• K Venkataraman

      Articles written in Proceedings – Section A

    • Antiseptics and anthelminthics - Part II. A synthesis of 6-benzyl-7-hydroxyflavone and 6-n-hexyl-7-hydroxyflavone

      D R Dhingra Harminder Lal Uppal K Venkataraman

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    • Antiseptics and anthelminthics - Part II. A synthesis of 6-benzyl-7-hydroxyflavone and 6-n-hexyl-7-hydroxyflavone

      D R Dhingra Harminder Lal Uppal K Venkataraman

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    • Synthetical experiments in the chromone group - Part XX. A new synthesis of 5∶6 dihydroxyflavone

      R N Iyer K Venkataraman

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      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.

    • Synthetical experiments in the chromone group - Part XXI. Synthesis of gentisin, the colouring matter of gentian root

      Nity Anand K Venkataraman

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      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.

    • Anthraquinone series - Part I. 1-Aminoanthraquinone-2-aldazine

      S V Sunthankar K Venkataraman

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      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.

    • Synthetical experiments in the chromone group - Part XXII. Nitroflavones as intermediates for the synthesis of hydroxy- and hydroxymethoxyflavones

      Nity Anand K Venkataraman

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      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 fromPrunus puddum, has been proved to be identical with genkwanin.

    • Anthelminthics—Part III - Anthelminthic activity ofCalycopteris floribunda

      M L Khorana D K Motiwala K Venkataraman

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      Various extracts of the leaves ofCalycopteris floribunda have been prepared, and their toxicity to earthworms studied under standard conditions, in comparison with well-known anthelminthics. Calycopterin has been found to be more toxic to earthworms than santonin or oil of chenopodium, but less toxic than carbon tetrachloride, thymol, etc. Demethylation as well as methylation of calycopterin diminishes anthelminthic activity.

    • Sulphanilamides - Part I. Salts with sulphonic acids

      S K Munshi B D Tilak K Venkataraman

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    • Sulphur dyes and sulphurised vat dyes - Part I. Constitution of Hydron Blue

      K H Shah B D Tilak K Venkataraman

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      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 (e.g., XXII). Fierz-David, however, obtained a diacetic acid derivative from Pyrogen Indigo. Taking these facts into consideration, the constitution (XIII) is now proposed for Hydron Blue, in which polymerisation of thionated carbazole-indophenol units through sulphoxide linkages is postulated. Other analogous sulphurised indophenols can also be similarly constituted. The new constitution for sulphurised indophenol dyes readily accounts for the formation of a diacetic acid derivative from Pyrogen Indigo on the basis of the reaction between chloracetic acid and the phenolic groups in leuco-Pyrogen Indigo as in the case of the simple thiazone (XV).

    • Raney nickel reductions—Part I

      K H Shah B D Tilak K Venkataraman

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      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.

    • A new synthesis of 4-hydroxycoumarins

      Nity Anand K Venkataraman

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      4-Hydroxynaphthocoumarin has been synthesised by the internal condensation ofO-carbethoxy-2-acetyl-1-naphthol, thus suggesting a new general method for the synthesis of 4-hydroxycoumarins. The behaviour of 4-hydroxynaphthocoumarin has been studied; its derivatives including the corresponding dicoumarin have been prepared. By the action of potassium carbonate or sodamide on the carbethoxy ester of 2-acetyl-1-naphthol, a second product was obtained, the constitution of which is under examination.

    • 6∶7-benzocoumaranone

      Nity Anand K Venkataraman

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      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 Inghamet al., to beperinaphthapyrone. 6∶7-Benzocoumaranone, m.p. 119°, has now been synthesised by an unambiguous route, starting from 1-hydroxy-2-naphthoic acid through the intermediate diazoketone, and it has been shown that the product obtained by Inghamet al. was 6∶7-benzocoumaranone.

    • Anthraquinone series - Part II. Halogenated aminoanthraquinones and indanthrones

      S G Bedekar B D Tilak K Venkataraman

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      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-p-toluenesulphonamido-indanthrone (LV) has been synthesised.

      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.

    • Azoic dyes - Part IX. The behaviour of ω-benzoyl-2-acetyl-1-naphthol towards diazonium salts

      Nity Anand D M Patel K Venkataraman

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      The utility, as azoic coupling components, of diketones prepared by the action of sodamide and similar reagents ono-benzoyloxyaryl methyl ketones has been investigated. 2-benzoylacetyl-1-naphthol gives weak dyeings when used as a “naphthol” for impregnation of cotton, and development with diazonium salts. The shades lacked fastness to soaping and light. On coupling the diketone in substance with diazonium salts, mono-and disazo dyes were obtained; the constitution of the former, which could have two possible structures, has been proved to be 4-benzeneazo-2-benzoylacetyl-1-naphthol by an unambiguous synthesis from 4-benzeneazo-2-acetyl-1-naphthol through the corresponding benzoate. The monoazo dye from 1-benzoylacetyl-2-naphthol has been prepared. 4-benzamido-2-benzoylacetyl-1-naphthol and 4-acetoacetamido-2-acetyl-1-naphthol have also been studied as “naphthols”.

