharpness of the end point.
The use of this indicator in the analysis of chromium ores and in the estimation of organic matter in soils by the Schöllenberger method has been indicated.
Volume 3 Issue 1 January 1936 pp 293-296
A rapid and efficient method has been found for preparing coumaric acid and 4-methylcoumaric acid from coumarin and 7-methylcoumarin respectively by treatment with mercuric oxide in the presence of cold alkali. 5-nitrocoumaric acid is not produced in the cold and is formed only by boiling the mixture of 6 nitrocoumarin, mercuric oxide and alkali. The action of cold alkali and mercuric acetate or of hot alkali and mercuric oxide on coumarin yields mercurated coumaric acids. From these pure coumaric acid can be produced by using ammonia and hydrogen sulphide.
Volume 3 Issue 4 April 1936 pp 293-296
A rapid and efficient method has been found for preparing coumaric acid and 4-methylcoumaric acid from coumarin and 7-methylcoumarin respectively by treatment with mercuric oxide in the presence of cold alkali. 5-nitrocoumaric acid is not produced in the cold and is formed only by boiling the mixture of 6 nitrocoumarin, mercuric oxide and alkali. The action of cold alkali and mercuric acetate or of hot alkali and mercuric oxide on coumarin yields mercurated coumaric acids. From these pure coumaric acid can be produced by using ammonia and hydrogen sulphide.
Volume 4 Issue 1 July 1936 pp 54-58
A preliminary examination, using a small sample of the flower petals of the Karunganni (
Volume 4 Issue 2 August 1936 pp 157-161
Coumaric acids which ordinarily form hydroxystyrenes on heating yield the corresponding coumarins when heated in the presence of mercuric oxide or chloride. The scope of the use of concentrated sulphuric acid and alcohol saturated with hydrogen chloride for producing
Volume 4 Issue 2 August 1936 pp 162-169
In methyl alcoholic solution coumarin reacts with mercuric acetate to form 3:6:8-triacetoxymercuri-4-methoxymelilotic anhydride. By the action of sodium hydroxide and hydrogen sulphide β-methoxymelilotic acid is obtained from it and by the action of bromine 3:6:8-tribromocoumarin. 7-methylcoumarin behaves similarly giving a trimercury compound. 6-nitrocoumarin forms 3:8-diacetoxymercuri-6-nitro-4-methoxymelilotic anhydride which, with alkali and hydrogen sulphide, gives 5-nitrocoumaric acid and with bromine 3:8-dibromo-6-nitrocoumarin. It is therefore established that mercuric acetate reacts with the double bond in these coumarins and further mercurates the benzene ring in positions 6 and 8 if they should be free. Mercuric chloride adds on to the double bond in coumarin and 7-methylcoumarin. The reactions of these addition products have been studied. 6-nitrocoumarin does not react with this reagent.
Volume 4 Issue 6 December 1936 pp 630-638
When mercuric acetate reacts with coumarinic acid in cold aqueous solution it adds on to the double bond and mercurates the benzene ring in positions 3 and 5. When the product is dissolved in sodium hydroxide the addenda get eliminated so that 3 ∶ 5-diacetoxymercuri-coumaric acid is produced on acidification. These compounds yield pure coumaric acid on being decomposed with hydrogen sulphide in alkaline solution. 5-Nitrocoumarinic acid adds only at the double bond and does not get mercurated. The product therefore yields the nitrocoumaric acid easily on dissolving in aqueous alkali and subsequently acidifying the solution.
In methyl alcoholic solution mercuric acetate adds on to the double bond in coumaric acids and their esters and mercurates positions 3 and 5 if they should be free. The constitution of these compounds has been established by treatment with bromine in glacial acetic acid and by examination of the action of caustic alkali on the bromocompounds. They give rise to brominated coumarilic acids.
Volume 5 Issue 3 March 1937 pp 249-256
The methyl ethers of the
Volume 5 Issue 4 April 1937 pp 351-356
The components of the seeds have been obtained in a greater number of fractions which are fairly homogeneous by using a new method of analysis. It consists in extracting the entire seed with ether in the cold thereby removing all the components of the pericarp. This portion has been separated as the volatile essential oil, non-volatile terpenoid oil and alkali-soluble resin. The rest of the seed is crushed and extracted with petroleum ether. This gives rise to a good yield of the bitter principles as crystalline solids and the fixed oil in a pure condition. The physical and chemical properties of the pure fixed oil and its component acids and certain properties of the terpenoid oil have been studied in detail. A sterol (Phytosterol) in the form of its acetate has been isolated from the unsaponifiable portion of the fixed oil. The residual cake contains only traces of the bitter solid, a good percentage of proteins and mineral matter and is suitable as a feeding stuff and manure. Some of the fractions have definite action on the skin.
Volume 5 Issue 4 April 1937 pp 357-364
Herbacitrin, the new flavonol glucoside obtained from
Volume 6 Issue 1 July 1937 pp 12-15
An attempt has been made to fix the position of the glucose residue in gossypitrin by methylation with diazomethane and hydrolysis of the product. It has been found that methylation is incomplete, one hydroxyl group remaining unaffected, and thereby giving after hydrolysis a tetramethyl-gossypetin. This compound probably has the two hydroxyl groups in the 5 and 7 positions.
Volume 6 Issue 2 August 1937 pp 112-118
When umbelliferon condenses with malic acid two isomeric compounds are formed. The angular coumarino-7: 8-α-pyrone is the major product (95%) and its constitution is established from its preparation from umbelliferon-8-aldehyde by the Perkin's reaction. The second compound which should be the linear coumarino-7: 6-α-pyrone is formed in a very small yield only (5%). Under the same conditions 4-methylumbelliferon produces only one compound whose constitution as 4-methylcoumarino-7: 8-α-pyrone is arrived at from its independent synthesis from 4-methylumbelliferon-8-aldehyde. The constitution of this aldehyde is deduced not only from analogy but also from its reduction to 4: 8-dimethyl-7-hydroxycoumarin which has been prepared from 2-methylresorcinol and ethylacetoacetate. 4-Methylumbelliferon and ethylacetoacetate also give only one compound which is given the constitution 4: 4′-dimethylcoumarino-7: 8-α-pyrone. This compound has been found to be produced in good yield from resorcinol and ethylacetoacetate in the presence of alcoholic hydrogen chloride.
It is concluded that the angular isomer is the one invariably and most predominantly formed though the formation of the linear variety is not altogether precluded.
Volume 6 Issue 2 August 1937 pp 148-153
Volume 6 Issue 4 October 1937 pp 238-242
By the action of bromine on coumaric, 4-methylcoumaric and 5-nitrocoumaric acids in boiling glacial acetic acid solution 3∶6∶8-tribromocoumarin, 3∶6∶8-tribromo-7-methylcoumarin and 3∶8-dibromo-6-nitrocoumarin have been obtained in good yield. The primary products are the dibromides of the bromo-compounds produced by the addition at the double bond, subsequent substitution in the nucleus and final ring closure. Hydrogen bromide gets slowly removed during the boiling and during the subsequent crystallisations so as to yield the above-mentioned bromocoumarins. The best method for this however is to use cold alcoholic potash. Small quantities of the lower bromination products are also produced as by-products.
Volume 7 Issue 1 January 1938 pp 8-12
The behaviour of 7-hydroxy-coumarin indicates that there exists a double bond between 7 and 8 positions. But 7-hydroxy-4: 8-dimethyl-coumarin couples with diazocompounds and undergoes mercuration in the benzene nucleus. Its acetyl derivative undergoes the Fries migration and its allyl ether the Claisen transformation. It is therefore concluded that the nuclear double bonds are not fixed and are capable of assuming alternative positions.
Volume 7 Issue 3 March 1938 pp 179-185
From the seeds of
Volume 7 Issue 4 April 1938 pp 296-303
Volume 7 Issue 5 May 1938 pp 312-318
The action of mercuric acetate on the methyl ethers of coumarinic and coumaric acids and their 5-nitro derivatives has been described. The first two undergo addition at the double bond as well as mercuration and the compounds have the carboxylic formula. The nitrocoumarinic and coumaric acids undergo addition only and yield the carboxylic form in the cold and the anhydro form on heating. When the addenda are eliminated by the action of dilute hydrochloric acid the change is accompanied by geometrical inversion from
Volume 8 Issue 4 October 1938 pp 214-219
The methylation of resacetophenone and its ω-methoxy derivative using methyl iodide and methyl alcoholic potash has been studied. The former gave 2-hydroxy-3-methyl-4-methoxyacetophenone the constitution of which was established by demethylation to 3-methylresacetophenone and comparison with a specimen prepared from 2-methylresorcinol. In the same way ω-methoxyresacetophenone gave 2-hydroxy-3-methyl-ω: 4-dimethoxyacetophenone which was subsequently converted to 3: 7-dimethoxy-8-methylflavone. The identity of this flavone was proved by its synthesis from 2-methyl-resorcinol.
It is concluded that under the above conditions resacetophenone undergoes nuclear methylation in the 3-position and that the hydroxyl group in the 4th position gets etherified.
Volume 8 Issue 5 November 1938 pp 519-523
The Raman spectrum of coumarin in the solid state and when dissolved in various solvents has been examined with reference to (1) the C=C and (2) the C=O frequencies. Of the three frequencies belonging to (1) which are fairly constant throughout, the two lower ones represent the aromatic double bonds of the benzene ring and the third represents the ethylene double bond of the pyrone ring. The C=O frequency is considerably low in the solid state as well as in the solutions with certain polar solvents. This is attributed to the weakening of the C=O bond by the formation of hydrogen bonds through co-ordination.
Volume 9 Issue 1 January 1939 pp 1-6
7-Allyloxyflavone undergoes Claisen transformation to form 8-allyl-7-hydroxyflavone, the constitution of which is established from its synthesis from 3-allyl-resacetophenone. The bond distribution should therefore be as in (I). However 8-alkyl substituted derivatives undergo coupling with diazotised
Volume 9 Issue 1 January 1939 pp 7-9
Starting from 3-methoxy-7-hydroxyflavone, 2-methyl-3-methoxy-7-hydroxychromone and 7-hydroxyflavone aldehydes have been prepared. In these compounds the aldehyde groups occupy the eighth positions. By the action of sodium acetate and acetic anhyrdide the corresponding chromono-and flavono-α-pyrones have been synthesised.
Volume 9 Issue 1 January 1939 pp 10-16
A large number of organic compounds belonging to different groups have been studied in regard to their behaviour on the surface of water. The influences of the various groups—COOH, >C=O, −NH2, etc. in a substance on its behaviour on the water surface are discussed.
Percentage lowering of surface tension of aqueous solutions of a number of typical compounds are recorded and the results compared with their behaviour on the water surface.
Combination movements exhibited by the pairs phenylacetic acid— camphor and
Volume 9 Issue 1 January 1939 pp 22-28
The action of mercuric acetate in methyl alcoholic solution on (1) umbelliferone, (2) 4-methylumbelliferone and (3) 4: 7-dimethylcoumarin has been investigated. With umbelliferone addition at the double bond and substitution in positions 6 and 8 take place whereas in the case of its 4-methyl derivative position 8 alone is mercurated to yield a monoacetoxymercuri-compound. In regard to the last compound the reaction stops with addition at the double bond and mercuration of the 6th position, the position 8 escaping the attack of the reagent. It is concluded that owing to the influence of the substitutent groups the reactivity of the three active centres of the coumarin molecule are differently affected.
Volume 9 Issue 2 February 1939 pp 121-127
A detailed chemical examination of the stems and leaves of
Volume 9 Issue 2 February 1939 pp 133-135
The action of diazomethane on herbacetin yields 3∶7∶8∶4′-tetramethylherbacetin. The pentamethyl ether is obtained by the further methylation of the above tetramethyl compound with dimethyl sulphate and sodium hydroxide in aqueous acetone medium.
Volume 9 Issue 3 March 1939 pp 177-180
The constitution of Gossypitrin has been established as the 7-glucoside of the flavonol Gossypetin by complete methylation of the glucoside through the acetyl derivative and the isolation of 7-hydroxy-3: 5∶8∶3′∶4′-pentamethoxyflavone by the hydrolysis of the above methylated glucoside. The acetyl derivative of the pentamethyl gossypetin has also been prepared.
Our thanks are due to Dr. S. Rangaswami for help in connection with the microanalysis of the compounds.
Volume 9 Issue 3 March 1939 pp 259-264
2-Methyl-3-methoxy-7-hydroxychromone-8-aldehyde formed a sodium derivative which readily condensed with bromoacetic ester to form the corresponding carbethoxy-methyl ether. This reaction did not take place satisfactorily with 3-methoxy-7-hydroxyflavone-aldehyde. The condensation was, however, smoothly effected in boiling benzene solution in the presence of potassium carbonate. When hydrolysed with aqueous potassium hydroxide, simultaneous ring-closure took place to yield 3-methoxyflavono-7: 8-furan-α-carboxylic acid which is considered to be karanjin-α-carboxylic acid.
Volume 9 Issue 4 April 1939 pp 328-332
Methylation of naringin by means of methyl iodide and potassium carbonate in acetone medium opens out the pyrone ring and methylates all the phenolic hydroxyl groups. The product on hydrolysis yields 2 ∶ 6 ∶ 4′-trimethoxy-4-hydroxychalkone. It is therefore concluded that in naringin the sugars, glucose and rhamnose exist as a disaccharide unit attached to position 7.
Volume 9 Issue 4 April 1939 pp 365-369
The constitution of Herbacitrin is established as the 7-glucoside of Herbacetin by methylating the glucoside through the acetyl derivative and isolating 7-hydroxy-3: 5: 8: 4′tetramethoxy flavone from the hydrolysis of the methylated glucoside. Similarly, the constitution of Quercimeritrin is confirmed as the 7-glucoside of Quercetin.
Volume 9 Issue 6 June 1939 pp 526-530
The formation of azo-dyes using one and more than two molecular proportions of diazotised
Volume 10 Issue 1 July 1939 pp 1-5
Mercury compounds of succinimide and pthalimide have been obtained easily and in a pure condition by treating the respective imides with mercuric acetate in alcoholic solution. Carbamide (urea) forms two compounds when it reacts with mercuric acetate in different proportions: (I) Mercury carbamide and (2) Di-acetoxymercuri carbamide. The preparation of mercury acetamide is best effected only through the use of mercuric oxide. When mercuric acetate in alcoholic solution is employed, acetoxymercuri acetamide is formed.
Volume 10 Issue 1 July 1939 pp 6-8
3-Benzoyl-7-hydroxyflavone has been prepared and its properties have been studied.
Volume 10 Issue 2 August 1939 pp 65-70
A method of extracting Karanjin in good yield from Pongamia oil is described. Karanjin is only faintly bitter and is found to be useful for the treatment of leucoderma. A method of hydrolysis of Karanjin giving rise to a good yield of Karanjic acid has been found. It has been shown that Pongamia oil contains potassium in some form of chemical combination. By the action of mercuric acetate, Karanjin yields a di-acetoxy-mercuri compound.
Volume 10 Issue 2 August 1939 pp 96-103
A detailed chemical examination of the Indian senna leaves has been made. The ash has been analysed. An aqueous extract of the leaves has been found to contain a good amount of calcium salts. A petroleum ether extract yields senna wax consisting of free myricyl alcohol admixed with regular wax. Methods have been worked out for obtaining the flavonol and authraqui one group of compounds separately in the most convenient manner and in the best yield. The flavonol portion consists of iso-rhamnetin and kæmpferol in more or less equal quantities, whereas the anthraquinone portion contains mostly rhein along with small quantities of emodin.
Volume 10 Issue 4 October 1939 pp 267-274
The acetyl derivatives of coumaric, 4-methylcoumaric, 5-nitrocoumaric, psoralic and isopsoralic acids have been prepared and their behaviour studied under conditions which bring about
Volume 10 Issue 4 October 1939 pp 307-316
The Raman spectra of the phenyl esters of cinnamic and benozic acids have been studied and those of the methyl and ethyl esters of the above acids along with that of phenyl acetate have been reinvestigated. From the above data and those obtained by other workers relating to alkyl and phenyl esters and some other carbonyl compounds the C=O frequencies have been tabulated. It is noted that the phenyl group attached directly to the carbon of the C=O group as in esters of aromatic acids and in aromatic ketones, etc., markedly lowers the carbonyl frequency whereas the same group attached to the oxygen atom of the COO group definitely enhances the frequency. These facts are explained from considerations of electromeric polarisation and resonance.
Volume 11 Issue 1 January 1940 pp 23-27
Experiments have been conducted with a view to test if the progress of oxidation by mercuric acetate could be followed by weighing the amount of mercurous acetate precipitated from time to time. This procedure has been found to be not feasible since complications set in owing to the solvent also undergoing oxidation induced by the presence of other substances. It has been found that most compounds containing -CHOH group produce mercurous acetate in methyl alcoholic solution and the oxidation products could be identified. Convenient methods for the preparation of benzil, quinhydrone, quinone and mercurous acetate in a pure condition in the laboratory are described.
Volume 11 Issue 1 January 1940 pp 32-38
Raman spectra of esters containing the benzyl group, (i) benzyl esters of various acids and (ii) esters of phenyl acetic acid derived from different alcohols, have been investigated. Data relating to other carbonyl compounds such as ketones, aldehydes and acid chlorides have been collected. In regard to its influence on the C=O frequency the benzyl group is found to resemble closely alkyl groups and to differ markedly from the phenyl. This confirms the views already expressed in Part II and establishes that the C=O group is influenced mainly by the electromeric effect. The introduction of an additional CH2 prevents the transmission of this effect.
Volume 11 Issue 3 March 1940 pp 206-211
Starting from 7-hydroxy-coumarins and flavones the chloracetoxy compounds have been prepared and these have been converted into coumarino-7∶8-furanones and flavono-7∶8-furanones by means of the Fries reaction. Their properties have been studied and their benzylidine and acetyl derivatives obtained.
Volume 11 Issue 4 April 1940 pp 289-297
The action of mercuric chloride and mercuric acetate on the alkaloids quinine and cinchonine has been investigated with a view to prepare organomercury compounds. The properties and constitutions of the compounds have been studied. Mercuric chloride forms combinations with the basic nitrogen atoms of the alkaloids whereas with mercuric acetate it is posible to produce compounds by addition at the ethylenic double bond. Some of these can be conveniently employed for therapeutic purposes.
