Articles written in Proceedings – Section A
Volume 3 Issue 1 January 1936 pp 206-210
Volume 3 Issue 3 March 1936 pp 206-210
Volume 23 Issue 5 May 1946 pp 278-282
It has been shown that 6-hydroxyflavone couples with diazo salts in the 5-position. 5-Benzeneazo-6-hydroxyflavone has been reduced to 5-amino-6-hydroxyflavone. Treatment of the latter with nitrous acid gave flavone-5-diazo-6-oxide, hydrolysis of which with boiling dilute sulphuric acid led to 5∶6-dihydroxyflavone.
The utility of the general procedure for the synthesis of other polyhydroxyflavones and methoxyhydroxyflavones is being studied.
Volume 25 Issue 5 May 1947 pp 438-443
1∶7-Dihydroxy-3-methoxyxanthone has been synthesised and shown to be identical with natural gentisin. 7-Nitro-1 ∶ 3-dihydroxyxanthone, obtained by a Hoesch reaction between 5-nitrosalicylonitrile and phloroglucinol, followed by hydrolysis and cyclicisation, was methylated by diazomethane to its 3-methyl ether. This, on reduction, diazotisation, and hydrolysis with sulphuric acid, gave 3-methoxy-1 ∶ 7-dihydroxyxanthone, identical in all its properties with natural gentisin.
Volume 25 Issue 5 May 1947 pp 467-479
1-Aminoanthraquinone-2-aldazine (V), prepared by the action of hydrazine on 1-aminoanthraquinone-2-aldehyde or anthraquinone-1: 2-isoxazole, and identified as the commercial vat dye, Indanthrene Bordeaux B, undergoes an interesting series of degradations. The colour and stability of the dye molecule are due to resonance effects, and on diazotising the amino groups the molecule breaks down readily, yielding 1-substituted derivatives of 1-amino-anthraquinone-2-aldehyde. It has been noticed that other aldazines and anils undergo facile fission on treatment with sodium nitrite and sulphuric acid.
Volume 26 Issue 5 November 1947 pp 279-287
Hydroxyflavone can be prepared from nitroflavone by reduction, diazotisation and hydrolysis. The utility of this general procedure has been shown by the synthesis of 4′-hydroxy-α-naphthaflavone, 7∶4′-dihydroxyflavone, 4′-hydroxy-7-methoxy-flavone and 5∶4′-dihydroxy-7-methoxyflavone (genkwanin). Puddumetin, isolated from
Volume 27 Issue 2 March 1948 pp 121-127
Various extracts of the leaves of
Volume 27 Issue 4 April 1948 pp 265-274
Volume 28 Issue 3 September 1948 pp 111-124
The constitution (V) proposed by Fierz-David for Hydron Blue, in which polymerisation of the thiazine from carbazole-indophenol through disulphoxide linkages is postulated, does not take into account the necessity of polymerisation through the positions marked by asterisks in (V) to account for the dyeing property of Hydron Blue. The fact that polymerisation of thionated carbazole-indophenol units does not proceed through carboncarbon linkages has been proved by the identity of the reduction products from carbazole-indophenol and from Hydron Blue, obtained by treatment with Raney nickel. The formation of the glycollic acid (XVIII) from the thiazone (XV) indicates the possibility of reaction between the phenolic groups in leuco-Hydron Blue and chloracetic acid. If disulphoxide linkages were present in Hydron Blue (V) and its analogues, such as Pyrogen Indigo (IV), the condensation of their leuco-derivatives with chloracetic acid should have given tetra-acetic acid derivatives corresponding to the two thiol and the two phenolic groups in their leuco-compounds (
Volume 28 Issue 3 September 1948 pp 142-150
Treatment of sulphur-containing heterocyclic compounds such as thiodiphenylamine (I) and benzidine-sulphone (II) with Raney nickel in a suitable solvent gave the sulphur-free compounds diphenylamine and N∶N′-diethylbenzidine (reduction in ethyl alcohol).