      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.

    • 3∶3′-Dihydroxyazobenzene-4∶4′-dicarboxylic acid and 4-aminosalicylic acid

      D S Bhate T B Panse K Venkataraman

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      Starting from 4-nitro-o-toluidine, a commercially available dyestuff intermediate, 4-aminosalicylic acid has been prepared in an overall yield of 60 per cent. New derivatives of the acid are described. 3∶3′-Dihydroxyazobenzene-4∶4′-dicarboxylic acid has been obtained from 4-nitrosalicylic acid, an intermediate in the synthesis of 4-aminosalicylic acid. This azo salicylic acid and its O-acetyl derivative are of interest on account of theirin vivo reducibility to 4-aminosalicylic acid and 4-aminoaspirin.

    • Synthetical experiments in the chromone group - Part XXIII. A new synthesis of rhamnazin and a synthesis of 3∶4′-dihydroxy-7-methoxyflavone

      Nity Anand R N Iyer K Venkataraman

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      The Algar-Flynn oxidation ofo′-hydroxychalkones to flavonols by means of alkaline hydrogen peroxide is applicable to chalkones with a hydroxyl group in the 4-position, irrespective of the presence of a methoxyl group in the 6′-position. Rhamnazin 5-methyl ether, and rhamnazin by partial demethylation with aluminium chloride, have thus been synthesized. Geissman and Fukushima have shown that 2′-hydroxy-6′-methoxychalkones give benzalcoumaranones, the flavonols not being formed or only as minor products. The influence of the 4-hydroxyl group on the course of the reaction is discussed.

    • Citrinin—Part I

      T S Gore T B Panse K Venkataraman

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      The constitution (I) proposed in 1931 by Coyne, Raistrick and Robinson for citrinin, an antibiotic produced byPenicillium citrinum, and the structures assigned to the product (A) of the sulphuric acid hydrolysis of citrinin and the dialkylresorcinol (C) obtained by alkali fusion of (A), have been shown to be untenable in view of their behaviour towards diazonium salts. The dialkylresorcinol (C) is 4-methyl-5-ethylresorcinol, and not 4-methyl-2-ethylresorcinol. From the orientation of the alkyl groups in (C) and the experimental results of Hetherington and Raistrick it follows that Product (A) is 4-methyl-5-(1-methyl-2-hydroxy)-propylresorcinol (IX), as suggested by Cram. Two alternative structures (X and XXV), which are both derived from an isochromane system and which differe from each other only in the position of the carboxyl group, are discussed; the action of diazonium salts on citrinin and on Product (A) is better explained by (XXV).

      In the chromatographic adsorption ofmono- andbis-benzeneazoresorcinols on an alumina column, 4-benzeneazoresorcinol is more strongly adsorbed than 2∶4− or 4∶6-bisbenzeneazoresorcinol, while Ruggli and Jensen have observed that the adsorbability of the azo dyes studied by them increased with the number of azo groups. 2-Benzeneazo-4-methylresorcinol is more weakly adsorbed than 6-benzeneazo-4-methylresorcinol. These effects are ascribed to chelation between the azo and hydroxyl groups.

    • Sulphur dyes and sulphurised vat dyes - Part II. Constitution of Cibanone Yellow R—Part I

      K H Shah B D Tilak K Venkataraman

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      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.

    • Erratum to: Citrinin — Part I

      T S Gore T B Panse Manhas K Venkataraman

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    • Anthraquinone and anthrone series - Part III. Constitution of dinitrodibenzanthrone and some derivatives of 3∶3′-dibenzanthronyl

      P N Pandit B D Tilak K Venkataraman

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      The orientation of the nitro groups in dinitrodibenzanthrone produced by nitration of dibenzanthrone has not been established so far. The suggestion of Simonsenet al.5 that the nitro groups are in the 3∶12-positions has been disproved by the unambiguous synthesis of 3∶12-diaminodibenzanthrone (IV), which was found to be different from the diamino derivative obtained by the reduction of the above dinitrodibenzanthrone. The diaminodibenzanthrone (IV) was synthesized from 3∶3′-dibenzanthronyl (V) by nitration to 9∶9′-dinitro-3∶3′-dibenzanthronyl (VI) and conversion of the latter in one step to (IV). The 9∶9′-orientation of the nitro groups in (VI) was shown by its oxidation to 6-nitroanthraquinone-1-carboxylic acid.