Volume 11 Issue 5 May 1940 pp 424-428
Raman effect and chemical constitution - Influence of constitutive and other factors on the double bonds in organic compounds Part IV. The frequency of the ethylenic double bond in unsaturated carbonyl compounds
The Raman spectra of cinnamyl alcohol and cinnamyl acetate are re-investigated and their frequencies compared with those of ethyl cinnamate. A great similarity between the spectra of all these substances is observed. The higher C=C and C=O frequencies in cinnamyl acetate and allyl acetate as compared with ethyl cinnamate and ethyl acrylate is explained as due to the existence of resonance in the latter. It is pointed out that when comparisons are effected carefully the C=C and C=O bonds mutually weaken each other when they exist in conjugation.
Volume 11 Issue 6 June 1940 pp 505-511
Convenient methods have been worked out for the isolation of the bitter principles of the peels, rags and the seeds of pamparapanas (Indian Shaddock). The first two contain naringin to the extent of 0 13 and 1% respectively whereas in the seeds naringin (0·15%) and limonin (about 0·6%) are found to be the most important bitter components besides small amounts of isolimonin. Some properties of limonin and isolimonin have been studied.
Volume 12 Issue 4 October 1940 pp 367-371
The component fatty acids of the oil obtained from the seeds of Indian shaddock have been examined. It contains very little of unsaponifiable matter and consists of the glycerides of palmitic acid 20·7%, stearic acid 15·3%, oleic acid 55·46%, linolic acid 8·07% and linolenic acid 0·48%.
Volume 12 Issue 4 October 1940 pp 375-380
Volume 12 Issue 5 November 1940 pp 466-471
Volume 12 Issue 5 November 1940 pp 477-480
A new method of isolating butein and butin from the flowers of
Volume 12 Issue 6 December 1940 pp 495-497
By the action of methyl iodide and potassium carbonate, quercetin underwent complete methylation, while herbacetin and gossypetin yielded 3∶7∶8∶4′-tetramethyl ether and 3∶7∶8∶3′∶4′-pentamethyl ether respectively. This reagent, therefore, resembles diazomethane in the methylation of the naturally occurring flavonols.
Volume 12 Issue 6 December 1940 pp 498-506
The lichen acids, atranorin and lecanoric acid obtained from
Volume 12 Issue 6 December 1940 pp 519-531
The conditions for the production of paper pulp from rice straw by the alkali process have been investigated. About 22% of soda on the weight of the straw used in 3% solution, a temperature of 100–05°C. and a cooking period of 3 hours have been found to be satisfactory. With a view to effect economy in alkali the mother liquor has been used in a subsequent double boiling process yielding paper pulp of good quality. In a straw having cellulose (Cross and Bevan) 37·5% the yield of paper pulp is about 44%. The characteristics of the pulp are described in detail.
Volume 13 Issue 3 March 1941 pp 199-202
The isolation of a new phenolic compound, ‘Montagnetol’ from the lichen
Volume 13 Issue 3 March 1941 pp 221-232
The general chemical composition of the roots of
Volume 13 Issue 4 April 1941 pp 255-258
7-Hydroxy-5-methylcoumarin has been synthesised from orcylaldehyde by condensation with diethyl malonate and by subsequent removal of the carbethoxyl group. The compound obtained from orcinol and malic acid by the method of Pechmann has been shown to be identical with the above product and hence it is concluded that in this case orcinol exhibits reactivity of the β-position.
Volume 13 Issue 4 April 1941 pp 316-321
A number of umbelliferone derivatives with acetyl, benzoyl, carbethoxyl or carboxyl groups in the 3-position have been prepared of which 6 are new. The fluorescence exhibited by these has been studied and the results are discussed.
Volume 13 Issue 5 May 1941 pp 395-398
Butrin has been obtained by a simple method and in good yield from the flowers of
Volume 13 Issue 5 May 1941 pp 399-403
The roots of the
Volume 13 Issue 5 May 1941 pp 404-410
The methyl ether of karanjic acid has been converted into 5-ω-methox acetyl-4-methoxycoumarone which is found to be identical with the meth ether of the ketone obtained by the hydrolysis of karanjin with alka Following a similar procedure 5-ω-methoxyacetyl-4-hydroxycoumaroi has been synthesised from karanjic acid and this yields karanjin when col densed with benzoic anhydride and sodium benzoate. Thus all the stages the complete synthesis of karanjin have been accomplished.
Volume 13 Issue 6 June 1941 pp 510-518
4-O-methyl ether of resorcylic aldehyde has been condensed with (I) acetophenone, (II) ω: 4-dihydroxy acetophenone, (III) ω∶3∶4-triacetoxy-and (IV) ω∶3∶4∶5 tetra-acetoxy-acetophenone to form pyrilium salts. Their properties and reactions are described. The first compound which has no hydroxyl groups in it undergoes change into the corresponding chalkone when its solution is treated with sodium acetate or when largely diluted with water. The reverse reaction takes place also rapidly in acid solution. The other compounds resemble closely pelargonidin, cyanidin and delphinidin though they exhibit a comparatively marked poverty of colour in solutions.
Volume 14 Issue 1 July 1941 pp 29-34
On treatment with diazomethane, butrin gives rise to a monomethyl ether which yields on hydrolysis with acids a mixture of 4′-O-methylbutin and 4′-O-methylbutein, the latter being the major component. The constitutions of these two products have been established by alkaline oxidation, yielding isovanillic acid and comparison with synthetic samples. It is, therefore, concluded that butrin is 3′: 7-diglucoside of butin, and thus it is the first instance of a glycoside to contain the sugar residues in two different positions amongst the group of anthoxanthins and also the first instance to carry a sugar group in the side phenyl nucleus amongst both anthoxanthin and anthocyanin pigments.
Volume 14 Issue 2 August 1941 pp 93-99
The existence of resinol in the petrol-soluble portions of
Volume 14 Issue 2 August 1941 pp 105-111
The colouring matter of the flower petals of
Cannabiscetin forms a hexaacetate and a hexamethyl ether. It is a flavonol exhibiting similarities with gossypetin and herbacetin particularly in regard to alkali colour reactions and gossypetone reaction. It yields gallic acid on being subjected to alkali fission, its methyl ether producing trimethyl gallic acid. It is, therefore, concluded to be 3:5:8:3′:4′:5′ hexahydroxy flavone.
Volume 14 Issue 3 September 1941 pp 265-269
The final constitution of cannabiscitrin has been established. It is a monoglucoside of the flavonol cannabiscetin, carrying the sugar group in the side phenyl nucleus in the 3′-position. This has been arrived at from the following considerations:—It gives the gossypetone reaction and after complete methylation and hydrolysis, it yields a pentamethyl cannabiscetin which on decomposition produces 4∶5-dimethyl gallic acid. The same acid is also obtained by first decomposing cannabiscitrin with alkali, and then subjecting the products to methylation and subsequent hydrolysis. Thus the glucoside belongs to an unusual type and resembles butrin.
Volume 14 Issue 3 September 1941 pp 289-296
Quercetagitrin, a monoglucoside of quercetagetin, has for the first time been isolated from the flowers of the African Marigold (
Volume 14 Issue 3 September 1941 pp 297-306
A survey of past work on the nuclear methylation and ethylation of resorcinol and phloroglucinol derivatives is given and a mechanism for this reaction suggested. The nuclear methylation of β-resorcylic aldehyde has now been carried out giving rise to a good yield of the product (A). Its constitution as 4-methoxy-3-methyl-2-hydroxy benzaldehyde has been established in two ways: (i) A sample of 4-methoxy-3-methyl-2-hydroxy benzaldehyde was prepared according to the synthetic method of Jones and Robertson and compared with (A). (ii) The corresponding coumarin was prepared from (A) and was identified as 7-methoxy-8-methyl coumarin by comparison with the compound obtained by independent synthesis, starting from 2-methyl-resorcinol and passing through 7-hydroxy-8-methyl-coumarin as an intermediate stage. The same coumarin was also prepared by the reduction of umbelliferone-8-aldehyde and subsequent methylation.
Volume 14 Issue 4 October 1941 pp 1- Erratum
Volume 14 Issue 5 November 1941 pp 547-571
Volume 14 Issue 5 November 1941 pp 593-603
A brief survey of the existing literature on hydrogen bonds is made. The advantages of employing the Raman effect for investigations in this field are discussed. The results not only supplement those obtained from infra-red studies but they become more definite, particularly when such groups as the C=O, which yield sharp Raman lines, are employed.
Hydrogen bond formation between various esters as donor molecules and phenol, alcohols and chloroform as acceptor molecules has been studied and the results are presented in this paper. The changes in the C=O frequencies are classified. It is shown that there are large variations in the strengths of hydrogen bonds. The generalization that the strengths of hydrogen bonds depend on the anionoid power of the donor and the cationoid power of the acceptor atoms is made as a logical consequence of the mechanism of hydrogen bonds and is supported by the experimental results that are recorded.
Volume 14 Issue 6 December 1941 pp 643-647
A new flavonol, patuletin has been isolated from the petals of the flowers of
Volume 15 Issue 1 January 1942 pp 18-23
The constitution of montagnetol has been established as the erythrityl ester of orsellinic acid for the following reasons: (1) it gives the homofluorescein reaction slowly, (2) 5-hydroxy-4: 7-dimethyl coumarin could be obtained as a product of its condensation with ethylacetoacetate under the conditions of Pechmann’s reaction, (3) decomposition with hot dilute sulphuric acid or with hot baryta produces orcinol and erythritol, (4) concentrated sulphuric acid at 0° gives orsellinic acid and erythritol, (5) hot methyl alcoholic potash coverts it into methyl orsellinate and erythritol, and (6) by the action of diazomethane followed by methyl acloholic potash dimethyl ether of methyl orsellinate is obtained.
Volume 15 Issue 2 February 1942 pp 118-122
Flavylium salts containing γ- and α-pyrone rings have been prepared by condensing 7-hydroxy-3-methoxy-flavone-8-aldehyde and umbelliferone-8-aldehyde with hydroxy-aceto-phenones or their acetyl derivatives. They are found to have very feeble tinctorial properties and their fluorescence in concentrated sulphuric acid is not marked. The salts readily lose halogen and undergo conversion into colour bases.
Volume 15 Issue 3 March 1942 pp 148-153
A new flavonol glycoside has been isolated from the flower petals of
Volume 15 Issue 3 March 1942 pp 154-160
The Raman spectra of a few typical aldehydes and ketones and their mixtures with acceptor solvents such as phenol, methyl and ethyl alcohols and chloroform are recorded and the results are discussed. They support the general conclusion arrived at in Part I that large variations in hydrogen bond strengths exist and that they depend upon two factors (1) the anionoid power of the donor atom and (2) the cationoid power of the acceptor atom. The question of distinguishing between two types of hydrogen bonds, the hydrogen and hydroxyl bonds, as suggested by Bernal is discussed in the light of our results. It is shown that there is justification for division into two categories and a proposal is made to effect the classification as below: (1) True Hydrogen Bonds. (2) Hydrogen Bonds. In Class (1) both the cationoid (C=O) and anionoid (OH) centres are affected whereas in class (2) only the cationoid group indicates change.
The influences of constitutive factors on the capacity of the carbonyl compounds to form hydrogen bonds are explained as due to their effect on the strength of the C=O group. Similar explanation has already been given in Part I regarding the behaviour of the solvents containing cationoid atom (H atom) in hydrogen bond formation.
Volume 15 Issue 3 March 1942 pp 161-167
The work of Khuda
Volume 15 Issue 4 April 1942 pp 230-237
Previous work on the Raman spectrum of acetic acid and of its solutions is critically reviewed and certain conclusions criticised. The Raman spectra of the acid in the pure state as well as in aqueous solutions at different dilutions have been reinvestigated and the results described. A comprehensive interpretation of the observations is offered. It is shown that the breaking up of the ring dimers of the acid is brought about by the formation of hydrated molecules, and that the formation of fresh hydrogen bonds between the acid and water molecules is the cause of this breakdown of the ring type into the open dimers and finally into hydrates of the monomeric form of the acid molecules. These ideas are supported by a study of the Raman spectrum of a mixture of acetic acid with a good acceptor solvent, phenol. Changes similar to those obtained in aqueous solutions are produced in the C=O frequencies of the phenol mixture also.
Volume 15 Issue 4 April 1942 pp 238-243
Raman spectra of mixtures of acetic acid with a number of carbonyl compounds have been studied. It is shown that anionoid solvents affect the molecular aggregation of acetic acid, the effect being prominent with those having strong anionoid C =O groups such as coumarin and phenyl acetate. The breakdown of the ring dimers is not, however, complete in these cases. Definite evidence has been given for the presence of open dimers. There is justification for the view that water molecules serve also as anionoid molecules in effecting the breakdown of the ring dimers of acetic acid.
Volume 15 Issue 6 June 1942 pp 417-423
Pongamol, which is the second important crystalline component of the pongamia oil, has the molecular formula C18H14O4 and contains a methoxyl group. It has also a phenolic or enolic hydroxyl group. Demethylation with aluminium chloride yields nor-pongamol whereas treatment with hydriodic acid gives rise to a product which is probably isomeric but does not possess phenolic properties. Treatment with bromine produces a tetrabromo derivative which on boiling with acetone yields a tribromo compound. Oxidation with potassium permanganate or decomposition with alkali yields benzoic acid. From these properties and from colour reactions it is suggested that pongamol is a flavone derivative containing a hydroxyl, a methoxyl and an ethylene double bond.
Volume 15 Issue 6 June 1942 pp 424-428
The addition of cyanoacetamide to the double bond of 7-methoxy and 7-hydroxycoumarins is very slow and it is attributed to the influence of the substituents which act as electron sources. On hydrolysis, the products yield the corresponding cyanoacetic acid and acetic acid derivatives the latter of which could also be obtained by the reduction of methoxy and hydroxy coumarin-4-acetic acids using sodium amalgam. These compounds do not fluoresce in solution.
Volume 15 Issue 6 June 1942 pp 429-431
Alower melting sample of montagnetol has been isolated from
Volume 15 Issue 6 June 1942 pp 437-440
By the action of aluminium chloride on karanjin using nitrobenzene as solvent, smooth conversion into karanjonol could be effected. When benzene is used instead, besides demethylation a molecule of benzene adds on to yield α-phenyl-α: β-dihydro-karanjonol. Similar addition takes place in the case of toluene also. That the double-bond of the furan ring is involved in this reaction has been established by studying the behaviour of a few similar flavone compounds under the same conditions. It has been incidentally shown that a methyl ether group in the 3-position is readily affected in nitrobenzene solution whereas in the 7-position it is stable and the preparation of 7-methoxy-flavonol is easily carried out by demethylation of 3: 7-dimethoxy-flavone.
Volume 16 Issue 1 July 1942 pp 10-15
The important citrus fruits (oranges) of the Northern Circars belong to three species: (1)
Volume 16 Issue 1 July 1942 pp 23-28
The constitution of erythrin has been definitely established. The new important observations now made are as follows: (1) it is not a carboxylic acid; (2) it is optically active; (3) picroerythrin is identical with montagnetol; (4) trimethyl erythrin a compound in which all the phenolic hydroxyl groups are methylated is obtained by the action of diazomethane; (5) on hydrolysis with alcoholic potash the methyl ether yields the ester of dimethyl orsellinic acid and the ester of isoeverninic acid. Consequently, it is concluded that erythrin is the erythrityl ester of lecanoric acid. This is in agreement with the occurrence of lecanoric acid and montagnetol along with erythrin in the lichens.
Volume 16 Issue 1 July 1942 pp 29-35
Addition of cyanoacetamide to coumarins having substituents in the 3-position, such as the carbonyl, cyano and phenyl which are electronattracting, has been studied. Unlike alkyl groups and bromine atoms they do not in general inhibit addition. The following coumarins have been employed: (1) 3-acetyl-coumarin, (2) 3-benzoyl-coumarin, (3) 3-carbethoxy-coumarin, (4) coumarin-3-carboxylic acid, (5) 3-cyano-coumarin, and (6) 3-phenyl-coumarin. The speed of the reaction and the yield of the product depend upon (
Convenient methods for the preparation of 3-cyanocoumarin, coumarin-3-carboxylic acid and its piperidide have been investigated.
Volume 16 Issue 1 July 1942 pp 50-53
Raman spectra of mixtures of acetic acid with donor solvents not having C=O groups have been studied. The solvents chosen are dioxan and acetal. The results lend definite support to the mechanism described in previous papers (Parts III2 and IV1) of the progressive breakdown of the ring dimers of the acid into associates of the open dimers and eventually of the monomers with the solvent molecules. The extraordinary efficiency of water in bringing about the breakdown, is attributed to its dual capacity to act as both donor and acceptor.
Volume 16 Issue 1 July 1942 pp 68-82
From the data presented in the paper, the following points have been established: (1) Dihydro-umbelliferone and its derivatives, in which the pyrone double bond does not exist, do not give any fluorescence. (2) Similar to the carbonyl group cyano and phenyl groups enhance fluorescence emission markedly when present in the 3 position of umbelliferone. (3) No such effect is noticed when these groups occupy position 4. (4) A similar lack of influence is noticed in umbelliferone-3-acetic acid and its derivatives in which a methylene group breaks the conjugation. (5) Amongst monohydroxy coumarins, the presence of the hydroxy group in position 7 is most effective; in position 6, a feeble effect exists; in positions 5 and 8 no fluorescence is noticed. (6) Amongst dihydroxy-coumarins 6∶7, 5∶7, 8∶7, represent a decreasing series, the last giving no fluorescence. Derivatives of higher polyhydroxy-coumarins do not exhibit fluorescence. (7) Effect of methylation of the hydroxyl groups introduce marked changes in the capacity of the compounds to fluoresce and the colour of the fluorescence. 5-Methoxy-coumarin emits a feeble fluorescence whereas 8-methoxy compounds do not. (8) A few compounds exhibit fluorescence in the solid state. The above observations are explained from the effect of the structural features on the resonance of the molecule.