β-Naphthol gave a mixture of 1∶2∶3⪉-tetrahydro-2-naphthol and 5∶6∶7∶8-tetrahydro-2-naphthol on reduction with Raney nickel in alcoholic alkaline solution. Naphthol AS (2-hydroxy-3-naphthanilide) yielded 5∶6∶7∶8-tetrahydro-2-hydroxy-3-naphthanilide and J-acid gave 6-amino-1-naphthol on treatment with Raney nickel.
Carbazole was unaffected when treated with Raney nickel in morpholine, but gave tetrahydrocarbazole when reduced in alcohol. 3-Chloro- and 3-aminocarbazole also gave tetrahydrocarbazole on reduction in alcohol and dioxan respectively.
Anthraquinone and 2-methylanthraquinone gave octahydro-derivatives on reduction in alcohol. Reduction in morpholine and in aqueous alkali gave several reduction products which are under investigation.
Volume 28 Issue 4 October 1948 pp 151-159
4-Hydroxynaphthocoumarin has been synthesised by the internal condensation of
Volume 28 Issue 4 October 1948 pp 160-165
6-7-Benzocoumaranone was first described by Ullmann who prepared it by the cyclization of 2-bromacetyl-1-naphthol and recorded the m.p. 91–2°. Fries prepared it later by the intramolecular acylation of α-naphthoxyacetyl bromide and recorded the m.p. 119°. A compound of the same m.p. prepared similarly from α-naphthoxyacetyl chloride has been considered by Ingham
Volume 28 Issue 4 October 1948 pp 236-252
Attempts to determine the orientation of the chlorine atoms in some of the commercial chlorinated indanthrones and in the dichloroindanthrones prepared by the action of antimony pentachloride and sulphuryl chloride on indanthrone and by the action of hydrochloric acid on anthraquinoneazine are described. The higher reactivity of the chlorine atoms in the direct chlorinated indanthrones suggests α-orientation. The dichloro-indanthrone (IIA) from antimony pentachloride is distinguished from the other chloroindanthrones obtained by direct chlorination by its greater resistance to azine formation on treatment with oxidising agents. The 4∶4′-orientation is, therefore, suggested for the chlorine atoms in (IIA), and substitution in the 5, 8, 5′, 8′ positions in the other direct chlorinated indanthrones. Antimony pentachloride was found to be specific in introducing two chlorine atoms in indanthrone. 4∶4′-Di-
2∶4-Dichloro-1-aminoanthraquinone has been prepared by an improved method and its utility as a dyestuff intermediate has been studied. A few other halogenated aminoanthraquinones and their acyl dervatives which do not appear to have been described in literature have been synthesised.
Volume 28 Issue 6 December 1948 pp 545-555
The utility, as azoic coupling components, of diketones prepared by the action of sodamide and similar reagents on
We are grateful to Imperial Chemical Industries (Dyestuffs Group) and to the Sir Dorab Tata Trust for the award of research fellowships to two of us. We are also thankful to Mr. T. S. Gore for carrying out the microanalyses.
Volume 29 Issue 3 March 1949 pp 196-202
Starting from 4-nitro-
Volume 29 Issue 3 March 1949 pp 203-209
The Algar-Flynn oxidation of
Volume 29 Issue 5 May 1949 pp 289-308
The constitution (I) proposed in 1931 by Coyne, Raistrick and Robinson for citrinin, an antibiotic produced by
In the chromatographic adsorption of
Volume 30 Issue 1 July 1949 pp 1-11
The invalidity of the constitution (I), proposed by Fierz-David and Geering, for Cibanone Yellow R, a dye which is noted for its catalytic activity in the photochemical degradation of cellulose, is discussed. The purified dye, assumed to be homogeneous by Fierz-David, has been shown to be a mixture of several substances by chromatographic adsorption on alumina. The major tinctorial constituent crystallized from acetylene tetrachloride in curved needles, m.p. 368–70°. Anthraflavone was among the other products isolated.