      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.

    • Anthraquinone and anthrone series - Part IV. Constitution of a benzanthronequinoline and of cyananthrene

      P N Pandit B D Tilak K Venkataraman

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      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.

    • Raney nickel reductions - Part II. Thioindigo, 6∶6′-diethoxythioindigo and thioindoxyl

      G N Kao B D Tilak K Venkataraman

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      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 andp-ethoxybenzoic acid. Thioindoxyl and acetophenone on similar treatment also gave benzoic acid.

      4∶4′-Diethoxydiphenacyl has been converted into 2∶5-bis-p-hydroxyphenylfuran (VII), 2∶5-bis-p-ethoxyphenylfuran (VI) and 1-p-chlorophenyl-2∶5-bis-p-ethoxyphenylpyrrole (VIII).

    • Anthraquinone and anthrone series - Part V. Chlorinated 6-aminoanthraquinoneacridones

      B S Joshi B D Tilak K Venkataraman

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      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.

    • Anthraquinone and anthrone series - Part VI. 6- and 8-benzamidopyrimidanthrones

      S V Sunthankar K Venkataraman

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      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 thep-chlorobenzoyl derivative (V) of 6-aminopyrimidanthrone (IV). The ability of a pyrimidanthrone derivative to function as a vat dye, although it possesses only one carbonyl group, results from an increase in the acid strength of the leuco compound by the resonance stabilization of the anion as indicated in structures (III A) and (III B).

      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.

    • Azoic dyes - Part X. Brominated naphthols

      R V Talavdekar K Venkataraman

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      The bromination of the anilide,o-anisidide andp-anisidide of 2-hydroxy-3-naphthoic acid has been studied. The orientation of the bromine atoms has been determined and the effect of bromination on the shades and the fastness properties of the azoic shades produced from the brominated “naphthols” has been examined. By bromination of the anilide, the first bromine atom enters the naphthalene nucleus in the 1-position, and this can be readily removed by reducing agents. The second bromine atom enters the benzene nucleus in the 4′-position, while the third bromine atom attacks the naphthalene nucleus in the 6-position. Bromination of theo-anisidide gives a mixture of products; the first bromine atom enters the naphthalene nucleus, while the second bromine atom attacks partly the 3- and partly the 4-position ino-anisidine. Tribromination also gives a mixture in which 1∶3′∶4′-tribromo-2-hydroxy-3-naphth-o-anisidide predominates.

      The monobromo derivative of thep-anisidide of hydroxynaphthoic acid, obtained by the partial debromination of its dibromo derivative, is a mixture of 6-bromo- and 2′-bromo-2-hydroxy-3-naphth-p-anisidide. The dibromo compound, obtained by the partial debromination of the tribromo derivative, is 6∶2′-dibromo-2-hydroxy-3-naphth-p-anisidide.

      The N-6-bromo-2-hydroxy-3-naphthoyl derivatives of aniline,o- andp-anisidine have been prepared by condensing 6-bromo-2-hydroxy-3-naphthoic acid with the amines.

      All the brominated “naphthols” synthesized in the present work are characterized by the brightness and excellent fastness properties of the azoic shades.

    • Anthraquinone and anthrone series - Part VII. A synthesis of islandicin

      B S Joshi B D Tilak K Venkataraman

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      The constitution (I), assigned by Howard and Raistrick1 to islandicin, the coloring matter from the dried mycelium ofPenicillium islandicum Sopp., has now been confirmed by unambiguous synthesis.

      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.

    • Antitubercular compounds - Part II. 3∶5-diiodo-4-aminosalicylic acid, 4-amino-O-acetylsalicylic acid and other derivatives of 4-aminosalicylic acid

      D S Bhate T B Panse K Venkataraman

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      3∶5-Diiodosalicylic acid, 4-amino-O-acetylsalicylic acid (aminoaspirin), and a series of ethers of 4-aminosalicylic acid have been prepared.

      The behaviour of 4-aminosalicylic acid towards diazonium salts has been investigated.

    • Sulphanilamides - Part II.In vitro synergism with anionic surface-active compounds

      M S Pavgi V C Sane A Sreenivasan K Venkataraman

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      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,S. aureus, E. coli, andE. typhosa, using peptone-broth and a synthetic medium.

      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 againstS. aureus.

      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.

    • Synthetical experiments in the chromone group - Part XXIV. A synthesis of prunetin

      R N Iyer K H Shah K Venkataraman

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      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 fromPrunus puddum, is therefore identical with prunctin.