Volume 16 Issue 2 August 1942 pp 129-134
Employing a large number of natural and synthetic flavones, flavonols, flavanones and certain related compounds the scope of the following colour reactions has been examined: (1) reduction with magnesium and alcoholic hydrochloric acid, (2) reduction with sodium amalgam and alcohol and (3) Wilson’s boric acid test using boric and citric acid mixture in acetone solution. For the first two reactions the nature of the colour depends in general upon the number of hydroxyl or methoxyl groups in the molecule. In qualitative reactions it is not easily possible to effect minor distinctions between flavones, flavonols and flavanones. The boric acid test is very specific for 5-hydroxy- and 5-methoxyflavones and flavonols and
Volume 16 Issue 2 August 1942 pp 135-136
Volume 16 Issue 2 August 1942 pp 137-140
A complete examination of the lichen
Volume 16 Issue 2 August 1942 pp 141-145
With excess of aniline, gossypol forms tetraanilino-gossypol which decomposes on heating for a long time at 110° or for a short period at 180°, the products being aniline and dianilinogossypol. The two anilino compounds resemble closely except for the fact that the tetraanilino-compound contains more nitrogen and evolves aniline long before its final decomposition point is reached. Acetylation and methylation yield only gossypol derivatives, aniline being removed; acetyl and methyl derivatives of the anilino compounds could not be obtained.
Volume 16 Issue 2 August 1942 pp 146-150
The methods adopted by Adams
Volume 16 Issue 2 August 1942 pp 151-156
Angelicin and psoralen combine with benzene in the presence of aluminium chloride to form 8 or 6-α: β-diphenyl-ethylumbelliferone. Two molecules of benzene add on and the furan ring is opened out. That the coumarin ring is not involved and that the furan ring is the active centre are confirmed by the following observations: (1) Coumarin and 6-nitrocoumarin are unaffected; (2) umbelliferone and 4-methyl-umbelliferone methyl ether undergo simple demethylation; (3) coumarone undergoes polymerisation too vigorously to condense with benzene; (4) coumarilic acid undergoes addition with one molecule of benzene smoothly. Coumaric acid resembles coumarilic acid in regard to this reaction (addition) and differs from coumarin.
Volume 16 Issue 3 September 1942 pp 231-235
A simple procedure employing fish is described for determining the toxicity of chemical compounds. The ‘turning-point’ is taken as the criterion of toxic effect and the toxicity is expressed in terms of fish units that of rotenone being arbitrarily fixed as 1000. A few organic compounds belonging to the group pyronofurans have been studied.
Volume 16 Issue 4 October 1942 pp 244-249
The Raman spectra of methyl, ethyl,
Volume 16 Issue 4 October 1942 pp 264-269
Raman spectra of (1) propionic acid, (2) formic acid, (3) benzoic acid and (4) cinnamic acid have been studied using the pure acids in the liquid or molten condition and solutions in various solvents, benzene (non-associating), water, ether dioxan, acetal, etc. (associating). The first closely resembles acetic acid both of them indicating the existence of ring dimers, open dimers and monomers, the last two forms being present to a very small extent in the free state and in increasing quantities (in association with solvents) in solution in associating liquids. The state of the molecules in formic acid seems to be more complex due probably to the capacity of H of the C−H group to form hydrogen bonds. There are 2 broad C=O lines equally strong in the pure liquid at 1670 and 1715 cm.−1; the former diminishes and the latter increases in solutions with associating solvents. The narrowing of the band at 190 cm.−1 is another characteristic. It seems to be possible that in this acid no molecular type having unco-ordinated C=O exists. Benzoic and cinnamic acids form a different type. The molten acids and benzene solutions give only one C=O line corresponding to ring dimers and in fairly dilute solutions in ethers monomer-associates alone containing unco-ordinated C=O groups exist. Thus they do not give indications of the intermediate open type of dimers.
Volume 16 Issue 5 November 1942 pp 319-322
A crystalline compound melting at 197–8° and having the molecular formula C19H18O7 has been isolated from the roots of
Volume 16 Issue 5 November 1942 pp 323-327
The flower petals of
Volume 17 Issue 1 January 1943 pp 16-19
The initial stages in the synthesis of karanjin have been reinvestigated. A new synthesis of karanjol starting form ψ-resorcylic aldehyde is described. The aldehyde is condensed with bromoacetic ester (1 mol.) in the presence of sodium alcoholate and the product hydrolysed and eventually converted into 4-hydroxy-coumarone by well-known stages. The preparation of karanjic acid from karanjol is male best through the action of sodium methoxide and carbon dioxide. Further stages leading to the synthesis of karanjin have already been described.
Volume 17 Issue 1 January 1943 pp 20-25
By the oxidation of kanugin with potassium permanganate in acetone solution 4-o-methylresorcylic acid (I) and a neutral compound (II) containing methoxyl groups and having the formula C7H8O2 or C11H14O3 have been obtained. Hydrolysis with alcoholic alkali yielded an acid which seemed to be impure (I). The presence of a resorcinol unit in the molecule seemed to be thus established. Demethylation of kanugin gave rise to nor-kanugin. It had the properties of a flavonol (C16H12O7) and gave bright colours in alkaline buffer solutions. When its crystalline acetate was methylated a new methyl ether which was different from kanugin was produced. It was therefore concluded that by the action of hydriodic acid, besides demethylation some other changes were brought about.
Volume 17 Issue 1 January 1943 pp 26-31
A sample of the flower-petals of
Populnetin seems to be a new tetrahydroxy flavone and populnin is its monoglucoside.
Volume 17 Issue 2 February 1943 pp 55-57
The marked solubility of coumarin in aqueous mineral acids is attributed to the formation of complexes. That this takes place through hydrogen bonds is shown by a study of the Raman spectrum of these solutions wherein the carbonyl frequency is found to be considerably lowered, but still persists.
Volume 17 Issue 4 April 1943 pp 119-141
Volume 17 Issue 5 May 1943 pp 143-157
Volume 18 Issue 3 September 1943 pp 145-159
The latex of
Volume 18 Issue 4 October 1943 pp 201-203
A variety of
Volume 18 Issue 4 October 1943 pp 204-205
The new non-glycosidic substance obtained from the Indian cotton flowers has been shown to consist mostly of populnetin from a comparison of the methyl ethers. The characteristics of the methyl ether of populnetin are described.
Volume 18 Issue 4 October 1943 pp 206-209
A sample of Indian ergot of the Nilgiris has been studied in detail. It contains remarkably high percentage of total and water-soluble alkaloids. With respect to other components it is normal.
Volume 18 Issue 4 October 1943 pp 222-235
Based on the theory of Robinson
Volume 19 Issue 1 January 1944 pp 5-13
Claisen migrations of the allyl ether of 4∶7-dimethyl-5-hydroxy-coumarin gives rise to three isomeric compounds depending upon the conditions, (I) 6-allyl-5-hydroxy-4∶7-dimethyl coumarin (high yield), (II) the corresponding chroman (high yield), and (III) 8-allyl-5-hydroxy-4∶7-dimethyl coumarin (low yield). (II) has been shown to be a chroman by comparison with the corresponding methyl coumaran obtained by authentic methods from (I). The acetate of the above coumarin undergoes Fries reaction to give the 6-acetyl compound. Claisen migrations of the allyl ether of 7-hydroxy-5-methyl-coumarin yields only the 8-allyl-derivative. The difference in the behaviour of the derivatives of 5- and 7-hydroxy coumarins and the special conditions of the chroman and coumaran ring closure of
Volume 19 Issue 1 January 1944 pp 17-20
The Raman spectrum of salicylic acid has been studied for the first time in dioxan and benzene solutions. In the former monomolecular chelate structures associated with the solvent predominate; in the larter some chelate monomers exist, but the major portion consists of dimers whose structure is not quite clear. The spectrum of acetyl salicylic acid (aspirin) in dioxan seems to indicate that it has a chelate structure.
Volume 19 Issue 1 January 1944 pp 88-92
A convenient method of preparing 2∶4-dihydroxy-ω∶3∶6-trimethoxyacetophenone (I) directly from 2∶6-dibenzyloxy-1∶4-dimethoxybenzene is described. By the condensation of (I) with the sodium salt and anhydride of trimethylgallic acid, 7-hydroxy-3∶5∶8∶3′∶4′∶5′-hexamethoxyflavone (II) is obtained. Methylation of (II) yields a heptamethyl ether (III) identical with heptamethyl hibiscetin. Demethylation of (II) gives rise to a heptahydroxy flavone (IV) which is found to be identical with hibiscetin in all its properties and reactions. The constitution of hibiscetin is therefore confirmed by synthesis as 3∶5∶7∶8∶3′∶4′∶5′-heptahydroxy flavone.
Volume 19 Issue 3 March 1944 pp 141-145
Starting from γ-resorcylic aldehyde some typical 5-hydroxy and methoxy flavylium salts have been prepared and studied. They exhibit negligible fluorescence even in concentrated sulphuric acid. The structural factors that affect fluorescence in flavylium salts are discussed and comparison effected with coumarins.
Volume 20 Issue 1 July 1944 pp 1-14
Lichen depsides and depsidones are considered to arise from a common source (XIV) which originates from aldol condensation between a hexose and a biose and elimination of water. Oxidation and reduction lead to various modifications of this C8 unit and increase in the length of the sidechain arises from condensation with simple sugars and reduction. Depsides are formed by the combination of two of these units. β-Orcinol derivatives are obtained by nuclear methylation by means of formaldehyde and this reaction in general takes place prior to depside formation though the other possibility is not altogether excluded as far as the left half is concerned Depsidones come last in the evolution; they are based on depsides and require oxidation or dehydrogenation involving position 5 which is para to the activating hydroxyl. Nuclear oxidation without leading to depsidone formation also occurs. Either the 3-or the 5-position is involved and meta depsides result. Oxidation involving the left half is also possible and is represented by diploschistesic acid. The occurrence of orcinol and psoromic acid is attributed to decarboxylation taking place in the plant.
Volume 20 Issue 5 May 1945 pp 266-273
Past work on the chemical components of a number of plants of the family Asclepiadaceæ is reviewed. They are found to contain resinols though many of these were originally mistaken for sterols. With a view to test if this is an invariable rule another member,
Volume 20 Issue 5 May 1945 pp 274-278
Methyl ethers of 5∶6-dihydroxy-chalkones and flavanones have been prepared. 2∶5-Dihydroxy-6-methoxy acetophenone has been condensed with vanillin and 5∶6-dimethoxy-2-hydroxy-acetophenone with veratric aldehyde and anisaldehyde; the resulting chalkones have been converted into the flavanones. In the above reactions mixtures of chalkones and flavanones result.
Volume 20 Issue 5 May 1945 pp 279-291
Volume 21 Issue 1 January 1945 pp 8-18
A study of the wax and resin components of the stem bark of
An alcoholic extract of the wax-free stem bark yielded mineral matter consisting of citrates, chlorides and tartrates of sodium and potassium.
Volume 21 Issue 2 February 1945 pp 1- Erratum
Volume 21 Issue 3 March 1945 pp 130-133
The preparation of 3 ∶ 5 ∶ 6 ∶ 3′ ∶ 4′-pentahydroxy-flavone by Kostanecki's method and its properties are described. Its methyl ether and acetate have been prepared and characterised. These differ from patuletin and its derivatives.
Volume 21 Issue 4 April 1945 pp 147-154
The wax and resin components of the root bark of
Volume 21 Issue 4 April 1945 pp 155-161
The synthesis and properties of 6 ∶ 7 ∶ 3′ ∶ 4′-tetrahydroxy-flavonol and of its derivatives are described. ω ∶ 4-Dimethoxy-2-hydroxy-acetophenone is oxidised with persulphate in alkaline medium to yield ω ∶ 4-dimethoxy-2 ∶ 5-dihydroxy-acetophenone which is then condensed with veratric anhydride and sodium veratrate. The new flavonol and its methyl and acetyl derivatives differ from patuletin and its derivatives.
Volume 22 Issue 3 September 1945 pp 134-137
The phlobatannin components of kino gum and Butea gum have been purified and rendered free from water and ether-soluble impurities. By subsequent methylation and acetylation almost colourless methyl ethers and acetates have been obtained. They exhibit marked optical activity thus supporting the idea that the phlobatannins are probably hydroxyflavan derivatives. A comparison of the properties of the phlobatannins from the two sources and of their derivatives indicates that they are identical.
Volume 22 Issue 3 September 1945 pp 138-142
Mudarol, the chief resinol component of the root bark of
Volume 22 Issue 3 September 1945 pp 143-147
The latex of
Volume 22 Issue 3 September 1945 pp 157-162
8-Hydroxy-galangin, the lowest member of the gossypetin series of flavonols, has been prepared and its properties and reactions compared with the other members. Its important derivatives are described. The tetramethyl ether has been obtained by two methods, one of which is the direct condensation of gossypetol-tetramethyl ether, obtained by the fission of herbacetin pentamethyl ether, with benzoic anhydride and sodium benzoate.
Volume 22 Issue 4 October 1945 pp 215-224
The methylation of patuletin has been reinvestigated. It forms two methyl ethers, one with five methoxyl groups and the other with six. Decomposition of the latter with alcoholic alkali yields quercetagetol-tetra-methyl ether and veratric acid. Demethylation of patuletin produces quercetagetin. Patuletin is shown to be a mono-methyl ether of quercetagetin; from a study of its properties and reactions and from a comparison with related compounds, the methoxyl is tentatively considered to be in the 6-position.
Volume 22 Issue 5 November 1945 pp 289-292
The waxy matter isolated from the flowers of
Volume 22 Issue 5 November 1945 pp 297-303
Starting from ε-methoxy-resacetophenone and adopting the procedure described in Part 1, 6:7-dihydroxy flavonols with 0,1 and 3 hydroxyls in the side-phenyl nucleus have been prepared. The characteristic properties of the group with reference to the hydroxy-compounds and their partial and complete methyl ethers are described. An alternative method starting with hydroxy-quinol has also been investigated and the simplest member of the group prepared by this method also.
Volume 22 Issue 5 November 1945 pp 304-309
The ligroin extract of the flowers yielded waxy matter. One fraction of it consisted mainly of the esters of the resinols, α- and β-calotropeols and β-amyrin, with volatile as well as long chain fatty acids. There was also some sterol. The non-resinol aliphatic part contained mainly esters of wax acids and alcohols. The alcoholic extract of the wax-free flowers yielded only mineral matter—citrates, chlorides and tartrates of sodium and potassium.
The various parts of
Volume 22 Issue 6 December 1945 pp 383-388
Izalpinin (7-methyl ether of galangin) has been obtained by the demethylation of galangin di- and trimethyl ethers using both aluminium chloride and aluminium bromide. The synthetic sample has all the properties recorded for the naturally occurring substance. The condensation of ω:4:6-trimethoxy-phloroacetophenone with benzoic anhydride and sodium benzoate yields mainly 3:7-dimethyl ether of galangin.
Volume 23 Issue 1 January 1946 pp 23-36
A new and convenient synthesis of the flavonols of the quercetagetin series is described. ω: 4∶6-Trimethoxy-phloro-acetophenone has been prepared by two independent methods. By persulphate oxidation it is converted into the 2∶5-dihydroxy compound. Allan-Robinson condensation employing this ketone yields products containing a hydroxyl group in the 6-position. Subsequent demethylation and methylation yields the flavonols and their fully methylated ethers. Besides quercetagetin and tangeretin which occur in nature, 6-hydroxy galangin and 6-hydroxy myricetin which have not yet been discovered in natural products, have also been synthesised.
Volume 23 Issue 2 February 1946 pp 60-66
Kanugin C19H16O7 yields myristicic acid and
Volume 23 Issue 2 February 1946 pp 97-101
The synthesis of 3∶5∶ 6∶3′∶ 4′-pentahydroxy-flavone was already reported. The lower members of this group of 5∶ 6-hydroxy flavonols with one and no hydroxyl group in the side-phenyl nucleus have now been prepared by Kostanecki’s method. The characteristic properties are described.
Volume 23 Issue 3 March 1946 pp 134-139
6∶7∶8-Trihydroxy and 6∶7∶8∶4′-tetrahydroxyflavones and their derivatives (methyl ethers and acetates) have been prepared starting with 2-hydroxy-3∶4∶5-trimethoxyacetophenone and adopting the Baker-Venkataraman procedure. Their properties and reactions have been studied and compared with those of the isomeric compounds, baicalein and scutellarein.
Volume 23 Issue 3 March 1946 pp 140-146
The constitution of patuletin as 6-
Volume 23 Issue 3 March 1946 pp 147-151
The synthesis of 3-methoxy-7-hydroxy-3′∶4′-methylenedioxyflavone, kanugin and
Volume 23 Issue 4 April 1946 pp 192-208
Volume 23 Issue 4 April 1946 pp 209-212
The constitution of calycopterin as 5 ∶ 4′-dihydroxy-3 ∶ 6 ∶ 7 ∶ 8-tetramethoxy-flavone has been confirmed. Calycopterin diethyl ether has been shown to have ethoxyl groups in the 5 and 4′-positions, since on fission with alcoholic alkali, it yields
Volume 23 Issue 4 April 1946 pp 213-214
Volume 23 Issue 5 May 1946 pp 262-272
A simple and at the same time unambiguous method of synthesis of the 5∶6∶7-hydroxyflavones, baicalein and scutellarein and their derivatives is described. It starts from phloracetophenone which is partially methylated to the 4∶6-dimethyl ether. Oxidation of this ether with potassium persulphate yields the 2∶5-dihydroxy compound which on partial methylation produces 2-hydroxy-4∶5∶6-trimethoxyacetophenone. Using the benzoyl and anisoyl derivatives of this ketone and adopting the Baker-Venkataraman procedure, the trimethyl ether of baicalein and the tetramethyl ether of scutellarein have been prepared and from them the hydroxyflavones and their acetates.
Volume 23 Issue 5 May 1946 pp 273-277
Employing 2∶5-dihydroxy-4∶6-dimethoxyacetophenone and the Allan-Robinson method, the 5∶7-dimethyl ether of baicalein is obtained and from it by partial demethylation the 7-methyl ether. This is definitely different from oroxylin-A. The use of anisic anhydride in the above condensation yields two products, (1) 7∶4′-dimethyl ether of scutellarein and (2) 5∶7∶4′-trimethyl ether of 3-anisoyl-scutellarein. The former is different from the 6∶4′-dimethyl ether obtained from natural sources.