Elementary analysis of pure Cibanone Yellow R is in agreement with the empirical formula C45H26O7S, corresponding to three methylanthraquinone residues for one atom of sulphur. Reductive desulphurisation of the pure dye by treatment with Raney nickel and pyrolysis with zinc dust indicate that 2-methylanthraquinone residues are linked together through the methyl groups by means of sulphur, as against the methylene bridge between anthraquinone groups in the constitution (I) proposed by Fierz-David. The structure (IV) is suggested for pure Cibanone Yellow R.
Volume 30 Issue 2 August 1949 pp 1- Erratum
Volume 32 Issue 1 July 1950 pp 29-38
The orientation of the nitro groups in dinitrodibenzanthrone produced by nitration of dibenzanthrone has not been established so far. The suggestion of Simonsen
Derivatives of 3∶3′-dibenzanthronyl of definite orientation are useful as intermediates for the corresponding dibenzanthrone derivatives. Thus the dinitrodibenzanthronyl (VI) has been converted to 3∶12-dichloro- and 3∶12-diaminodibenzanthrone.
Volume 32 Issue 1 July 1950 pp 39-45
9-Aminobenzanthrone, which has been prepared earlier by a tedious synthesis, has now been prepared from 3-bromobenzanthrone by nitration to 3-bromo-9-nitrobenzanthrone, reduction of the nitro derivative to 3-bromo-9-aminobenzanthrone, and debromination of the latter compound by palladium and hydrazine. 3∶12-Diaminodibenzanthrone (VIII) was formed as a minor product in the debromination.
While the angular orientation of the fused pyridine ring in benzanthronequinoline, a product obtained by the action of glycerine and sulphuric acid on 2-aminoanthraquinone, has been established, the relative positions of the benzene and pyridine rings has not been proved so far. The Skraup reaction on 9-aminobenzanthrone gave benzanthronequinoline, thus proving its constitution as (IV). Cyananthrene, a vat dye obtained by alkali fusion of benzanthronequinoline, is therefore constituted as (X), and not as (IX) as sometimes stated in the literature.
Volume 32 Issue 3 September 1950 pp 162-170
The action of Raney alloy and aqueous alkali on thioindigo, 6∶6′-diethoxythioindigo and thioindoxyl has been studied with the result that a new method for the preparation of diphenacyl and its derivatives has become available. Other products which were isolated were benzoic acid and 1∶4-diphenylbutane; the latter was formed when excess of Raney alloy was used. 6∶6′-Diethoxythioindigo gave 4∶4′-diethoxydiphenacyl (V) in 79% yield and
4∶4′-Diethoxydiphenacyl has been converted into 2∶5-
Volume 32 Issue 4 October 1950 pp 201-211
Indanthrene Turquoise Blue GK and 3GK have been shown to be 11-chloro-6-aminoanthraquinoneacridone (II) and 10∶12-dichloro-6-aminoanthraquinoneacridone (III) respectively by unambiguous synthesis. The absorption spectra of the commercial and the synthetic dyestuffs have been determined. Chloro derivatives of 6-aminoanthraquinoneacridone, substituted by chlorine in the anthraquinone nucleus, in the benzene half of the molecule, and in both the anthraquinone and the benzene halves, have been synthesised, and the fastness properties of the shades on cotton determined. 6-Aminoanthraquinoneacridone has been prepared by a new route; the various chloro derivatives of 6-aminoanthraquinoneacridone which have been synthesised are the 7-, 10-, and 11-monochloro, 7∶10-, 7∶11- and 10∶12-dichloro, the 7∶10∶12-trichloro and 11-chloro-7-bromo-compounds. It is found that the acridones containing a chlorine atom in the 7-position, adjacent to the amino group, are dehalogenated by treatment with aqueous alkali and hydrosulphite at room temparature (28°) for about one hour.