      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.

    • Synthetical experiments in the chromone group - Part XXV. A synthesis of santal

      R N Iyer K H Shah K Venkataraman

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      Santal, a constituent of sandelwood (Pterocarpus santalinus Linn.) and of barwood (Baphia nitida Lodd.), has been shown by Robertson, Suckling and Whalley to be 5:3′:4′-trihydroxy-7-methoxyisoflavone. A synthesis of santal is now described. 5:7-Dimethoxy-3′:4′-methylenedioxyisoflavone (IV) has been prepared by the action of ethyl formate and sodium on 2-hydroxy-4:6-dimethoxyphenyl 3:4-methylenedioxybenzyl ketone at room temperature. By the action of aluminium bromide on (IV) in nitrobenzene under specified conditions, demethylenation and preferential demethylation in the 5-position were effected, and the product agreed in all its properties with santal.

    • Anthraquinone and anthrone series - Part VIII. 4-halogenoalizarins and their derivatives

      B S Joshi B D Tilak K Venkataraman

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      The synthesis of 4-chloro-, bromo- and iodo- alizarins is described. Bromination of 2-O-p-toluene sulphonylalizarin (I) in glacial acetic acid gave a monobromo derivative (II), which on hydrolysis yielded a new bromoalizarin (III). Methylation of (III) gave the known 4-bromoalizarin-2-methyl ether, showing that (III) is 4-bromoalizarin. Chlorination of (I) with sulphuryl chloride in nitrobenzene gave 4-chloro-2-O-p-toluene-sulphonylalizarin (XII), which on hydrolysis yielded 4-chloroalizarin. Condensation of (II) and (XII) with aniline andp-toluidine led to 4-anilino-and 4-p-toluidinoalizarins. In addition to the 4-arylaminoalizarins, 1:2:4-trianilino and 1:2:4-tri-p-toluidinoanthraquinones were isolated by chromatography. Condensation of 4-nitroalizarin with aniline in presence of boric acid gave 4-anilinoalizarin, which was different from the product described by Gonsalves,et al., as 4-anilinoalizarin. 6:7-Dihydroxyanthraquinoneacridone was prepared from (II) in the usual manner and examined as a vat dye. 4-Iodoalizarin-2-methyl ether (XV) was prepared from alizarin-2-methyl ether by nitration, reduction, and replacement of the amino group by iodinevia the diazonium salt. Demethylation of (XV) with aluminium chloride gave 4-iodoalizarin.

    • Anthraquinone and anthrone series - Part IX. Chromatographic adsorption of aminoanthraquinones on alumina

      N R Rao K H Shah K Venkataraman

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      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.

    • Chelation in azophenols in relation to chromatographic adsorbability on alumina

      T S Gore K Venkataraman

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      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 thatp-hydroxyazobenzene is more strongly adsorbed than 2:4-bisbenzeneazophenol, and that 4-benzeneazoresorcinol is more strongly adsorbed than 2:4- or 4:6-bisbenzeneazoresorcinol.

      When phenol is coupled with a molar proportion of diazotized aniline,o-hydroxyazobenzene,p-hydroxyazobenzene and 2:4-bisbenzeneazophenol are formed in yields of 1·1, 97·9 and 1% respectively. They are separable by chromatography on alumina, the adsorption affinity being in the following decreasing order:p-hydroxyazobenzene, 2:4-bisbenzeneazophenol, ando-hydroxyazobenzene.

      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.

    • Anthraquinone and anthrone series - Part X. Some derivatives of benzanthrone and dibenzanthrone

      P N Pandit B D Tilak K Venkataraman

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    • Synthetical experiments in the chromone group - Part XXVI. Synthesis of 5:7:2′-trihydroxyisoflavone, 5:7:2′-trihydroxy-8-methylisoflavone and 5-hydroxyisoflavone

      S S Karmarkar K H Shah K Venkataraman

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      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.

    • 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

      R N Iyer K Venkataraman

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      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.

    • Synthetical experiments in the chromone group - Part XXVIII. Synthesis of 6-hydroxy-5:7-dimethoxyisoflavone and 5:6:7-trihydroxyisoflavone 01

      S S Karmarkar K H Shah K Venkataraman

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      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).

    • Chloramphenicol series - Part I. Nitrophenyl alkyl sulphides, sulphoxides and sulphones

      A V Sunthankar B D Tilak K Venkataraman

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      p-Nitrophenyl bromomethyl sulphone (II) andp-nitrophenyl phthalimidomethyl sulphone (X) were prepared with the view to synthesize the sulphone analogue (I) of chloramphenicol. In contrast with the synthesis of chloramphenicol from analogous phenacyl derivatives, (II) and (X) could not be converted to (I) on account of the deactivating influence of the sulphone group in aryl methyl sulphones.