Volume 23 Issue 5 May 1946 pp 296-304
The methylation of the glucoside, cannabiscitrin and of the aglucone, cannabiscetin has now been effected by a more efficient method and the fission products examined. As the result cannabiscetin has been identified as myricetin and the identity has been confirmed by comparison of the flavonol and its derivatives with synthetic samples. It is noted that the reactions of flavonols having the pyrogallol side-phenyl nucleus exhibit many similarities with those given by flavonols having the 5∶7∶8-arrangement of hydroxyl groups. The condensation of hydroxy-fisetol-trimethyl ether with the anhydride and sodium salt of gallic acid yields pentamethyl-myricetin instead of the expected hexamethyl ether, partial demethylation having taken place in the 5 position during the course of the condendation.
Methylation of the glucoside, cannabiscitrin yields a pentamethyl ether which forms on hydrolysis pentamethyl cannabiscetin (myricetin). Alkali fission of this compound gives the same ketone as the hexamethyl ether. The acid part is identified as 4∶5-dimethyl gallic acid, thus locating the position of the sugar group definitely in the 3′ position of the flavonol. This result has been confirmed by ethylating the pentamethyl cannabiscetin and subjecting the ethyl ether to fission with alkali. Besides the ketone already mentioned, the acid decomposition product is found to be 3-ethyl-4∶5-dimethyl gallic acid by comparison with a synthetic sample. The synthesis of the ethyl-dimethyl gallic acid is described.
Volume 24 Issue 2 August 1946 pp 233-237
A method of complete synthesis of 5∶6∶7∶8-hydroxy flavonols is described. It starts from ω∶3∶6-trimethoxy-2∶4-dihydroxy-acetophenone which is subjected to partial methylation (of the 4-hydroxyl group) and subsequently to persulphate oxidation. The product, 2∶5-dihydroxy-ω∶3∶4∶6-tetramethoxy-acetophenone is condensed with the anhydride and sodium salt of anisic acid and also of benzoic acid. The resulting 6-hydroxy-flavones yield on further methylation the fully methylated ethers of calycopteretin and 6∶8-dihydroxy-galangin and on demethylation, the free hydroxy-flavonols.
Volume 24 Issue 2 August 1946 pp 238-242
A satisfactory procedure for the preparation of 2-hydroxy-ω∶3∶6-trimethoxy-4-benzyloxy-acetophenone is described. Oxidation of this to the 2∶5-dihydroxyketone (IV), its condensation with the anhydride and sodium salt of benzoic acid and subsequent demethylation yield 6∶8-dihydroxygalangin. This constitutes a simplified method for the synthesis of 5∶6∶7∶8-hydroxyflavonols and their methyl ethers.
Volume 24 Issue 2 August 1946 pp 243-253
Since there was an element of uncertainty in the methods employed in the past for the synthesis of 5∶7∶8-hydroxyflavone derivatives, an unambiguous method has now been worked out. The required ketone, 2-hydroxy-3∶4∶6-trimethoxyacetophenone has been prepared by the partial methylation of 2∶4-dihydroxy-3∶6-dimethoxyacetophenone which is obtained directly from 1∶4-dimethoxy-2∶6-dibenzyloxybenzene by the Hoesch reaction. It has been converted into 5∶7∶8-trimethoxyflavone (wogonin-dimethyl ether) and 5∶7∶8∶4′-tetramethoxyflavone by the Baker-Venkataraman procedure. Even the above dihydroxyketone could be used for this purpose fairly satisfactorily and it yields as an intermediate stage 5∶8-dimethoxy-7-hydroxyflavone. Demethylation with hydrodic acid even under mild conditions is not satisfactory. Nor-wogonin is best obtained by employing anhydrous aluminium chloride in benzene solution for this reaction.
Volume 24 Issue 4 October 1946 pp 344-348
Detailed chemical examination of the roots of
Volume 24 Issue 4 October 1946 pp 349-351
By the condensation of 2-hydroxy-ω: 3∶4∶5∶6-pentamethoxy-acetophenone with the anhydride and potassium salt of
Volume 24 Issue 4 October 1946 pp 352-356
The colouring matter of the flower petals of
Volume 24 Issue 4 October 1946 pp 357-364
Phyllanthin, the bitter principle of the leaves of
Volume 24 Issue 4 October 1946 pp 365-374
The roots of
Nallanin has the molecular formula C26H26O5, contains one methoxyl and two hydroxyls, one of which seems to be phenolic and the other alcoholic. On the other hand, Chandanin has the molecular formula C29H30O7 possesses three methoxyls and four phenolic hydroxyls; it seems to be rather extraordinary in its characteristics.
Volume 24 Issue 4 October 1946 pp 375-381
The analytical data indicate that gossypin is a monoglucoside. As a result of complete methylation and hydrolysis it yields an O-pentamethyl gossypetin. From a study of its decomposition with alcoholic potash whereby veratric acid is obtained and from a comparison of its properties with those of isomeric compounds, it is concluded that it has a free hydroxyl in the 8-position. Consequently gossypin should be 8-monoglucoside of gossypetin. The synthesis of O-pentamethyl gossypetin with a hydroxyl in the 3-position has been described.
Volume 24 Issue 5 November 1946 pp 456-464
Populnin is a monoglucoside of populnetin which is shown to be identical with kæmpferol. By the methylation and the subsequent hydrolysis of the glucoside a trimethyl ether of kæmpferol is obtained. Its colour reactions and properties indicate definitely that the free hydroxyl group is not in the 3− or 5-position. It has been compared with the isomeric 4′-hydroxy compound and found to be different. Thus the degradation product should have the hydroxyl in the 7-position. This is confirmed by ethylation and comparison of the ethyl ether and of its alkali degradation product (ketone) with synthetic samples.
Volume 24 Issue 5 November 1946 pp 465-472
A detailed examination of
The second component now named ‘robustenin’ melts at 188–89°, is neutral in nature and has the probable molecular formula C21H20O6. It contains two methoxyls.
Volume 25 Issue 1 January 1947 pp 22-24
The simpler methoxy flavones and some of the corresponding hydroxy compounds are markedly toxic to fish. This definitely establishes that the pyrone ring containing the atom grouping II is a toxophore.
Volume 25 Issue 1 January 1947 pp 43-50
Pajaneelin, the crystalline bitter principle of the bark of
Volume 25 Issue 4 April 1947 pp 333-336
The simpler coumarins are considerably less toxic as compared with the simpler flavones. This could be attributed to the lack of a side-phenyl nucleus in the former. 3-Phenyl and 4-phenyl umbelliferones and their methyl ethers are found to be highly toxic and compare favourably with 7-hydroxy and 7-methoxy-flavones. A large number of related coumarin derivatives have been studied for their toxicity towards fish.
Volume 25 Issue 4 April 1947 pp 337-340
A number of partial methyl ethers of hydroxy flavones and related compounds have been tested for toxicity to fish and the results are discussed with reference to structural characteristics. Calycopterin and its 4′-methyl ether are markedly toxic.
Volume 25 Issue 5 May 1947 pp 397-403
The constitution of gossypin as the 8-monoglucoside of gossypetin is confirmed by a detailed study of the pentamethoxy monohydroxy-flavone obtained by the complete methylation and subsequent hydrolysis of the glucoside. It is different from gossypetin-pentamethyl ether containing a free hydroxyl group in the 5-position but both give on oxidation the same quinone which is transformed into a quinol. Further its ethyl ether is shown to have the ethoxyl in the 8-position by unambiguous synthesis.
Volume 25 Issue 5 May 1947 pp 417-426
Nuclear oxidation leading to the preparation of 8-hydroxy-galangin and gossypetin has been carried out. 3∶7-dimethyl-ether of galangin and 3∶7∶ 3′∶4′-tetramethyl-ether of quercetin have been oxidised by means of potassium persulphate to the corresponding 5∶8-dihydroxy-compounds (quinols). Even the 5∶7-dihydroxy-compounds, 3-O-methyl-galangin and 3∶3′∶4′-O-trimethyl-quercetin could be oxidised to the corresponding 5∶7∶8-trihydroxy-derivatives in good yields. Subsequent methylation yields the fully methylated ethers of 8-hydroxy-galangin and gossypetin and demethylation the free hydroxy-flavonols. These experiments not only illustrate facile nuclear oxidation in the flavone series in support of the theory of biogenesis, but also constitute simple and elegant methods for the synthesis of 5∶7∶8-hydroxy-flavonols.
Volume 25 Issue 5 May 1947 pp 427-431
The nuclear oxidation of chrysin and tectochrysin has been successfully effected using potassium persulphate. The first yields norwogonin and the second the 7-methyl-ether now named isowogonin. The method of oxidative demethylation of the 5- and 8-positions has also been employed for the preparation of isowogonin from 5∶7∶8-trimethoxy-flavone.
Volume 25 Issue 5 May 1947 pp 432-437
The difficulty of the demethylation of synthetic primetin dimethyl ether into primetin has been solved by the use of anhydrous aluminium chloride in benzene medium. The possibility of the formation of primetin in the Primula through the intermediate stage of 5-hydroxy-flavone is suggested. This is supported by a new synthesis of primetin in which the nuclear oxidation of 5-hydroxy-flavone is effected by means of persulphate. 5-Hydroxy-flavone required for these experiments has been prepared by independent methods.
Volume 25 Issue 5 May 1947 pp 444-448
The synthesis of herbacetin and hibiscetin from kæmpferol and myricetin is described. As before, the partial methyl ethers of the latter have been subjected to nuclear oxidation with alkaline persulphate. The oxidation proceeds smoothly and gives rise to good yields of the products.
Volume 25 Issue 5 May 1947 pp 449-452
Extraction of the fruits of
Volume 26 Issue 1 July 1947 pp 13-17
Using the new discovery of facile nuclear oxidation in hydroxy-flavones, (1) wogonin and (2) its 5-methyl ether have been synthesised. Starting with 7-O-benzyl-chrysin, oxidation followed by partial methylation and debenzylation yields (1) and by complete methylation and debenzylation hields (2).
Volume 26 Issue 1 July 1947 pp 18-21
It is shown that 5:6:7:8-hydroxy-flavonols (Calycopterein series) can be made from 5:6:7-hydroxy-flavonols (quercetagetin series) by the nuclear oxidation of the 8-position. Quercetagetin and nor-tangeretin have thus been converted into 6:8-dihydroxy-quercetin and calycopteretin in good yields.
Volume 26 Issue 1 July 1947 pp 46-51
Jack tree latex has the same composition as the fruit gum. Besides proteins and mineral substances, the two contain a high percentage of waxy matter. The less soluble portion (small amount) of the wax yields on saponification a non-steroid substance melting at 96-7° and having probable composition of C30H58O2. The more soluble major fraction yields artostenone on saponification. Experiments indicate definitely that this ketone is not occurring free and that it is formed as a result of the saponification. Though artostenone does not have the capacity of forming enolesters, α-artostenone yields an enol-benzoate readily. Further α-artostenone and its enol-ester undergo conversion into artostenone under the conditions of saponification. Hence the conclusion is drawn that in the plant it is α-artostenone that occurs in the form of enol-wax-esters.
Volume 26 Issue 1 July 1947 pp 72-76
By partial ethylation tambuletin forms a definite triethyl-ether giving reactions for a free hydroxyl group in the 5-position. It undergoes oxidative demethylation thus confirming the location of the methyl-ether group in the 8-position. Complete ethylation yields O-tetraethyl-tambuletin which is found to be identical with 3∶5∶7∶4′-tetraethoxy-8-methoxy-flavone, synthesised from kaempferol using the method of nuclear oxidation.
Volume 26 Issue 3 September 1947 pp 178-181
Volume 26 Issue 3 September 1947 pp 182-188
Nuclear oxidation of baicalein and scutellarein takes place readily in the 8-position, the partial methyl ethers being employed. Further methylation yields fully methylated ethers of the nobiletin series and demethylation the corresponding nor-compounds. For purposes of comparison these substances have also been prepared from 2∶5-dihydroxy-3∶4∶6-trimethoxy acetophenone by the Allan-Robinson method. The characteristic properties and reactions of these compounds are described.
Volume 26 Issue 3 September 1947 pp 189-196
The synthesis of some flavonols with only one hydroxy group in the 5-position of the benzo-pyrone part has been effected starting from the monomethyl ether of 2-acetyl resorcinol and adopting the chalkone method of Kostanecki. The mono-methyl ether of 2-acetyl resorcinol is condensed with benzaldehyde, anisaldehyde and veratric aldehyde and the resulting chalkones converted into flavanones and flavonols. Thus 3∶5-dihydroxy-, 3∶5∶4′-trihydroxy-, and 3∶5∶3′∶4′-tetrahydroxy flavones, their methyl ethers and acetates have been prepared and their properties studied. These flavonols differ markedly from the isomeric compounds containing only one hydroxyl group in the 7-position of the benzopyrone part.
Volume 26 Issue 3 September 1947 pp 203-204
α-Artostenone has been prepared directly from Jack fruit gum by saponification using sodium methoxide in cold methyl alcoholic solution. In preliminary tests α-artostenone enol-benzoate was found to yield α-artostenone under these conditions. Thus the conclusion that α-artostenone occurs in the plant in the form of enol-wax-esters is confirmed.
Volume 26 Issue 3 September 1947 pp 214-220
According to Bose and Bose2 tambulin should be 3∶8∶4′-trimethyl-ether of herbacetin. A compound of this constitution has now been synthesised from 3∶4′-dimethyl-ether of kaempferol. Its properties differ markedly from those of tambulin. The constitution of the latter should therefore be considered as still unsettled. The nature of the synthetic substance has been confirmed by preparing its diethyl-ether and proving its identity with 3∶8∶4′-trimethyl-5∶7-diethyl-ether of herbacetin prepared by an independent method.
Volume 26 Issue 4 October 1947 pp 234-236
The synthesis of tambuletin has been effected. Kaempferol is first benzylated to the tribenzyl-ether which is subjected to oxidation with alkaline persulphate, partial methylation and debenzylation in succession.
Volume 26 Issue 4 October 1947 pp 236-236 Erratum
Volume 26 Issue 5 November 1947 pp 288-291
The 6-methyl ether of euxanthone has been oxidised to 6-methoxy-1∶4-dihydroxy-xanthone by means of alkaline persulphate. By demethylation with hydriodic acid 1∶4∶6-trihydroxy-xanthone has been obtained. This compound and its derivatives differ from those obtained by Nierenstein by the oxidation of euxanthone itself with chromic acid and subsequent reduction.
Volume 26 Issue 5 November 1947 pp 292-295
Gossypin has been ethylated and hydrolysed. The resulting pentaethyl ether of gossypetin is further methylated and the product converted into tetra-ethyl tambuletin by alkali fission and condensation of the ketonic product with the anhydride and sodium salt of
Volume 26 Issue 5 November 1947 pp 296-298
Based on the evidences recorded in the past the constitution of tambulin is considered to be 7∶8∶4′-O-trimethyl-herbacetin. A substance of this constitution is synthesised by the partial demethylation of herbacetin-pentamethyl ether and is found to agree very closely with tambulin in properties. Hence its constitution is considered to have now been established.
Volume 26 Issue 5 November 1947 pp 299-311
Resorcinol condenses with succinic anhydride forming resorcinolsuccinein as the main product and tetrahydroxy-dibenzoyl-ethane as a very minor by-product. Orcinol also gives a good yield of orcinol-succinein. These could be used conveniently for the preparation of halogen and mercury substituted derivatives. Resorcinol gives only a poor yield of the malein, the major condensation product with maleic anhydride being the diketone, tetrahydroxy-dibenzoyl-ethylene. Phenol does not give any isolable quantity of succinein or malein and only the corresponding diketones could be isolated by condensation with succinic anhydride and maleic anhydride. A number of derivatives of the diketones are described.
Volume 27 Issue 1 January 1948 pp 33-36
The simpler chromones having no side phenyl ring have poor toxic properties and resemble the simpler coumarins. Hydroxy isoflavones are more toxic than the corresponding flavones and the methoxy derivatives less toxic. In this there is resemblance to the hydroxy- and methoxy-phenyl coumarins. Among allyl-derivatives of chromones, flavones and isoflavones, ethers have high toxicity.
Volume 27 Issue 1 January 1948 pp 37-43
The possibility of orthor nuclear oxidation in the flavone series has been tested using 7-hydroxy-flavone and 3-methoxy-7-hydroxyl-flavone. By means of alkaline persulphate 7: 8-dihydroxy-flavone (10% yield) and 3-methoxy-7: 8-dihydroxy-flavone (20% yield) could be obtained. This seems to offer an easier method of preparing the flavonol, 3: 7: 8-trihydroxy flavone. The intermediate stage of the sulphate could be isolated pure from 7-hydroxyflavone.
Volume 27 Issue 2 March 1948 pp 85-90
It is shown that the nuclear oxidation of hydroxy-chalkones can be successfully effected thereby introducing a fresh hydroxyl in the 5-position which corresponds to the 6-position in flavanones and flavones. 2-Hydroxy-4-methoxy-chalkone and 2-hydroxy-4∶6-dimethoxy-chalkone have thus been oxidised to the 2∶5-dihydroxy compounds. In the first case the product is shown to be 2∶5-dihydroxy-4-methoxy-chalkone by complete methylation and identification of the derivative as 2∶4∶5-trimethoxy-chalkone. In the second case it is proved to be 2∶5-dihydroxy-4∶6-dimethoxy-chalkone by partial methylation and conversion into 5∶6∶7-trimethoxy-flavanone.
Volume 27 Issue 2 March 1948 pp 91-103
The constitution suggested by Bose for gardenin (5-hydroxy-3∶6∶8∶3′∶4′∶5′-hexamethoxy-flavone) has been confirmed in the following manner.
Preparation of nor-gardenin and gardenin methyl ether and comparison with hibiscetin and 6-hydroxy-myricetin and their methyl ethers. There was no agreement.
Oxidative demethylation of gardenin and its methyl ether. This proved that groups exist in the 5 and 8 positions.