Volume 32 Issue 4 October 1950 pp 240-249
Hydrolysis of Indanthrene Yellow 4GK gives 8-aminopyrimidanthrone (II) and 2∶5-dichlorobenzoic acid; the dye is therefore the 8-(2′∶5′-dichloro)-benzamidopyrimidanthrone (I). Indanthrene Yellow 7GK is the
Unlike many yellow and orange anthraquinonoid vat dyes, Indanthrene Yellow 4GK and 7GK do not accelerate the photochemical oxidation of cellulose. Differences in the behaviour of anthraquinone derivatives and of pyrimidanthrone derivatives in the action of light on cellulose are explained on the basis of the relative stability of their semiquinone ions.
Volume 32 Issue 5 November 1950 pp 292-303
The bromination of the anilide,
The monobromo derivative of the
The N-6-bromo-2-hydroxy-3-naphthoyl derivatives of aniline,
All the brominated “naphthols” synthesized in the present work are characterized by the brightness and excellent fastness properties of the azoic shades.
Volume 32 Issue 5 November 1950 pp 348-351
The constitution (I), assigned by Howard and Raistrick1 to islandicin, the coloring matter from the dried mycelium of
3-Nitro-2-(5′-benzeneazo-2′-hydroxy-4′-methyl)-benzoylbenzoic acid (VII), obtained by coupling 3-nitro-2-(2′-hydroxy-4′-methyl)-benzoylbenzoic acid (VI) with diazotized aniline, gave on reduction 3-amino-2-(5′-amino-2′-hydroxy-4′-methyl)-benzoylbenzoic acid (VIII). The latter was converted in one step to 1∶4∶5-trihydroxy-2-methylanthraquinone (I) by tetrazotization and treatment with hot sulphuric acid. The properties of (I), its triacetate and its trimethyl ether are identical with those of islandicin, its triacetate and its trimethyl ether described by Howard and Raistrick.
Volume 32 Issue 6 December 1950 pp 357-366
3∶5-Diiodosalicylic acid, 4-amino-
The behaviour of 4-aminosalicylic acid towards diazonium salts has been investigated.
Volume 33 Issue 1 January 1951 pp 56-65
1. The bacteriostatic properties of sulphanilamide and five N1-substituted sulphanilamides, and of three anionic surface-active compounds, have been studied, singly and together, against the organisms,
2. With incubation temperatures of 37° and 43° the concentration of sulphanilamide for bacteriostasis in peptone medium is independent of the age of the culture and the concentration of the inoculum at the higher temperature only. In the synthetic medium, the effects of age of cells and size of inocula are less pronounced at both temperatures of incubation.
3. The minimum effective concentrations of sulpha drugs needed for growth inhibition are more in peptone broth than in the synthetic medium. Similar but less pronounced differences are seen with the surface-active compounds against
4. While the surface-active compounds are by themselves ineffective against the Gram-negative organisms, they have potentiating activity with the sulpha drugs.
5. The synergic effects of sulphanilamide and surface-active compound are unaltered even when the organism is rendered resistant to sulphanilamide or when the antibacterial property of the surface-active compound is neutralized by lecithin.
Volume 33 Issue 2 February 1951 pp 116-126
A synthesis of the naturally occurring isoflavone prunetin (5:4′-dihydroxy-7-methoxyisoflavone) is described. 5:7-Dimethoxy-4′-nitroisoflavone (IX) was prepared by the action of ethyl orthoformate, pyridine and piperidine on 2-hydroxy-4:6-dimethoxyphenyl 4-nitrobenzyl ketone. The nitro compound was reduced to the amine, which was diazotized and boiled with sulphuric acid. 4′-Hydroxy-5:7-dimethoxyisoflavone thus obtained was demethylated in the 5-position by means of aluminium chloride in nitrobenzene. The product, 5:4′-dihydroxy-7-methoxyisoflavone agreed in all its properties with prunetin, as well as prunusetin. The latter, isolated by Chakravarti from
7-Hydroxyisoflavone can be prepared by the action of sodium and ethyl formate on benzyl 2:4-dihydroxyphenyl ketone, protection of the 4-hydroxyl group not being necessary; but under the same conditions of reaction 5:7-dihydroxyisoflavone was not obtainable from benzyl 2:4:6-trihydroxyphenyl ketone. Partial methylation of the latter to benzyl 2-hydroxy-4:6-dimethoxyphenyl ketone, followed by treatment with sodium and ethyl formate, led readily to 5:7-dimethoxyisoflavone. Demethylation with hydriodic acid gave 5:7-dihydroxyisoflavone, while the action of hydrobromic acid in acetic acid yielded 5-hydroxy-7-methoxyisoflavone.
Volume 33 Issue 4 April 1951 pp 228-232
Santal, a constituent of sandelwood (
Volume 34 Issue 5 November 1951 pp 304-315
The synthesis of 4-chloro-, bromo- and iodo- alizarins is described. Bromination of 2-
Volume 34 Issue 6 December 1951 pp 355-367
The relation between chemical constitution and chromatographic adsorbability of a series of aminoanthraqunones and their derivatives has been investigated. Of the various types of interaction of which alumina appears to be capable in the process of adsorption, the most important is hydrogen bonding between alumina and one or more proton-donor groups in the adsorptive. When anthracene, anthraquinone and a series of aminoanthraquinones and their derivatives are chromatographed on alumina, using benzene as solvent for adsorption and development, the strength of adsorption is in the following increasing order: anthracene, anthraquinone, N-methyl-1-aminoanthraquinone, 1-benzamidoanthraquinone, 1:4-bis-methylaminoanthraquinone, 1-aminoanthraquinone, 1:5-diaminoanthraquinone and N-methyl-2-aminoanthraquinone, 1:8-diaminoanthraqunione, N-methyl-1-benzamidoanthraquinone and N-methyl-2-benzamidoanthraquinone, 2-aminoanthraquinone, 1:4-diaminoanthraquinone, 1:4:5-triaminoanthraquinone, 1:2-diaminoanthraquinone, 1:4:5:8-tetraminoanthraquinone, 2:6-diaminoanthraquinone. The relative adsorption affinities are explained in terms of chelation between NH2 and CO groups, resonance interaction between NH2 and CO groups, the ability of amide groups to form hydrogen bonds, and the electron-repulsive effect of methyl groups.
Volume 34 Issue 6 December 1951 pp 368-386
The relative adsorption affinities of monoazo derivatives of phenol and resorcinol have been explained on the basis of chelation and of the availability of hydroxyl and azo groups for interaction with alumina. Since Ruggli has shown that monoazo, disazo and trisazo dyes are adsorbed in the given increasing order of strength of adsorption, an observation of special interest, explained by chelation effects, is that
When phenol is coupled with a molar proportion of diazotized aniline,
2-Benzeneazoresorcinol has been prepared by coupling diazotized aniline with dimethyl resorcinol-4:6-dicarboxylate, followed by hydrolysis and decarboxylation. 4-Benzeneazoresorcinol, 4:6-bisbenzeneazoresorcinol, 2-benzeneazoresorcinol, and 2:4-bisbenzeneazoresorcinol are adsorbed on alumina in the given order of decreasing strength of adsorption. Examining the crude dye obtained by coupling resorcinol with benzenediazonium chloride by chromatography on alumina in the light of the above observations, it is shown that, contrary to statements in the literature, there is no evidence of the formation of 2-benzeneazoresorcinol.
Although the γ- or 2-position of 5-substituted resorcinols has considerable reactivity in reactions such as carboxylation and the Fries rearrangement, the first coupling of orcinol with diazotized aniline takes place entirely in the 4-position. The second coupling takes place in the 2- or 6-position according as the pH is 5⊋ash;8 or higher.