Alkali fission of methyl gardenin and study of the ketonic product. It condensed with the anhydride and sodium salt of trimethyl gallic acid to reform gardenin. Its oxidation with nitric acid and subsequent transformations showed that it has a methoxyl in the 5-position corresponding to the 6-position in gardenin.
The tetramethoxy flavone obtained from the fission ketone and benzoic anhydride and sodium benzoate was not identical with 5∶6∶7∶8-tetramethoxy-flavone, but was identical with 3∶5∶6∶8-tetramethoxy-flavone synthetically obtained by the method of nuclear oxidation.
Gardenin could be directly obtained by the partial methylation of nor-gardenin or gardeninol and by the Allan-Robinson condensation using the fission ketone and trimethyl gallic acid.
Volume 27 Issue 2 March 1948 pp 104-110
Analysis and study of acid hydrolysis show that hibiscitrin is a monoglucoside of hibiscetin. It undergoes complete methylation with dimethyl sulphate and anhydrous potassium carbonate in anhydrous acetone medium; on hydrolysing the methyl ether a O-hexamethyl hibiscetin is obtained which yields trimethyl gallic acid on fission with alkali. From this reaction and from other characteristic properties of the above partial methyl ether it is concluded that the free hydroxyl is in the 3-position and that hibiscitrin is a 3-glucoside.
Volume 27 Issue 2 March 1948 pp 111-120
A more detailed study of scandenin is made and its important properties compared with those of lonchocarpic and robustic acids. The three non-rotenoids show marked resemblance. They do not give the Durham test, and are definitely acids owing this property not to carboxyl groups but to specially active hydroxyl groups. They are quite stable to aqueous and alcoholic alkali. The fully methylated ethers have three methoxy groups in all the three cases and these ethers undergo decomposition readily in alcoholic alkali in the presence of zinc, the main products being neutral in nature. The three compounds do not give chemical tests for the presence of carbonyl groups, exhibit definite toxicity to fish and have very similar ultra-violet absorption spectra. The toxicity and the spectra indicate the presence of carbonyl groups in conjugation with ethylenic bonds.
Oxidation with alkaline hydrogen peroxide yields
Volume 27 Issue 2 March 1948 pp 128-131
The toxic properties of a number of simple hydroxy and methoxy flavanones and chalkones have been studied using fresh-water fish. The flavanones resemble the flavones in a general way. However the methyl ethers of the flavanones appear to be less toxic than the corresponding flavone derivatives, whereas with the hydroxy compounds the reverse seems to be the case.
With the chalkones the toxic symptoms set in more slowly but they are more persistent. The methoxy chalkones are less toxic than the isomeric flavanones whereas when a number of hydroxyl groups are present the reverse is the case. As soon as all the hydroxyl groups in chalkones are methylated the toxicity increases considerably.
Volume 27 Issue 3 March 1948 pp 209-216
The constitution of hibiscitrin proposed in Part I as the 3-glucoside of hibiscetin is confirmed here by synthetic experiments. The O-hexamethyl hibiscetin (A) has been ethylated to (B). Using the method of nuclear oxidation a hexamethyl hibiscetin with a free hydroxyl in position 5 is now prepared and shown to be different from (A). Ethyl ethers of the isomeric 8- and 3-hydroxy compounds are also prepared. The former is different from (B) whereas the latter is identical with it.
Though alkali fission of (A) does not yield the ketonic part, the ethyl ether (B) can be satisfactorily employed for this fission. The ketonic product is found to be identical with ω-ethoxy-2-hydroxy-3: 4: 6-trimethoxy-acetophenone obtained synthetically, thus confirming again the above constitution of (B) and of hibiscitrin.
Volume 27 Issue 3 March 1948 pp 217-222
Nobiletin has been synthesised by adopting the method of nuclear oxidation of the flavone skeleton. For this purpose 6-hydroxyluteolin has been prepared for the first time and subjected to partial methylation, oxidation and final methylation successively whereby nobiletin is obtained. Demethylation of this yields nornobiletin having all the propertics described in the literature. Nobiletin has also been prepared independently from 2: 5-dihydroxy-3: 4: 6-trimethoxy-acetophenone by condensation with sodium veratrate and veratric anhydride and subsequent methylation.
Volume 27 Issue 3 March 1948 pp 223-239
A marked difference in the behaviour of naringin and of butrin towards hydrolysing agents has been noticed previously. Thus naringin yields the flavanone, naringenin, while butrin yields a mixture of the flavanone, butin, and the chalkone, butein. Similar difference in behaviour is also exhibited by the flavanones, naringenin and butin, when treated with mineral acids or alkalis.
Methylation has now been conducted of the glycosides, naringin and butrin and their aglucones naringenin and butin using varying molar proportions of dimethyl sulphate in the presence of anhydrous potassium carbonate and in acetone solution. From the study of the products and also of a number of simpler flavanone derivatives it is clear that the presence of a free 5-hydroxyl gives stability to the pyranone ring. This stability is not found when the 5-hydroxyl is non-existent as in butrin and butin or gets methylated as in some of the methyl ethers of naringin and naringenin and other flavanones; the products are chalkones in these cases.
The special influence of the 5-hydroxyl group in stabilising flavanone structure is attributed to the existence of chelation between this hydroxyl and the carbonyl group of the pyranone ring. The mechanism of the chalkone-flavanone conversion is discussed.
Volume 27 Issue 4 April 1948 pp 245-257
Using typical examples, some of which are new, oxidative demethylation of methoxy benzenes, ketones, chalkones and flavones with nitric acid is discussed. The flavones without exception undergo simple conversion into para quinones. The others fall into two categories: (
Under favourable conditions hydroxy quinones can be methylated by means of dimethyl sulphate and potassium carbonate to the corresponding methyl ethers,
Volume 27 Issue 4 April 1948 pp 258-259
Gossypitrin is fully methylated by means of dimethyl sulphate and potassium carbonate in acetone medium. The pentamethyl gossypetin obtained by hydrolysis has been directly compared with a synthetic sample and mixed melting point taken. Its ethyl ether has also been made.
Volume 27 Issue 4 April 1948 pp 260-264
In an earlier paper it was remarked that the colour reactions of norgardenin were rather extraordinary. Other flavonols belonging to the 5∶6∶8-hydroxy series and their methyl ethers have now been prepared using the fission ketone from methyl gardenin, and their properties studied. Their colour reactions resemble those of nor-gardenin and methyl gardenin closely. In general the hydroxy-flavonols of this series exhibit reactions with alkaline buffer solutions differing markedly from their isomers belonging to the 5∶7∶8- or 5∶6∶7- series thus emphasising the importance of the 7-hydroxyl for this purpose.
Volume 27 Issue 5 May 1948 pp 1- Erratum
Volume 27 Issue 5 May 1948 pp 375-390
Pedicin is considered to be a
Volume 27 Issue 6 June 1948 pp 409-410
Volume 28 Issue 1 July 1948 pp 1- Erratum
Volume 28 Issue 1 July 1948 pp 1-18
The results contained in the recent publications from this laboratory on the subject of nuclear oxidation in the flavones and related compounds are summed up. Originally the main interest was in the theory of biogenesis of anthoxanthins; the bearing of the results on the evolution of the various types of flavones and flavonols is therefore discussed in detail. This study has led to the development of considerably simplified methods of synthesis of all the naturally occurring substances with three and four hydroxyl groups in ring A and of the special though simpler compounds like primetin. The application of this oxidation method along with ethylation for the establishment of the structure of partial methyl ethers as well as glycosides is illustrated by a number of typical examples. Special mention is made of the interesting and novel cases like gardenin and pedicin.
Volume 28 Issue 1 July 1948 pp 19-25
Volume 28 Issue 2 August 1948 pp 31-39
Synthetic confirmation for the constitution of quercetagitrin is provided. The pentamethyl-quercetagetin obtained by the complete methylation and hydrolysis of the glucoside is finally ethylated and the product shown to be identical with a synthetic sample of 7-ethoxy-3∶5∶6∶3′∶4′-pentamethoxy flavone (V) made from 2-hydroxy-4-ethoxy-ω: 6-dimethoxy-acetophenone (VI) using oxidation with persulphate, Allan-Robinson condensation and final methylation as stages. The ketone (VI) is conveniently made by the alkali fission of
Volume 28 Issue 3 September 1948 pp 94-95
Volume 28 Issue 3 September 1948 pp 96-97
Resokæmpferol, its tri-acetate and tri-methyl ether are prepared and described.
Volume 28 Issue 3 September 1948 pp 98-102
In continuation of Part VIII, members of the 3-methoxy-7-hydroxyflavone series with one, two and three methoxyl groups in the side phenyl nucleus are subjected to ortho-oxidation with alkaline persulphate; the yield of the corresponding 7∶8-hydroxy compounds is 10 to 15%. On the other hand, attempts at ortho-oxidation by this method in the side phenyl nucleus have failed just as in several cases of simpler benzene derivatives. It is suggested that ortho-oxidation in nature should be considered to take place in multiple stages and this has been verified using a convenient example in the flavone series. 3-Methoxy-7-hydroxy-flavone undergoes change into the corresponding 8-aldehyde by the action of hexamine and this is converted into 3-methoxy-7∶8-dihydroxy flavone by means of alkaline hydrogen peroxide, the yields being very good.
Volume 28 Issue 3 September 1948 pp 103-110
An essential point which has not been established in a simple manner by the previous study of pedicinin and its synthesis relates to the position of the methoxyl group. This has now been settled in an unambiguous manner by the reduction of pedicinin with stannous chloride to dihydropedicinin and its ethylation. The product is found to be identical with 4-methoxy-2∶3∶5∶6-tetraethoxy chalkone obtained synthetically starting from 2∶6 dimethoxy quinol. This chalkone undergoes oxidative de-ethylation with nitric acid yielding ethyl pedicinin and eventually pedicinin.
The toxic properties of dimethyl pedicinin (2∶4∶5-trimethoxy-quino chalkone) have been studied using fish.
Volume 28 Issue 4 October 1948 pp 189-197
The experiments described in this paper show that a pure sample of oroxylin-A melts at 219–20° (acetate, 139–40°), that the substance melting at 231–32° is a mixture of it with chrysin and that this mixture could be separated by fractionation of the acetates. The constitution of oroxylin-A as the 6-methyl ether of baicalein is confirmed by ethylating it to the diethyl ether and showing that the product is identical with a synthetic sample of 6-methoxy-5 ∶ 7-diethoxy flavone. The details of the synthesis are given.
Volume 28 Issue 4 October 1948 pp 198-209
Though despedicellin and dihydropedicinin are prepared from chalkones and were earlier given the chalkone constitution, their properties indicate that they are flavanones. This constitution is also in accordance with the recent discovery of the new effect of hydrogen bonds on the stability of flavanones. It is confirmed by the following experiments. (1) The two compounds undergo partial methylation with diazomethane yielding 5-hydroxy-6: 7∶8-trimethoxy-flavanone which forms with nitric acid 6∶7-dimethoxy-quinoflavanone identical with the sample obtained from 5∶6∶7∶8-tetramethoxy flavanone. (2) Dihydropedicinin undergoes oxidation with
Volume 28 Issue 4 October 1948 pp 210-215
The most important example of ortho-oxidation from the point of view of the biogenesis of the anthoxanthins is the conversion of quercetin into myricetin.
Volume 28 Issue 6 December 1948 pp 574-578
Volume 28 Issue 6 December 1948 pp 579-581
The observation of Bose and Nath regarding the fission of gardenin with alcoholic potash is confirmed. The formation of ω-methoxy-3∶6-dihydroxy-2∶5-quino-acetophenone (II) in this reaction constitutes an example of oxidative demethylation by means of alcoholic potash. The same compound can be obtained from methyl gardenin through the stages (III) and (IV). Analogous partial methyl ethers of flavones with a free 5-hydroxyl are resistant to this treatment.
Volume 29 Issue 1 January 1949 pp 1-8
Phloroacetophenone-2 ∶ 4-dibenzyl ether is prepared; it does not undergo persulphate oxidation satisfactorily. Monobenzylation of phloroacetophenone yields the 4-benzyl ether readily; it is partially methylated to the 2-methyl-4-benzyl ether. Starting with this compound, persulphate oxidation, Allan-Robinson condensation using benzoic anhydride and sodium benzoate and methylation produce 5 ∶ 6-dimethoxy-7-benzyloxyflavone Hydrobromic acid causes besides debenzylation, demethylation in the 5-position. The final product is the 6-methyl ether of baicalein which is identical with oroxylin-A isolated from the root and stem barks of
Volume 29 Issue 1 January 1949 pp 9-15
The following three partial methyl ethers of flavonols which are derivatives of naturally occurring monoglucosides having only one free hydroxyl group have been conveniently synthesised by using the method of partial benzylation: (1) 3 ∶ 5 ∶ 4′-O-trimethyl-kæmpferol derived from populnin and related glycosides, (2) 3 ∶ 5 ∶ 3′ ∶ 4′-O-tetramethyl quercetin derived from quercimeritrin and (3) 3 ∶ 5 ∶ 7 ∶ 3′ ∶ 4′-O-pentamethyl gossypetin derived from gossypin.
Volume 29 Issue 2 February 1949 pp 72-79
Apigenin does not undergo persulphate oxidation satisfactorily. But acacetin, its monomethyl ether and analogous higher members do so. By the methylation of the products (quinols) the fully methylated ethers of isoscutellarein, 8-hydroxyluteolin and 8-hydroxytricetin could be readily obtained. Demethylation of the quinols or their methyl ethers with aluminium chloride is not successful. Boiling with hydriodic acid produces isomeric change yielding conveniently scutellarein and the higher members. 6-Hydroxy-tricetin and its derivatives are newly described.
Volume 29 Issue 2 February 1949 pp 80-90
The use of ethylation in the study of naturally occurring glycosides and partial methyl ethers of hydroxy flavones is discussed. This procedure renders the work simpler and more definite. Starting from ω-ethoxy res-and phloracetophenones, the preparation of mixed ethyl methyl ethers of the flavonols, fisetin, kæmpferol, and quercetin, with an ethoxyl in the 3-position and methoxyls in the other positions, is described and it is shown that these compounds are useful in the study of the 3-glycosides of these flavonols. The case of rutin has been used as a typical example.
As an illustration of the synthesis of fully ethylated compounds fisetin tetraethyl ether is made and as an example for the use of ethylation in the study of both 7-glycosides and 7-methyl ethers, O-3∶3′∶4′-triethyl-7-methyl-fisetin is synthesised.
The use of ethylation for establishing interrelationship between glycosides and partial methyl ethers of hydroxy flavones is illustrated with the case of quercimeritrin and rhamnetin. Quercimeritrin has been ethylated with diethyl sulphate and the ethylated glucoside hydrolysed and methylated. The product is a mixed ether of quercetin and is shown to be identical with O-tetraethyl rhamnetin.
Volume 29 Issue 3 March 1949 pp 168-170
The trimethyl ether of fisetin with a free hydroxyl group in 4′-position yields the 5′-aldehyde readily by the action of hexamine. Subsequent oxidation with hydrogen peroxide gives rise to good yields of robinetin trimethyl ether. Its methylenation leads to the synthesis of kanugin and demethylation to the formation of robinetin. This constitutes another example of the two stage ortho-oxidation of the side phenyl nucleus of the flavonols.
Volume 29 Issue 4 April 1949 pp 221-226
The two stage process of ortho-oxidation is applied to partial methyl ethers of gossypetin in order to introduce a new hydroxyl in the 6 position. The pentamethyl ether with a free hydroxyl in the 7- position does not react with hexamine. On the other hand, its isomer with a free 5-hydroxyl yields a mixture of products, one of which is the 6-aldehyde which could be oxidised by means of hydrogen peroxide. A more satisfactory procedure is to use the tetramethyl ether having the 5 and 8 hydroxyls free. It yields only the 6-aldehyde and subsequent oxidation with hydrogen peroxide leads to the formation of 5∶6∶8-trihydroxy compound. The products are useful partial methyl ethers and yield 6∶8-dihydroxy-quercetin on demethylation and its heptamethyl ether on methylation.
Volume 29 Issue 4 April 1949 pp 265-268
Partial demethylation of 2-hydroxy-4 ∶ 6-dimethoxy chalkone with aluminium chloride yields 2 ∶ 4-dihydroxy-6-methoxychalkone which could be cyclised to 5-methoxy-7-hydroxy-flavanone. The use of hydrobromic acid for the demethylation produces directly 5-hydroxy-7-methoxy flavanone due to initial ring closure and subsequent demethylation in the 5-position of the flavanone. When this reagent acts on 2-hydroxy-4 ∶ 6 ∶ 4′-trimethoxy chalkone sakuranetin, the naturally occurring monomethyl ether of naringenin is produced.
Volume 29 Issue 6 June 1949 pp 394-403
A method of distinguishing between a flavone and a flavonol and characterising the latter is described. It consists in subjecting the ketonic fission product of the fully methylated anthoxanthin, representing the condensed benzene nucleus to the action of 40% aqueous hydrobromic acid, ω-Methoxy-ketones derived from flavonols yield coumaranones which could be converted into benzylidene derivatives. Simpler examples and more difficult cases such as gossypetol-tetramethyl-ether and calycopteretol pentamethyl-ether have been used for the investigation. The nature of the products has been proved by independent synthesis. The ketone obtained by the fission of methyl gardenin undergoes this reaction and hence supports the constitution of gardenin as a flavonol. Ortho-hydroxy-ketones which are unsubstituted in the ω-position do not yield any crystallisable product in this reaction.
Volume 29 Issue 6 June 1949 pp 404-412
The method of demethylation using aluminium chloride in benzene medium is shown to be applicable to polymethoxy flavanones. 5∶7∶4′-, 5∶7∶8- and 5∶6∶7-trimethoxy flavanones yield the corresponding trihydroxy compounds. Similarly carthamidin and isocarthamidin are obtained from their tetramethyl ethers whose synthesis is described. This work provides synthetic confirmation of the constitution of these tetrahydroxy flavanones proposed by Kuroda. That no isomeric change takes place in the preparation of carthamidin is established by its methylation to its tetramethyl ether.