Resacetophenone couples with diazotized aniline to a mixture of 5-benzeneazo-and 3:5-bisbenzeneazoresacetophenone; the constitution of the former was shown by the Fries rearrangement of the diacetate to 2:4-diacetyl-6-benzeneazoresorcinol. The failure of resacetophenone to undergo the first coupling in the γ-position shows the weakness of the hydrogen bond between the carbonyl and adjacent hydroxyl groups, as well as a marked difference in the influence of such chelation on the Fries rearrangement and on diazonium coupling.
Volume 35 Issue 4 April 1952 pp 159-165
Volume 36 Issue 6 December 1952 pp 552-558
5:7:2′-Trihydroxyisoflavone and 5:7:2′-trihydroxy-8-methylisoflavone have been synthesized, and have been found to be different respectively from “isogenistein” and “methylisogenistein” isolated by Okano and Beppu from soya bean.
As a preliminary to the synthesis of 5:4′-dihydroxy-8-methylisoflavone, which Okano and Beppu have stated to be the probable structure of tatoin, another constituent of soya bean, 5-hydroxyisoflavone has been synthesized.
Volume 37 Issue 5 May 1953 pp 629-642
Synthetical experiments in the chromone group - Part XXVII. Coupling of 5-hydroxyflavone, 5-hydroxy-6-methoxyflavone and tectochrysin with diazotized aniline. New synthesis of 5∶6-dihydroxyflavone, baicalein, and 5∶6∶8-trihydroxyflavone
The coupling of 5-hydroxyflavone with benzenediazonium chloride led to an azo dye which was different from the compound obtained by the Robinson flavone condensation on 2-acetyl-4-benzeneazoresorcinol and benzoic anhydride. The two compounds are shown to be the 8- and 6-benzeneazo derivatives of 5-hydroxyflavone respectively. The conversion of both the azo dyes into 5∶6-dihydroxyflavone is described.
Tectochrysin was converted to baicalein 7-methyl ether by coupling with benzenediazonium chloride, followed by reduction of the azo dye to the amine and treatment of the latter with hydrochloric acid. Baicalein was obtained by demethylation of the 7-methyl ether. The same series of reactions carried out on 5-hydroxy-6-methoxyflavone25 led to 5∶6∶8-trihydroxyflavone.
Volume 37 Issue 5 May 1953 pp 660-663
In the course of exploratory experiments on the synthesis of muningin 6-hydroxy-5∶7-dimethoxyisoflavone (I) has been synthesized by the action of ethyl orthoformate, pyridine and piperidine on 2∶5-dihydroxy-4∶6-dimethoxyphenyl benzyl ketone (III). The ketone (III) was prepared by the interaction of 2∶6-dimethoxyhydroquinone and the boron trifluoride complex of phenylacetic acid. Demethylation of (I) with hydriodic acid gave 5∶6∶7-trihydroxyisoflavone (IV).
Volume 38 Issue 1 July 1953 pp 23-30
In view of the activity of
Volume 38 Issue 1 July 1953 pp 40-44
A general method for the preparation of 5-hydroxyflavone and its derivatives from the corresponding 5:7-dihydroxyflavones by the action of Raney nickel on the 7-tosyloxy derivatives is described. Thus chrysin has been converted into 5-hydroxyflavone, and galangin 3-methyl ether to 5-hydroxy-3-methoxyflavone.
Volume 38 Issue 2 August 1953 pp 161-175
Reduction of anthraquinone, 2-methylanthraquinone, 2-mercaptomethylanthraquinone (I),
Dehydrogenation of tetrahydro- and tetrahydromethylanthraquinones to the parent compounds was effected by several methods including treatment with iodine and sodium acetate in nitrobenzene and the action of activated alumina on a hexane solution. Treatment of tetrahydroanthraquinone with selenium dioxide at 170° gave a mixture of anthraquinone, α-hydroxyanthraquinone and quinizarin. Decahydroanthraflavone was dehydrogenated in two steps to Anthraflavone.