Volume 30 Issue 1 July 1949 pp 12-14
A new synthesis of nobilein has been achieved employing the two stage process of ortho-oxidation. 5∶8-Dihydroxy-7∶3′∶4′-trimethoxy flavone (III) is condensed with hexamine to yield the 6-aldehyde (IV) which undergoes smooth oxidation with hydrogen peroxide to 7∶3′∶4′-trimethyl ether (V) of nornobiletin. Final methylation of (V) produces nobiletin (VI).
Volume 30 Issue 1 July 1949 pp 15-22
Volume 30 Issue 1 July 1949 pp 30-34
A characteristic blue or green colour reaction with concentrated nitric acid is given by the fully alkylated ethers of resorcinol and phloroglucinol and by a number of carbonyl derivatives of them. n the case of these carbonyl compounds one orthohydroxyl could be free. Certain flavanone derivatives of phloroglucinol also give this test whereas chalkones, flavones, diketons and coumaranones do not. It is useful for the differentiation and characterisation of closely related and isomeric compounds belonging to the above categories.
Volume 30 Issue 2 August 1949 pp 62-66
Two lichens are found on the sandal trees of Coorg which do not suffer adverse effects on this account.
Volume 30 Issue 2 August 1949 pp 67-73
A yellow lichen accompanying
Volume 30 Issue 2 August 1949 pp 78-81
Volume 30 Issue 3 September 1949 pp 107-113
Kellin (I) has been synthesised starting from 2-methyl-5 ∶ 7-dihydroxychromone (VII). The stages are as follows: (1) treatment with bromacetic ester (VIII); (2) oxidation with alkaline persulphate in which the ester group sets hydrolysed (IX); (3) partial methylation with 2 moles of dimethyl sulphate (X); (4) condensation with hexamine to introduce an aldehyde group in the 6-position (XI); (5) complete methylation (XII); (6) gentle alkali hydrolysis to aldehydo-acid (XIII); and (7) final boiling with acetic anhydride and sodium acetate. Kellin-quinone and nor-kellin have been prepared as convenient derivatives.
Volume 30 Issue 3 September 1949 pp 114-119
Employing the two stage process of ortho-oxidation eugenol is converted into 5-hydroxy eugenol. Methylation of this yield elemicin and methylenation myristicin. This constitutes the most convenient synthesis of these naturally occurring compounds and is highly significant from the point of view of biogenesis.
Volume 30 Issue 3 September 1949 pp 120-127
The structure of 6-methoxy-4 ∶ 5 ∶ 7-trihydroxy-benzal-coumaranone was suggested by Salooja
Volume 30 Issue 4 October 1949 pp 151-162
Iodine, in the presence of hot alcoholic sodium acetate, is shown to be a convenient reagent for the conversion of hydroxy flavanones into flavones. Naringenin, its 4′ and 4′: 7-dimethyl ethers, hesperetin and its dimethyl ether are thus oxidised smoothly into apigenin and its ethers and diosmetin respectively. The method is also suitable for glycosides; examples chosen are naringin, its monomethyl ether and hesperidin. The constitution of apiin is discussed and confirmed by correlation with that of naringin.
The method works smoothly in all cases where a free hydroxyl is present in the 5-position. In its absence a mixture is formed; by working in the cold the flavones can be obtained, whereas in the hot benzalcoumaranones could be isolated. In such cases the suitability of the phosphorus pentachloride method has been tested using 7-methoxy flavanone.
The reaction is considered to involve (1) iodination of the 3-position and (2) elimination of hydriodic acid and these are brought about smoothly with the help of the active and unstable acetate ions. If the second stage involves iodinated flavanone, flavone is obtained; on the other hand if the corresponding iodinated chalkone is present, benzal-coumaranone results.
Volume 30 Issue 4 October 1949 pp 163-172
Two isomers of methyl pedicinin are synthesised and studied: (1) 4: 7-dihydroxy-5: 6-dimethoxy-benzal-coumaranone and (2) 5: 6-dimethoxy-4: 7-quino-benzyl-coumaranone. The first is made from 2-hydroxy-3: 4: 5: 6-tetramethoxy-chalkone by conversion into the corresponding benzal-coumaranone, oxidative demethylation to 4: 7-quinone and reduction to the quinol. The second synthesis condenses pentamethoxy-benzene with α-bromo-β-phenyl-propionyl chloride to yield tetramethoxy-benzyl-coumaranone and oxidises it with nitric acid to the quinone. Their properties are different from methyl pedicinin and they do not undergo conversion into it. It is therefore concluded that methyl pedicinin should be given only the quinone chalkone formula and that the alternative formulations are not valid. Further the possibility of reversible isomeric change between chalkones and benzylcoumaranones does not find experimental support.
Volume 30 Issue 5 November 1949 pp 216-222
A convenient method of providing confirmation of the constitution of carthamidin and isocarthamidin is to convert them into herbacetin and tangeretin. The earlier claim of Bargellini to have prepared herbacetin tetramethyl ether by the oxidation of 2-hydroxy-3:4:6:4′-tetramethoxy chalkone with alkaline hydrogen peroxide could not be supported. This reaction yields the corresponding benzalcoumaranone and not flavonol in agreement with the behaviour of analogous and simpler chalkones having a methoxyl group in the 6-position. An example is described where even a methyl group in that position brings about the same result. However by the action of amyl nitrite and hydrochloric acid carthamidin and isocarthamidin tetramethyl ethers yield the corresponding flavonol derivatives.
Volume 30 Issue 5 November 1949 pp 265-270
Asaronic acid is conveniently prepared from 4-O-methyl-β-resorcylic acid and isovanillic acid by oxidatron with alkaline persulphate and subsequent methylation. Useful partial methyl ethers and mixed methyl-ethyl ethers are also made by adopting this method. Similarly asarylic aldehyde is obtained from 4-O-methyl-β-resorcylic aldehyde and isovanillin.
Volume 30 Issue 5 November 1949 pp 271-276
The stem bark of Prunus puddum yields sakuranetin (I
Volume 30 Issue 5 November 1949 pp 277-277 Erratum
Volume 30 Issue 6 December 1949 pp 333-341
It is suggested that phytochemical nuclear oxidation involves several processes. (1) A single stage direct process which is satisfactory for the para oxidation of flavones and related compounds, the model being Elbs persulphate oxidation method, has already been discussed in detail in Part XIII. (2) A multistage process, an aldehyde being an intermediate stage which subsequently undergoes oxidation (Dakin’s reaction), is illustrated by the recent synthesis of the flavonols, myricetin, robinetin and kanugin and essential oil components, elemicin and myristicin. Support for the existence of the stages can be obtained from a study of lichen acids. The mechanism of this process is discussed; it is quite suitable for ortho oxidations in flavones and related compounds, but the yields are rather poor in para-oxidations. Another multistage process involving ethylenic activity has been shown by Cook and others to be applicable to polycyclic hydrocarbons.
Volume 30 Issue 6 December 1949 pp 342-347
(1) Chrysin, (2) tectochrysin and (3) 5-O-methyl chrysin are subjected to the two stage oxidation process. All of them give good yields of the corresponding 8-aldehydes. In (2) the 8-position (para) is predominantly more reactive than the 6-position (ortho). In (1) and (3) the favourable influence of a hydroxyl and a methoxyl in the 5-position is exerted. The Dakin’s reaction gives poor yields if the product is a quinol and good yields if it is a catechol. Experiments with (1) and (2) lead to the conclusion that the two stage method is available for para oxidations though the yields are poor.
Volume 31 Issue 1 January 1950 pp 31-34
For the synthesis of 5∶6∶8-trihydroxy flavone (6-hydroxy primetin), the two stage ortho-oxidation process is applied to primetin monomethyl ether. A good yield of the 6-aldehyde is obtained, which undergoes oxidation to 5∶6-dihydroxy-8-methoxy flavone. Subsequent demethylation yields 6-hydroxy primetin. Its properties and reactions and derivatives are described.
Volume 31 Issue 2 February 1950 pp 140-140 Erratum
Volume 31 Issue 5 May 1950 pp 358-358 Erratum
Volume 32 Issue 1 July 1950 pp 17-24
A general method for the synthesis of the 7-methyl ethers of hydroxy flavones is described using as examples (1) tectochrysin, (2) genkwanin and (3) 7-O-methyl luteolin. It consists in preparing the corresponding 7-O-methyl flavanone and oxidising it with iodine. 7-O-Methyl eriodictyol is now made from (
Volume 32 Issue 1 July 1950 pp 25-28
3-Methyl-gallic and myristicic acids have been synthesised by new methods. For this purpose vanillic acid is converted into its 5-aldehyde and oxidised with alkaline hydrogen peroxide to yield 3-methyl-gallic acid. Esterification, methylenation and hydrolysis give rise to a good yield of myristicic acid.
Volume 32 Issue 2 August 1950 pp 110-113
Based on considerations of biogenesis asarone is now synthesised from isochavibetol by para nuclear oxidation with alkaline persulphate and subsequent methylation. Isochavibetol needed for this purpose is conveniently prepared by the condensation isovanillin with propionic anhydride and sodium propionate.
Volume 32 Issue 4 October 1950 pp 250-255
3-Hydroxy primetin has been synthesised starting with 3∶5-dihydroxy flavone and using partial methylation, para nuclear oxidation and final demethylation. During the last stage no isomeric change is noticed. This is in conformity with the behaviour of similar cases of flavonol derivatives and is different from the behaviour of analogous flavone derivatives. Orthooxidation of 3-hydroxy primetin leading to the synthesis of the lowest member of the gardenin series is found to proceed satisfactorily.
Volume 32 Issue 4 October 1950 pp 256-263
The constitution of prunetin as the 7-methyl ether of genistein is established by preparing its diethyl ether and showing that it is identical with 7-methoxy-5 ∶ 4′-diethoxy isoflavone obtained by independent synthesis. Prunetin itself has been synthesised by a method involving partial methylation of genistein using one mole of dimethyl sulphate. The theoretical considerations are discussed. The same procedure leads to a convenient preparation of sakuranetin.
Volume 32 Issue 5 November 1950 pp 342-347
Santal has been synthesised by methylating 5∶7∶3′∶4′-tetrahydroxy isoflavone with one mole of dimethyl sulphate. When three moles of dimethyl sulphate are employed santal dimethyl ether is obtained. An interesting observation has been made that demethylation of santal trimethyl ether under restricted conditions with hydriodic acid leads to the formation of a mixture of santal and nor-santal. They have been separated using aqueous sodium carbonate.
Volume 32 Issue 6 December 1950 pp 367-373
The sap-soluble pigments of plants consist of anthocyanins and a number of related groups of anthoxanthins. Any comprehensive theory of biogenesis should embrace all these groups. The theories of sequential and parallel origin are discussed. Based on chemical considerations with reference to certain methyl ethers and glycosides of anthoxanthins it is concluded that sequential origin should be recognised as playing a definite part though parallel evolution may be the major factor. Further, glycoside and ether formation may not be the last stages in evolution in all cases.
Volume 33 Issue 1 January 1951 pp 11-21
It is suggested that umbelliferone is a fundamental compound in the biogenesis of coumarins and that other important hydroxycoumarins involve further stages of oxidation. In support of this idea experiments are described for the preparation from umbelliferone of æsculetin by
Volume 33 Issue 3 March 1951 pp 142-147
Chromic acid oxidation of teloschistin triacetate yields 4:5-diacetyl-7-
Volume 33 Issue 3 March 1951 pp 148-150
Using the two stage process of ortho oxidation, 5:6-dihydroxy flavone has been made from 6-hydroxy flavone.
Volume 33 Issue 3 March 1951 pp 151-154
Para oxidation in the side-phenyl nucleus has now been investigated using potassium persulphate and 3′-hydroxy-3:5:7:4′:5′-pentamethoxy flavone obtained conveniently from cannabiscitrin. The resulting quinol on methylation yields 3:5:7:3′:4′:5′:6′-heptamethoxy flavone and on demethylation 6′-hydroxy myricetin which is the first example of a flavone having four hydroxyl groups in the side-phenyl nucleus.
Volume 33 Issue 3 March 1951 pp 168-172
The synthesis and identity of karanjin-
Volume 33 Issue 4 April 1951 pp 233-235
4:5:6-Trimethoxy-coumaranone is obtained from quercetagetol-tetramethyl ether by treatment with hydrobromic acid and methylation of the product. It is conveniently synthesised from 2:6-dimethoxy-quinol which undergoes Friedel and Craft’s reaction with chloracetyl chloride satisfactorily.
Volume 33 Issue 5 May 1951 pp 257-263
The study of daidzein derivatives provides further support to the conclusions already arrived at regarding the special features of partial methylation and demethylation in the isoflavone series. Partial methylation of daidzein gives a good yield of the 7-monomethyl ether (isoformononetin) and the formation of the isomeric formononetin could not be detected. The same 7-methyl ether is obtained most conveniently by the demethylation of daidzein dimethyl ether with hydrobromic acid and hydriodic acid. 5:7-Dihydroxy and di-methoxy isoflavones have also been examined with a view to compare them with corresponding flavones. 7-Methoxy-5-hydroxy isoflavone is obtained most readily by partial demethylation of dimethoxy isoflavone with hydriodic acid whereas chrysin dimethyl ether yields mostly chrysin under these conditions.
Volume 34 Issue 3 September 1951 pp 187-196
Two methods of synthesising isoflavonofurans of the angular type are examined. Starting from karanjic acid (VI) and passing through the intermediate (X), 2-methyl-isoflavono-7:8-furan (XI) is easily obtained. The alternative method which starts with 2-methyl-7-hydroxy-isoflavone (XII) and builds up the furan ring through the 8-aldehyde (XIII) is beset with difficulties. However if instead of the aldehyde, the corresponding ketone (8-acetyl derivative XVII) is employed the difficulties are eliminated and good yield of 2:
Our thanks are due to the Imperial Chemical Industries, Ltd., and the National Institute of Sciences of India for the award of a Fellowship to one of us (L. R. R.).
Volume 34 Issue 4 October 1951 pp 272-274
The white acetate of gossypol is conveniently prepared by employing acetyl chloride and pyridine in the cold for the acetylation. The use of acetic anhydride and a catalyst at elevated temperatures produces a high melting pyrone derivative.
Volume 35 Issue 1 January 1952 pp 34-44
Methods of nuclear oxidation are applied for the preparation of chromone derivatives, many of which have been required for the study of isomeric change. Just as in the flavone group the presence of a methoxyl (hydroxyl) in the 3-position prevents isomeric change from the 5:7:8 to the 5:6:7 arrangement of hydroxyl groups; in its absence the isomeric change takes place.
Volume 35 Issue 1 January 1952 pp 46-52
Using methods of nuclear oxidation 7:8-dihydroxy-2-methyl isoflavone, 5:7:8-trihydroxyisoflavone and 5:7:8-trihydroxy-2-methyl isoflavone and their derivatives have been prepared. Demethylation of the 5:7:8-trimethoxy isoflavones with or without a 2-methyl group does not produce isomeric change in the trihydroxy product. It could therefore be concluded that a phenyl group in the 3-position prevents this isomeric change just like a methoxyl (hydroxyl) in the same position and that substitution in the 2-position has no influence.
Volume 35 Issue 2 February 1952 pp 75-81
A number of phenyl and halogen substituted coumarins with substituents in different positions have been examined as fish poisons. The presence of a phenyl group in the 3 or 4 position or a halogen atom in the 3-position seems to be most favourable. Higher substitution does not appreciably enhance the toxic properties. In consonance with previous results, a hydroxyl group in the 5-position seems to produce greater toxicity than one in the 7-position.
Volume 35 Issue 2 February 1952 pp 82-88
When boiled with hydriodic acid, 2:3-dimethyl-5:7:8-trimethoxy chromone undergoes besides demethylation, isomeric change also, yielding 2:3-dimethyl-5:6:7-trihydroxy chromone, thus showing that a free hydrogen atom in the 3-position is not essential for this isomeric change to take place and that the nature of the substituent is also important. For purposes of comparison, 2:3-dimethyl-5:7:8-trihydroxy chromone has been obtained by demethylation of the above trimethyl ether with aluminium chloride and 2:3-dimethyl-5:6:7-trimethoxy chromone by independent synthesis using nuclear oxidation as a stage.
Volume 35 Issue 4 April 1952 pp 202-209
Two new substances, padmakastin, a glycoside and padmakastein, the corresponding aglucone have been isolated from the bark of
Volume 35 Issue 5 May 1952 pp 233-241
Based on biogenetic considerations new syntheses of menaphthone and lawsone are given. From
Volume 35 Issue 5 May 1952 pp 242-248
An effective method for purifying apiin from parsley seeds is to convert it into the lead salt and recover it by decomposition with hydrogen sulphide. It then crystallises readily from alcohol and yields a crystalline acetate. The work on the complete methylation and hydrolysis has been revised using the pure sample and also purifying the methylated glycoside obtained as intermediate. The resulting 5:4′-
Extraction of the parsley plant grown in Delhi yielded only apiin as the anthoxanthin component and the presence of luteolin glycoside reported by von Gerichten could not be detected.
Volume 35 Issue 6 June 1952 pp 323-326
A new method of conversion of visnagin into kellin is described. It involves only three steps and gives much better yields. Nor-visnagin is subjected to nuclear oxidation with alkaline persulphate to yield nor-kellin which is conveniently methylated to kellin by means of dimethyl sulphate and potassium carbonate in acetone solution.
Volume 35 Issue 6 June 1952 pp 327-337
Typical examples from lichen acids illustrating the applicability of the methods of para and ortho oxidation are studied. They follow the schemes of biogenesis given earlier and are found to proceed satisfactorily, thus providing convenient methods of synthesis. The common origin of CH3, CH2OH, CHO, and COOH and also of a hydroxyl group is emphasised.
Volume 36 Issue 2 August 1952 pp 130-133
Of the two hydroxyl groups in the 2- and 6-positions of 2:3:6-trihydroxy-4-methoxy acetophenone and chalkone the 6-hydroxyl is shown to be more reactive. A modified biogenetic scheme is suggested for pedicin.