Volume 38 Issue 3 September 1953 pp 244-256
Desulphurization of the following thioindigoid dyes has been studied: Durindone Red B, Durindone Orange R, Durindone Red 3BS, Durindone Brown GS, Ciba Brown 2R and Ciba Scarlet G. The action of Raney alloy in aqueous alkali gave diphenacyl derivatives in most cases together with further reduction products, such as 1:4-diaryl-1:4-butanediols and 1:4-diaryl-1-butanol. Reduction of the dyes with Raney nickel in alcohol gave 1:4-diarylbutanes as the major products. The chlorine atoms in Durindone Red 3BS were partially or completely removed during the reduction. The constitution of Ciba Brown 2R was proved by reduction and the dye was shown to be identical with Durindone Brown GS. The constitution of the diphenacyls was proved by conversion to 1:4-diarylfurans and by synthesis. The constitution of 1:4-diarylbutanes was proved by oxidation to the corresponding benzoic acids. Reduction of 2:3′-bis-thionaphthene-indigo gave an alcohol, probably constituted as 2:4-diphenyl-1-butanol.
Mild reduction of thioindoxyl gave acetophenone, thioindoxylic acid gave
The constitution assigned earlier to 1:2-benzo- and 3:4-benzo-9-thiafluorenes was confirmed by their desulphurization to
Volume 38 Issue 4 October 1953 pp 297-306
A qualitative method for assigning the longest wavelength band in the absorption spectra of
Volume 38 Issue 4 October 1953 pp 307-319
The absorption spectra of dibenzanthrone, 16: 17-dihydroxydibenzanthrone, 16: 17-and 3: 12-dimethoxydibenzanthrone have been determined in
The absorption spectra of 3:3′- and 4:4′-dibenzanthronyls have been reported and discussed.
Volume 38 Issue 5 November 1953 pp 355-360
From the product of the benzanthrone condensation on 2-chloroanthraquinone 4-chlorobenzanthrone, identical with the substance obtained by the Sandmeyer reaction on 4-aminobenzanthrone, has been isolated. Chromatographic analysis of a benzene solution of the residue on alumina gave 9-chlorobenzanthrone. The residue after separation of 9-chlorobenzanthrone contains the 10-isomer. 2-Chloroanthraquinone-1-carboxylic acid, prepared by chromic acid oxidation of 4-chlorobenzanthrone, has m.p. 280–81°, and not 176–77°, as stated in the literature. For comparison with the anthraquinone carboxylic acids obtained by oxidation of chlorobenzanthrones, 3-chloroanthraquinone-1-carboxylic acid has been prepared from 1-amino-3-chloroanthraquinone
Volume 38 Issue 5 November 1953 pp 361-366
5-Nitrobenzanthrone has been synthesized by nitration of 4-acetamidobenzanthrone, hydrolysis to 4-amino-5-nitrobenzanthrone and subsequent deamination. The adjacent orientation of the amino and nitro groups was shown by reduction to a diamine, which formed a quinoxaline with phenanthraquinone and an imidazole with benzoyl chloride. Reduction of 5-nitrobenzanthrone gave 5-aminobenzanthrone which was converted to 5-chlorobenzanthrone. Oxidation of 5-chlorobenzanthrone gave 3-chloroanthraquinone-1-carboxylic acid, identical with the acid prepared from 1-amino-3-chloroanthraquinone.
Volume 38 Issue 6 December 1953 pp 474-479
1:3-Dichloroanthraquinone has been prepared by the deamination of 1-amino-2:4-dichloroanthraquinone. The dichloroanthraquinone is useful for the preparation of 1-amino-3-chloroanthraquinone.