Volume 36 Issue 2 August 1952 pp 134-140
Use of N-bromo-succinimide for the conversion of flavanones into flavones is investigated. 7-Methoxy-flavanone undergoes bromination in the 3-position and on treatment with alcoholic sodium hydroxide solution gives rise to a good yield of 7-methoxy-flavone. On the other hand, 5:7-dimethoxy flavanone suffers nuclear bromination more prominently and yields a mixture of products containing 8-bromo-5:7-dimethoxy-flavanone and the 3:8-dibromo compound. Naringenin acetate yields as the major product apigenin acetate, as the result of substitution in the 3-position and subsequent elimination of hydrogen bromide; the other product is 3-bromonaringenin acetate which undergoes conversion into apigenin with alkali. Acetates therefore appear to be the most convenient derivatives for this reaction.
Volume 36 Issue 3 September 1952 pp 157-169
Circular Rf values of important synthetic flavonols have been determined using phenol saturated with water. The results have been used for analysing the flavonol composition of plant extracts, three typical examples being taken;
Volume 36 Issue 3 September 1952 pp 194-200
It is shown that the most convenient method of preparing prunetin is by the partial demethylation of genistein trimethyl ether with hydrobromic or hydriodic acid under controlled conditions. The 5-methyl ether of genistein (isoprunetin) has now been synthesised by the methylation of 7:4′-O-dibenzyl genistein and subsequent debenzylation. Its properties are very different from those of prunetin and it yields a diethyl ether which could be independently prepared from genistein. The present work conclusively proves that prunusetin cannot be 5-O-methyl genistein (isoprunetin) and should be the same as prunetin.
Volume 36 Issue 3 September 1952 pp 217-229
The methyl ethers of morin, resomorin and resodatiscetin have been made by different methods in order to examine the possible resistance of the 2′-hydroxyl group to methylation. No such resistance is found. 8-Hydroxy derivatives of morin, datiscetin and resodatiscetin have been prepared by employing methods of nuclear oxidation.
Volume 36 Issue 4 October 1952 pp 231-243
Volume 36 Issue 5 November 1952 pp 355-362
3:7:2′-5′-Tetrahydroxy flavone and 3:5:7:2′:5′-pentahydroxy flavone and their derivatives are prepared and their colour reactions recorded. The flavone with only 2′-hydroxyl free (X) and also its 5′-hydroxyl derivative (XI) do not give any colour with ferric chloride indicating absence of chelation. Alkali colour reactions confirm the original finding that a quinol grouping in the side phenyl nucleus does not produce marked colour effects.
Volume 37 Issue 1 January 1953 pp 127-144
A review of ring isomeric change of flavones and chromones is made as also of the reactivity of C-hydroxy phloroglucinol and C-hydroxy phloracetophenone derivatives in methylation, benzoylation and ring closure. The results are consistent showing the greater reactivity of a hydroxyl group of the quinol unit as compared with that of the catechol unit. A tentative explanation is given.
A synthetic study has been made of the chromones of
An attempt has been made to develop a comprehensive scheme of biogenesis which includes all the five components occurring in
Volume 37 Issue 1 January 1953 pp 145-158
Okano and Beppu isolated a new isoflavone from soya bean and from its degradation reactions, they assigned to it the constitution of 8-methyl genistein. A synthesis of this compound starting from C-methyl phloroglucinol α-monomethyl ether was also reported by Shriner and Hull.
An easier method of synthesis of a compound of this structure has now been described, in which the main stage is the nuclear methylation of 2∶4∶6-trihydroxy-4′-methoxy phenyl benzyl ketone. The constitution of the product of this reaction is established by an independent synthesis from C-methyl phloroglucinol. Though this synthesis of 8-methyl genistein involves demethylation of its trimethyl ether with hydriodic acid, the absence of any rearrangement during this step has been established particularly by remethylation. The products of the present synthesis are found to be very different from the natural compound and its derivatives described by Okano and Beppu and therefore it is considered that the natural compound cannot have the constitution assigned to it.
Partial demethylation of 8-methyl genistein trimethyl ether with hydriodic acid gives rise to 8-methyl prunetin which on partial methylation yields 8-methyl-5-hydroxy-7: 4′-dimethoxy isoflavone. This is different from the C-monomethyl-O-dimethyl genistein obtained by Perkin and Horsfall by nuclear methylation of genistein. Therefore the product of Perkin and Horsfall may have the methyl group in the 6-position as suggested by earlier workers.
Volume 37 Issue 4 April 1953 pp 514-519
One of the substances occurring in soya beans has been considered by Okano and Beppu to be 5∶7∶2′-trihydroxy isoflavone (isogenistein), based on degradation studies. A compound of this structure has now been made starting from 2∶4∶6-trihydroxy-2′-methoxy phenyl benzyl ketone. Partial methylation, treatment with ethyl formate and sodium followed by demethylation yield the required isoflavone. Aluminium chloride in benzene solution is found to be a much better reagent than hydriodic acid for the above demethylation. The products of the present synthesis are found to be different from the natural compound and its derivatives. Therefore the natural compound cannot be an isoflavone of this constitution. The main degradation product, considered to be 2∶4∶6∶2′-tetrahydroxy phenyl benzyl ketone by Okano and Beppu differs considerably from a synthetic product of this constitution. Hence the natural compound cannot be a simple isoflavone or isoflavanone and should have a different structure.
Volume 37 Issue 4 April 1953 pp 520-525
Heating 2-hydroxy-3∶4∶6-trimethoxy-chalkone with hydrobromic acid yields instead of the expected 7-methoxy-5∶8-dihydroxy flavanone, the isomeric 7-methoxy-5∶6-dihydroxy flavanone. The same product is obtained by the partial demethylation of 2-hydroxy-4∶5∶6-trimethoxy chalkone. Attempts to prepare 5∶8-dihydroxy-7-methoxy flavanone by the reduction of the corresponding quinone again resulted in the formation of the isomeric 7-methoxy-5∶6-dihydroxy flavanone. The 5∶8-dihydroxy compound has been obtained by the partial demethylation of 5∶7∶8-trimethoxy flavanone by means of aluminium chloride in nitrobenzene solution.
Volume 37 Issue 4 April 1953 pp 526-530
One of the crystalline compounds occurring in soya beans has been considered by Okano and Beppu to be 8-methyl isogenistein and this structure was based on the alkali degradation of the compound and its trimethyl ether. A compound of this structure is now synthesised starting from 2∶4∶6-trihydroxy-2′-methoxy phenyl benzyl ketone, along the lines of synthesis of 8-methyl genistein described in Part XXII. Here also the products are found to be different from those reported by Okano and Beppu and the natural compound should therefore have a more complex structure.
Volume 37 Issue 4 April 1953 pp 531-533
The partial demethylation of 5∶7∶3′∶4′-tetramethoxy isoflavone has now been effected under improved conditions and an almost quantitative yield of santal obtained. Partial methylation of nor-santal has been repeated using larger quantities and santal and its acetate prepared and studied.
Volume 37 Issue 4 April 1953 pp 534-543
A number of hydroxy and methoxy coumarin acetic acids have been prepared by the method of Dey and Row with a view to convert them into the corresponding coumaryl styrenes. Except the simplest of them,
Volume 37 Issue 4 April 1953 pp 544-550
Polyhydroxy benzadehydes are prepared by nuclear oxidation of
Volume 37 Issue 5 May 1953 pp 592-598
Earlier investigations have shown that partial methylation of the 7-position of 6∶7-dihydroxy coumarin is definitely possible. Claims were made by Schmid that in 5∶7-dihydroxy-4-methyl coumarin also partial methylation takes place in the 7-position. But no proof was provided. This has now been given by the ethylation of the partial methyl ether and subjecting it to nuclear oxidation and final ethylation. The product is found to be 7-methoxy-5∶6-diethoxy-4-methyl coumarin which has also been made by an independent and unambiguous method for purposes of comparison. The constitution of the partial methyl ether is thus established as 7-methoxy-5-hydroxy-4-methyl coumarin.
Volume 37 Issue 5 May 1953 pp 599-610
Past records indicate that an 8-hydroxyl group in a flavone is involved in chelation but it is of a weak nature. 7-Methoxy-8-hydroxy flavanone can be easily obtained by the partial methylation of 7∶8-dihydroxy flavanone or the partial demethylation of 7∶8-dimethoxy flavanone, and can also be directly obtained from gallacetophenone-4-methyl ether. Its preparation and properties indicate the existence of stronger chelation involving the 8-hydroxyl group. Similar experiments have been done on the preparation of 7-methoxy-8-hydroxy chromone and isoflavone. Though the partial demethylation of 7∶8-dimethoxy compounds has been successful, partial methylation of the dihydroxy compounds has not been possible in these cases. The properties of the products also indicate weaker chelation in the chromone and isoflavone just as in the corresponding flavone. In the course of the synthesis of 7-methoxy-8-hydroxy flavanone and chromone independently for purpose of comparison the preparation of the intermediate gallacetophenone 4-methyl ether has been re-investigated and a convenient method has been worked out.
Volume 37 Issue 5 May 1953 pp 611-619
The synthesis of 5∶7∶2′-trihydroxy and 5∶7∶2′∶4′-tetrahydroxy flavones has been repeated using Allan-Robinson condensation and both hydriodic acid and anhydrous aluminum chloride as demethylating agents. With these reagents and under ordinary conditions isomeric change involving the 2′-hydroxyl group does not occur. The tetrahydroxy flavone has also now been prepared by the procedure of Algar
Volume 37 Issue 5 May 1953 pp 620-628
For the preparation of flavanones having a 2′-methoxy group the acid method of chalkone condensation employing benzoates of hydroxy ketones is convenient. 5-Hydroxy-2′-methoxy flavanone and 5∶7-dihydroxy-2′-methoxy flavanone have thus been prepared. By demethylating the former with aluminium chloride 5∶2′-dihydroxy flavanone is obtained which undergoes only partial methylation in the 5-position even with excess of the reagent confirming that the 2′-hydroxyl is highly resistant. Synthetic 5∶7-hydroxy-2′-methoxy flavanone and its derivatives made by us and by Shinoda and Sato agree, but they do not agree in their properties with natural citronetin and its derivatives.
5-Hydroxy-2′-methoxy flavone does not undergo isomeric change under ordinary conditions of demethylation. 5∶2′-dihydroxy flavone undergoes partial methylation smoothly in the 2′-position thus showing the existence of marked difference between flavanones and flavones.
Volume 37 Issue 5 May 1953 pp 681-696
Volume 37 Issue 6 June 1953 pp 705-709
In their behaviour towards alkaline hydrogen peroxide 2′-methoxy chalkones behave normally and yield flavonols if the 6-position is free and benzalcoumaranones if this position has a methoxyl group. On the other hand 2′-hydroxy flavanones, and 5-hydroxy flavanones remain unaffected. This result is explicable on the basis that these hydroxy flavanone structures are stable and do not undergo change into the corresponding chalkone structures which alone suffer oxidation.
Volume 37 Issue 6 June 1953 pp 710-717
A new synthesis of hydroxy xanthones and their derivatives is described. It employs the Friedel and Craft’s reaction for the condensation of an ortho methoxy benzoyl chloride with a fully methylated polyhydric phenol. The resulting benzophenone has an ortho hydroxyl group which in a test case has been shown to belong to the phenol part. By subsequent treatment with aluminium chloride or hydriodic acid demethylation and xanthone ring closure are effected. As examples the synthesis of 1∶3-dihydroxy xanthone, 3∶4-dihydroxy xanthone and gentisein is given. The naturally occurring xanthone, gentisin is conveniently obtained by the partial methylation of gentisein or by the partial demethylation and ring closure of 2-hydroxy-4∶6∶2′∶5′-tetramethoxy benzophenone.
Volume 37 Issue 6 June 1953 pp 718-729
Fresh flowers are found to be much more satisfactory for getting a true picture of the flavonoid composition than dried ones. The following fresh flowers have now been examined. (1)
Volume 37 Issue 6 June 1953 pp 784-797
The evolution of the chromano-chromanone unit present in rotenone and related compounds is of much interest. From a consideration of a number of structures occurring in nature, it is suggested that 2-hydroxy-methyl-2′-hydroxy isoflavanone or its equivalent is an intermediate and it undergoes ring closure by dehydration.
Based on this hypothesis, a synthesis of 7-hydroxy-chromeno-(3′∶4′; 2∶3)-chromone has now been achieved. 2-Methyl-7∶2′-diacetoxy isoflavone is converted into a 2-bromomethyl compound by treatment with N-bromo succinimide. On hydrolysis and treatment with potassium carbonate in acetone, it yields 7-hydroxy-chromeno-(3′∶4′∶2∶3)-chromone.
Though attempts to prepare the required diacetoxy isoflavone directly from 2∶4∶2′-trihydroxy phenyl benzyl ketone have not been successful, it could be obtained starting from 2∶4-dihydroxy-2′-methoxy phenyl benzyl ketone and treatment of the intermediate 2-methyl-7-acetoxy-2′-methoxy isoflavone with aluminium chloride in benzene solution, followed by acetylation.
Methylation of 2-methyl-7∶2′-dihydroxy isoflavone with excess of methyl iodide gives rise to the 7-methyl ether, indicating the existence of a considerable difference in the reactivities of the 7 and 2′-hydroxyl groups. The negative ferric reaction of these 2′-hydroxy compounds shows absence of chelation.
Volume 37 Issue 6 June 1953 pp 798-804
In the presence of potassium carbonate or potash, acetone forms an addition product with 2∶6-dimethoxy quinone. Its properties and reactions are described. They give evidence for the presence of an aliphatic hydroxyl group and a ketone carbonyl. The combination is considered to involve addition of the acetone molecule at the C=O group in the 4-position of the quinone. Methyl ethyl ketone also forms a similar addition compound. Other simple
Volume 38 Issue 1 July 1953 pp 77-83
The synthesis of carajuridin chloride and carajurin has been carried out starting with 6-O-methyl phloroglucinaldehyde, preparing 2:4:5-trihydroxy-6-methoxy benzaldehyde as an intermediate and condensing the latter with
Volume 38 Issue 2 August 1953 pp 122-127
The synthesis of isodaidzein and of its methyl ethers has been carried out and their properties studied. The special features noticed earlier in the case 2′-hydroxy isoflavones are also found here and they seem to be characteristic of the presence of the 2′-methoxy and hydroxy groups in isoflavones.
Volume 38 Issue 3 September 1953 pp 207-219
Volume 38 Issue 4 October 1953 pp 288-293
7-Hydroxy-5:8:4′-trimethoxy flavylium chloride has now been prepared and subjected to demethylation with hydriodic acid. The resulting flavylium iodide and the colour-base (Isocarajuretin) and the flavylium chloride obtained from it, are different from carajuretin and its salts. Hence it is concluded that no isomeric change takes place during the demethylation of derivatives of 5:7:8-hydroxy-flavylium salts related to flavones, supporting the constitution of carajurin, given by Chapman, Perkin and Robinson.
Volume 38 Issue 4 October 1953 pp 294-296
Partial methyl ethers of chrysin, apigenin, galangin and quercetin have been subjected to nuclear reduction in the 5-position through their tosyloxy compounds. The products are 7-methoxy flavone, pratol methyl ether, 3:7-dimethoxy flavone and fisetin tetramethyl ether respectively.
Volume 38 Issue 5 November 1953 pp 381-386
It is established that the condensation of 2-hydroxy-4:6:2′-trimethoxy phenyl benzyl ketone and its 3-methyl derivative with ethyl formate as well as with methyl formate produces the corresponding 2-hydroxy isoflavanones. These undergo dehydration to the trimethyl ether of isogenistein and 8-methyl isogenistein respectively. Demethylation of the above ethers can be conveniently effected by aluminium chloride in benzene solution. The 2-hydroxy isoflavanones also yield the same products by undergoing dehydration along with demethylation.
Volume 38 Issue 6 December 1953 pp 467-469
By the application of nuclear reduction a quercetin derivative has been converted into kæmpherol and a kæmpherol derivative into galangin.
Volume 38 Issue 6 December 1953 pp 470-473
Nuclear reduction of 7-hydroxy and 5-hydroxy flavones yields
Volume 38 Issue 6 December 1953 pp 480-494
The two higher analogues of 5-hydroxy flavone (primuletin) containing two and three methoxyl groups in the side phenyl nucleus have been synthesised and subjected to persulphate oxidation. 5-Hydroxy-3′:4′-dimethoxy flavone gave poor yield of dimethoxy primetin while the higher member could not be oxidised under these conditions. Alternatively, oxidation of 8-hydroxy flavones has been attempted and found to proceed more satisfactorily to yield primetin and its higher members. The required 8-hydroxy flavones have been made from 2:3-dihydroxy acetophenone for the preparation of which a convenient method has been worked out starting from ortho vanillin.
Volume 39 Issue 1 January 1954 pp 45-52
The condensation of 1: 2: 3: 5-tetrahydroxy benzene with anisoyl acetaldehyde takes place in an abnormal way and gives rise to 5: 7: 8-trihydroxy-4′-methoxy flavylium chloride. By using 2: 6-dibenzyloxy quinol, 5: 7-di-benzyloxy-6-hydroxy-4′-methoxy flavylium chloride is obtained and subsequent debenzylation yields carajurone hydrochloride; by the action of sodium acetate, the colour-base carajurone is obtained.
Volume 39 Issue 3 March 1954 pp 144-152
Starting from antiarol a convenient synthesis of 2-methyl-5: 6: 7-trimethoxy (trihydroxy) and 5: 6: 7: 4′-tetramethoxy isoflavones has been carried out. The intermediate ketones are satisfactorily obtained by the Friedel and Craft’s reaction. Since the tetramethoxy isoflavone is identical with tectorigenin trimethyl ether the constitution of tectorigenin as a monomethyl ether of 5: 6: 7: 4′-tetrahydroxy isoflavone is thus confirmed. The location of the methoxyl group is again fixed as 6- by complete ethylation of tectorigenin and synthesis of this triethyl ether by a method analogous to the one described for the trimethyl ether.
Volume 39 Issue 4 April 1954 pp 165-175
Using the more easily accessible 5:7: 8-trihydroxy derivatives of isoflavones a convenient method has been worked out for the synthesis of 5: 6: 7-trihydroxy derivatives. It consists in the alkali fission of 5-hydroxy-7: 8-dimethoxy isoflavone and its 2-methyl derivative to yield 2: 6-dihydroxy-3: 4-dimethoxy-phenyl-benzyl ketone. This ketone on treatment with ethyl formate and sodium yields 5-hydroxy-6 : 7-dimethoxy isoflavone. Vigorous acetylation of the ketone using acetic anhydride and sodium acetate yields 2-methyl-5-hydroxy-6: 7-dimethoxy isoflavone which is compared with an authentic sample prepared by an independent method. 5-Hydroxy-7 : 8-dimethoxy isoflavone yields a small quantity of 5-hydroxy 6: 7-dimethoxy isoflavone during alkali fission.
Volume 39 Issue 5 May 1954 pp 254-263
The action of iodine and silver acetate varies with the type of flavanones employed, and yields the intermediate stages postulated in the new flavone synthesis using iodine and sodium acetate. The polyhydroxyflavanones, naringenin and hesperetin form directly the 3-acetates which can be hydrolysed to the 3-hydroxy compounds. On the other hand from naringenin 7:4′-dimethyl ether and 5:7-dimethoxy flavanone, the 3-iodo compounds can be isolated as the first intermediates. The behaviour of the 3-hydroxy flavanones in acid and alkaline conditions also varies; either dehydrogenation to flavonol or dehydration to flavone taking place.
Our thanks are due to Dr. Pew of the Forest Products Laboratory, Madison, U.S.A., for the generous supply of 3-hydroxy naringenin used in this work.
Volume 39 Issue 6 June 1954 pp 296-300
Starting from 2-hydroxy-3: 6-dimethoxy acetophenone a new synthesis of 3-hydroxy primetin has been effected and by alkali fission of the trimethyl ether 2-hydroxy-ω: 3: 6-trimethoxy acetophenone has been prepared. Using the same procedure (modified Kostanecki’s method) 3:5:8:3′: 4′-pentahydroxy flavone, its pentamethyl ether and penta-acetate have been obtained. The properties of these compounds are different from those of the pentahydroxy flavone and its derivatives obtained from Ponderosa Pine Bark.
Volume 40 Issue 6 December 1954 pp 249-259
3-Methoxy-7-hydroxy flavone does not undergo nuclear methylation. Nuclear methylation of (1) 3-O-methyl galangin and (2) 3:4′-O-dimethyl kaempferol has been shown to take place in the 6-position. As an intermediate in the case of (1) 3-O-methyl-6-C-methyl galangin has been isolated. The minimum structural requirements of this reaction and its mechanism are discussed.
Volume 41 Issue 5 May 1955 pp 210-223
A number of 3-hydroxy flavanones occur in nature and several have been obtained using a number of synthetic methods. Though they behave generally in the same way when subjected to drastic methods of dehydrogenation or dehydration, those obtained by substitution of flavanones in the 3-position seem to differ markedly from others in their reactions towards mild reagents such as dilute sulphuric acid and iodine. This is attributed to stereo-chemical differences. In this particular synthetic method the 3-hydroxyl is axial (H2O elimination easy) whereas in the others it is equatorial (H2 elimination easy). In flavanones substitution of the axially disposed C-H is the favoured one because it is sterically unhindered.
Volume 42 Issue 1 July 1955 pp 36-40
Using N-bromosuccinimide, a synthesis of 7∶7′-dihydroxychromeno-(3∶′∶4′∶2∶3) chromone has been effected. 7∶2′∶4′-Triacetoxy-2-methyl isoflavone is brominated to give the 2-bromomethyl isoflavone which is cyclized, after hydrolysis, to the corresponding chromenochromone.
Volume 42 Issue 4 October 1955 pp 192-194
By the use of ethoxy acetyl chloride and pyridine at 0°, 7-hydroxychromeno-(3′∶4′∶2∶3)-chromone has been synthesised much more conveniently than by the earlier methods reported in the literature.
Volume 42 Issue 5 November 1955 pp 252-254
5∶6∶7∶8∶4′-Pentamethoxy flavanone has been synthesised. The product is different from ponkanetin which was given the above structure earlier by Ichikawa and Yamashita.
Volume 42 Issue 5 November 1955 pp 279-284
Nuclear methylation of phloracetophenone and 3-C-methyl phloracetophenone, under vigorous conditions yields 5-acetyl-1∶1∶3∶3-tetramethyl cyclohexen-(4)-ol-(4)-dione (2∶6) (III); the intermediate 3∶5-dimethyl compound could not be obtained. This method is convenient for the preparation of leptospermone (VI). Many natural products seem to be formed by the nuclear methylation of the carbonyl derivatives of phloroglucinol. Using lesser proportions of alcoholic potash lower methylation products are obtained; but 3∶5-dimethyl-phloroacetophenone could be isolated only in small quantities.
Volume 43 Issue 2 February 1956 pp 79-83
Of the two methods of obtaining 7-methyl ethers of 5∶6∶7-hydroxy isoflavones partial methylation employing sodium bicarbonate is more convenient. Thus 7-methoxy-5∶6-dihydroxy and 7-methoxy-5∶6∶4′-trihydroxy isoflavones have been prepared. These could be partially acetylated, methylated in the 5-position and finally deacetylated to yield 5∶7-dimethoxy-6-hydroxy isoflavone and muningin respectively.
Volume 44 Issue 1 July 1956 pp 1-5
2-Hydroxy-6-methoxy benzoic acid condenses with orcinol giving rise to (1) 1-hydroxy-3-methyl-8-methoxy xanthone and (2) 1: 8-dihydroxy-3-methyl xanthone. The second is also obtained from γ-resorcylic acid. The first undergoes nuclear oxidation with alkaline persulphate to yield ravenelin-8-methyl ether which is demethylated to ravenelin.
Volume 44 Issue 1 July 1956 pp 42-45
Teloschistin has been prepared from physcion, the essential stage being the ω-bromo compound obtained by the use of N-bromo-succinimide. The higher m.p. of 244–46° is now recorded both for the synthetic and for the natural sample purified through the acetate. Complete methylation of teloschistin requires the use of methyl iodide and silver oxide at the final stage.
Volume 44 Issue 4 October 1956 pp 223-227
By the Friedel and Craft’s reaction using resorcinol dimethyl ether and
Volume 44 Issue 5 November 1956 pp 284-286
A new glucoside has been isolated from the flowers of
Volume 44 Issue 6 December 1956 pp 418-422
Starting from chrysophanol and frangula-emodin the corresponding ω-hydroxy compounds, alœ-emodin and citreorosein have been prepared adopting the N-bromosuccinimide method. Partial methylation of frangulaemodin to physcion is effected most conveniently by the methyl sulphatepotassium carbonate method. Physcion can be demethylated directly to frangula-emodin by long boiling with hydrobromic acid.
Volume 45 Issue 1 January 1957 pp 15-19
The position of the methoxyl group in dalbergin has been established by synthesis using two methods: (1) partial methylation of 4-phenyl-aesculetin and (2) nuclear oxidation of 4-phenyl umbelliferone methyl ether. By similar methods the 7-benzyl ether of 4-phenyl aesculetin and from it by methylation and debenzylation iso-dalbergin has been prepared. The ethyl ethers of dalbergin and iso-dalbergin have also been obtained.
Volume 45 Issue 5 May 1957 pp 293-297
Though the benzophenone method of synthesis is not quite advantageous for dalbergin and methyl dalbergin, it is more convenient for the preparation of allo-dalbergin (4-phenyl-5-methoxy-6-hydroxy coumarin) and its methyl ether. These compounds and other 4-phenyl coumarins give markedly coloured solutions when treated with alcohol, hydrochloric acid and magnesium; a number of 4-methyl coumarin derivatives also give similar colour reactions. On the other hand 3-phenyl and 3-phenyl-4-methyl coumarin derivatives do not respond to this test which may therefore be of diagnostic value.
Volume 46 Issue 1 July 1957 pp 19-24
A number of α-methyl-furano-flavones and their dihydro derivatives have been prepared using 7-hydroxy-8-allyl flavone derivatives. Ring closure is effected with anhydrous hydrogen bromide followed by pyridine and dehydrogenation with N-bromosuccinimide. 2-Methyl cromone derivatives have also been made. Tests with fish of select compounds indicate that dihydrofurano compounds are better poisons and an α-methyl group reduces toxicity in the furano compounds.
Volume 46 Issue 1 July 1957 pp 25-28
Cyanidin has been prepared in satisfactory yields from the acetates of (+) catechin and (-) epicatechin by monobromination with N.B.S. and subsequent treatment.
Volume 46 Issue 3 September 1957 pp 218-223
A comparative study of hydroxy-benzopyrone derivatives has been made with reference to their capacity to form chelate combinations with metals. Based on the determination of stability constants it could be concluded that 1-hydroxy xanthone forms the most stable complex. Addition of a methoxyl group in the 3-position has a favourable influence. Among the flavones a hydroxyl group in the 5-position forms definitely a stronger complex as compared with the 3-hydroxyl group. Here also addition of a methoxyl group in the 7-position is an advantage. Similar results are obtained with the chromones though their complexes are comparatively weaker. Isoflavone derivatives unexpectedly form the weakest complexes and in this case steric factors seem to be involved. The presence of this factor could be noticed in the case of 2: 3-diphenyl chromones also which also have abnormally weak complexes.
Volume 46 Issue 3 September 1957 pp 238-244
Anhydrous aluminium chloride in ether solution is found to be a convenient reagent for the selective demethylation of the 5-position of methoxy flavanones and these 5-hydroxy compounds can serve as standard derivatives for comparison. A number of typical compounds are reported, the most important being naringenin dimethyl ether, citronetin monomethyl ether and carthamidin and isocarthamidin trimethyl ethers. The method has been employed for the synthesis of dihydrowogonin which has been recently isolated. This involves the preparation and partial demethylation of 7-hydroxy-5:8-dimethoxy flavanone.
Volume 46 Issue 4 October 1957 pp 265-271
8-Methyl baicalein has been made (1) from 8-methyl chrysin by the preparation of the 6-aldehyde and subsequent Dakin’s reaction and (2) from C-methyl phloracetophenone dimethyl ether by steps involving persulphate oxidation and flavone ring closure. The isomeric 6-methyl compound has been obtained by the nuclear methylation of norwogonin and demethylation with aluminium chloride. The methyl ethers of the former undergo only demethylation when boiled with hydriodic acid whereas those of the latter undergo isomeric change besides demethylation.
Volume 46 Issue 5 November 1957 pp 343-348
On the consideration that stillopsidin is 5-hydroxybutein, butein trimethyl ether has been subjected to nuclear oxidation and final methylation to yield stillopsidin tetramethyl ether. Stillopsidin has now been prepared in better yields by an improved method. The product obtained by the partial demethylation of 2: 4: 5-trimethoxyacetophenone is shown to be 2: 5-dihydroxy-4-methoxyacetophenone which has been prepared by an unequivocal method from pæonol. Similarly an authentic sample of 2: 5-dihydroxy-4-methoxy-benzophenone has been prepared and shown to be the same as that obtained by the partial demethylation of 2: 4: 5-trimethoxybenzophenone. A synthesis of 2:4-dihydroxy-5-methoxyacetophenone has also been carried out.
Volume 47 Issue 3 March 1958 pp 184-190
A modified procedure for the action of iodine and silver acetate gives rise to purer products. Agreeing with earlier observations, hesperetin gives a good yield of 3-acetoxy hesperetin and hesperetin 7∶3′-dimethyl ether yields the 3-iodo-compound. The iodoflavanones invariably yield the corresponding flavones by the action of pyridine. In the treatment with alcoholic potash, those which have a free 5-hydroxyl,
Volume 47 Issue 3 March 1958 pp 191-195
A new and convenient method for the synthesis of tamaraxetin uses hesperetin. By the action of iodine and silver acetate, it is converted into 3-acetoxy-hesperetin and eventually into 3-hydroxy-hesperetin which undergoes dehydrogenation by means of iodine and potassium acetate to yield tamaraxetin.
5-Hydroxy-7-methoxy-flavanone (pinostrobin) is converted into alpinone by Fenton’s oxidation and subsequent dehydrogenation yields izalpinin.
Volume 47 Issue 4 April 1958 pp 230-237
In order to get fuller information on the influence of hydroxyl groups on alkali colour reactions a number of flavonols of types uncommon in Nature have been prepared and examined. Though the correlation between structure and alkali colour reactions is complex, when applied with care the reactions can be used for diagnostic purposes. The alkali colour reactions of the flavonols with 2′∶3′ and 2′∶3′∶4′ disposition of hydroxyl groups are not prominent and their fluorescence properties are also very feeble.
Volume 47 Issue 4 April 1958 pp 238-243
1-Hydroxy-3-methoxy xanthone forms a complex ThL4 in aqueous alcoholic solution at pH 2·6–4·0 and it can be precipitated with water, dried and ignited to yield thorium dioxide. This provides a satisfactory method of estimation of the metal in the presence of a large excess of cerite earths and ceric salts since these are not precipitated by this reagent and also in the presence of uranium which gets precipitated only at higher pH. The method can be used for separation also.
Volume 47 Issue 5 May 1958 pp 292-294
Starting from 7-hydroxy chromeno-chromone, the 8-allyl derivative has been prepared as intermediate and the α-methyl furan ring closed by means of hydrogen bromide and pyridine, yielding the five-ring structure of α-methyl dihydro-furano-chromeno-chromone.
Volume 48 Issue 4 October 1958 pp 175-179
The synthesis of padmakaste in has been effected by the catalytic reduction of prunetin diacetate and subsequent deacetylation. Similarly prunetin dimethyl ether yields padmakastein dimethyl ether. The natural and synthetic samples have been compared.
Volume 48 Issue 4 October 1958 pp 180-189
Nuclear methylation of 2:4-dihydroxy-chalkones (III) give rise to 3-C-methyl derivatives just as in the case of resacetophenone. C-Methylchalkone-derivatives (IV) with substituents in the side phenyl nucleus have also been prepared by this method. For comparison, they have been synthesised using 3-methyl-peonol and appropriate derivatives of benzaldehyde. C-Methyl-
The flavanone, naringenin, when subjected to nuclear methylation under mild conditions yields 6-methyl-flavanone derivative (VIII) whereas under conditions in which the oxygen ring opens, beside the above 6-methyl flavanone (VIII), poly-C-methylated chalkones (XII
Volume 49 Issue 1 January 1959 pp 1-5
A sample of
Volume 49 Issue 1 January 1959 pp 47-53
Leucodelphinidin (flavan-diol, I B) under mild conditions of acetylation and another leucodelphinidin (flavan-diol, I A) under more drastic conditions yield the same flav-3-ene-3-ol acetate which produces delphinidin chloride in much better yields than the original diols. Products of reductive acetylation of flavonols agree with flav-3-ene-3-ol acetates in important respects. Reductive acetylation of dihydro-quercetin yields the same product as that of quercetin. Quercetin pentamethyl ether suffers similar reduction under the same conditions. It is therefore concluded that reductive acetylation reduces both the ethylenic and carbonyl groups and is followed by loss of the elements of water.
Volume 49 Issue 2 February 1959 pp 104-110
The two important characteristics of 4-phenyl coumarin derivatives,
Volume 49 Issue 4 April 1959 pp 234-240
2-Methylanthraquinones with the 1∶4-dihydroxy system are conveniently prepared by the persulphate oxidation of the intermediate benzoylbenzoic acids and subsequent ring closure. 2-Methylquinizarin, islandicin and cynodontin have been prepared by this method as typical examples.
Volume 50 Issue 3 September 1959 pp 192-195
In the case of nor-wogonin and 5:7:8-trihydroxy-2-methylchromone, Gattermann method is efficient in yielding the corresponding aldehydes, whereas with their 8-methyl ethers hexamine method works satisfactorily.
Volume 51 Issue 6 June 1960 pp 296-300
A convenient synthesis, following suggested path of biogenesis, of catenarin and erythroglaucin has been made. It involves nuclear oxidation of the corresponding benzoyl benzoic acid. This reaction and the following ring closure give very good yields of catenarin dimethyl ether. Complete demethylation yields catenarin and partial demethylation erythroglaucin which can also be formed by the partial methylation of catenarin.
Volume 62 Issue 5 November 1965 pp 293-306
For the action of iodine and silver acetate on flavanones to take place, the nature and position of substituents are important. The presence of either a 5-hydroxyl or a 5-methoxyl is essential for any reaction to occur. A free hydroxyl in the 7-position is inhibitory even for iodination of 5-hydroxyflavanone derivatives. Complete methyl ethers yield 8-iodocompounds; whereas 5-hydroxy-7-methoxyflavanones afford a mixture of 3-iodo and 8-iodo derivatives. Simple 5-hydroxy-flavanone forms 3, 8-di-iodo and 2, 3-di-iodo-5-hydroxy flavanones. 5-Hydroxy-7, 4′-diacetoxy-flavanone undergoes iodination only in the pyranone part to yield 2, 3-di-iodo and 3-iodo derivatives; substitution in the benzene ring is inhibited. It is suggested that the 5-hydroxyl by chelation with the carbonyl increases the activity of the methylene group in the 3-position.
Volume 66 Issue 1 July 1967 pp 1-14
The ultraviolet and infrared spectral data for a number of lichen depsides, depsidones and their fission products have been recorded. The U.V. spectra of the orcinol depsides, orcinol depsidones and
Volume 68 Issue 6 December 1968 pp 314-323
New data presented regarding the influence of different types of substituents in the benzene ring of aromatic carbonyl compounds (including benzils) on the > C=O frequency have made it possible to revise and rationalise older explanations.
Based on uniform considerations of polarisation, rational explanation can be provided for the effects of ethylene and phenyl conjugation, hydrogen bond formation and complex formation. Abnormal effects are observed in special cases where other important factors are simultaneously involved as for example in N-oxides and flavonoids of various types; but they are explicable on a rational basis. Further, the behaviour of acetylene and nitrile compounds throws insight on the nature of some of these factors.
Volume 69 Issue 1 January 1969 pp 66-66 Erratum
Volume 78 Issue 4 October 1973 pp 141-148
The effect of chelation on the carbonyl frequency of xanthones is to lower it just as in the case of flavanones, isoflavanones and simpler ketones. This supports the explanation given earlier regarding the special behaviour of flavones and isoflavones. Benzophenones and anthraquinones resemble xanthones in this respect.