Volume 39 Issue 2 February 1954 pp 90-97
By Raney nickel hydrogenolysis of the 7-tosyl ester (V), 5:7-dihydroxy-3: 3′:4′-trimethoxyflavone (IV) has been converted into 5-hydroxy-3:3′:4′-trimethoxyflavone (VI). Persulphate oxidation of (VI) gave 5: 8-dihydroxy-3: 3′:4′-trimethoxyflavone (VII), which was demethylated to 3:5:8:3′:4′-pentahydroxyflavone (III) by means of aluminium bromide in benzene. This pentahydroxyflavone was different in its properties from ponderosin, the yellow colouring matter of
Volume 41 Issue 5 May 1955 pp 192-201
2:5-Dihydroxy-4:6-dimethoxyphenyl benzyl ketone (I) described earlier as a yellow oil, b.p. 230–50°/1 mm., has now been obtained as yellow prismatic needles, m.p. 108°. The acid-boron trifluoride complex method is of general use for the synthesis of phenolic ketones; 2-hydroxy-4:5:6-tri-methoxyphenyl 4-methoxybenzyl ketone (II), 2-hydroxy-5-ethoxy-4:6-di-methoxyphenyl 4-ethoxybenzyl ketone (III) and 2:5-dihydroxy-4:6-di-methoxyphenyl 4-methoxybenzyl ketone (IV) have thus been prepared. The cyclization of (II) with ethyl orthoformate gave 5:6:7:4′-tetramethoxy-isoflavone, which was then demethylated to 5:6:7:4′-tetrahydroxyisoflavone (V). Partial demethylation of 5:6:7:4′-tetramethoxyisoflavone to 5-hydroxy-6:7:4′-trimethoxyisoflavone and 5:6:4′-trihydroxy-7-methoxy-isoflavone (VI) has been effected.
Treatment of (VI) in acetone with benzoyl chloride (2 mol.) and potassium carbonate gave 6 : 4′-dibenzoyloxy-5-hydroxy-7-methoxyisoflavone (VII), methylation of which yielded 6:4′-dibenzoyloxy-5:7-dimethoxyisoflavone (VIII). The m.p. of (VIII) was not depressed by mixing with the dibenzoyl derivative prepared from natural muningin by means of benzoyl chloride and potassium carbonate in acetone. Hydrolysis of (VIII) with 2% methanolic caustic potash at 30° and acidification gave 6:4′-dihydroxy-5:7-dimethoxyisoflavone, identical with natural muningin. The ditosyl analogues of (VII) and (VIII) were similarly prepared.
Ethyl orthoformate cyclization of the ketone (III) gave muningin diethyl ether, and cyclization of the ketone (IV) yielded muningin 4′-methyl ether.
Volume 42 Issue 6 December 1955 pp 336-341
7-Aminoflavone has been synthesized in view of its relationship to 4-aminosalicylic acid (PAS) and the reported antitubercular activity of flavone.
By heating 2-hydroxy-4-nitroacetophenone with benzoyl chloride and potassium carbonate in acetone
Volume 44 Issue 1 July 1956 pp 36-41
A synthesis of tectorigenin (5: 7: 4′-trihydroxy-6-methoxyisoflavone), which occurs as the 7-glucoside (tectoridin) in the rhizome of Iris tectorum, is described. 5: 7-Dihydroxy-6-methoxy-4′-nitroisoflavone (V) was prepared by the action of ethyl orthoformate, pyridine and piperidine on 2: 4: 6-trihydroxy-3-methoxyphenyl 4-nitrobenzyl ketone (IV). The fact that cyclization of the ketone (IV) proceeded in the desired direction to give the isoflavone (V), and not the isomeric 5: 7-dihydroxy-8-methoxy-4′-nitroisoflavone (VII), was shown by methylation, which yielded a substance different from 5: 7: 8-trimethoxy-4′-nitroisoflavone (IX); the latter (IX) was prepared by ethyl orthoformate cyclization of 2: 4-dihydroxy-3: 6-dimethoxyphenyl 4-nitrobenzyl ketone (X) to 7-hydroxy-5: 8-dimethoxy-4′-nitroisoflavone (XI), followed by methylation. The nitroisoflavone (V) was reduced to the amine (VI), which was diazotized and treated with boiling sulphuric acid. 5: 7: 4′-Trihydroxy-6-methoxyisoflavone (I) thus obtained agreed in all its properties with natural tectorigenin.