      In view of the activity ofp-nitrophenylω-hydroxyethyl sulphide, sulphoxide and sulphone, severalp-nitrophenyl alkyl sulphides, sulphoxides and sulphones and other related compounds were prepared.

    • Synthetical experiments in the chromone group - Part XXIX. A method for the reduction of 5:7-dihydroxyflavones to 5-hydroxyflavones

      V Ramanathan K Venkataraman

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      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.

    • Raney nickel reductions - Part III. Reduction of anthraquinone and its derivatives

      V Ramanathan B D Tilak K Venkataraman

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      Reduction of anthraquinone, 2-methylanthraquinone, 2-mercaptomethylanthraquinone (I),bis-2-anthraquinonylmethyl sulphide (II) andbis-2-anthraquinonylmethyl disulphide (III) by Raney alloy in aqueous alkaline solution was studied. Anthraquinone gave 1:2:3:4-tetrahydroanthraquinone. When 2-methylanthraquinone was reduced with varying amounts of Raney alloy, several hydro derivatives of 2-methylanthraquinone were obtained. One was 1:2:3:4-tetrahydro-6-methylanthraquinone, the constitution of which was proved by oxidation to adipic and 4-methylphthalic acids. Desulphurization of (I) gave 2-methylanthraquinone, 2-hydroxymethylanthraquinone and anthraquinone-2-carboxylic acid; (II) gave 2-methylanthraquinone and traces of Anthraflavone; and (III) gave 2-methylanthraquinone, 2-hydroxymethylanthraquinone and anthraquinone-2-carboxylic acid. Anthraflavone gave decahydroanthraflavone as the major product and a small amount of 1:2:3:4-tetrahydro-6-methylanthraquinone.

      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.

    • Raney nickel reductions - Part IV. Thioindigo dyes, thionaphthenes and thiafluorenes

      G N Kao B D Tilak K Venkataraman

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      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 gaveβ-phenyl-β-hydroxypropionic acid, together with dihydrocinnamic acid.

      The constitution assigned earlier to 1:2-benzo- and 3:4-benzo-9-thiafluorenes was confirmed by their desulphurization toβ- andα-phenylnaphthalene respectively by means of Raney nickel.

    • The effect of substitution on the light absorption of naphthalene

      M R Padhye N R Rao K Venkataraman

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      A qualitative method for assigning the longest wavelength band in the absorption spectra ofα- andβ-monosubstituted naphthalene derivative to polarizations in definite directions has been devised. The longest wavelength band in the absorption spectra ofα-substituted derivatives is shown to be due to polarization along the short axis of the molecule; in the spectra of theβ-substituted derivatives the longest wavelength band is due to polarization along the long axis of the molecule. The absorption spectra of four isomeric hydroxynaphthoic acids have been determined, using dioxane as solvent. The deeper colour of 2:3-hydroxynaphthoic acid in comparison with the isomeric acids is explained as due toβ:β-disubstitution in the naphthalene nucleus. The absorption spectra of 2-methoxy-1-naphthoic acid, 2-methoxy-3-naphthoic acid and 2-methoxy-6-naphthoic acid are discussed.

    • Anthraquinone and anthrone series - Part XI. Steric hindrance in dibenzanthronyls and dibenzanthrones

      M R Padhye N R Rao K Venkataraman

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      The absorption spectra of dibenzanthrone, 16: 17-dihydroxydibenzanthrone, 16: 17-and 3: 12-dimethoxydibenzanthrone have been determined ino-chlorophenol. The bathochromic shift of the dibenzanthrone spectrum on substitution of two methoxyl groups in the 16: 17-positions of dibenzanthrone is ascribed to the over-riding tendency of the dibenzanthrone ring system to remain planar and hence force the methoxyl groups also to be coplanar with the ring system.

      The absorption spectra of 3:3′- and 4:4′-dibenzanthronyls have been reported and discussed.

    • Anthraquinone and anthrone series - Part XII. The benzanthrone condensation on 2-chloroanthraquinone

      P N Pandit B D Tilak K Venkataraman

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      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-chloroanthraquinonevia 3-chloro-1-cyanoanthraquinone. There is no evidence of the formation of the unknown 5-chlorobenzanthrone in the product of the benzanthrone condensation on 2-chloroanthraquinone.

    • Anthraquinone and anthrone series - Part XIII. Synthesis of 5-substituted benzanthrones

      S S Malhotra B D Tilak K Venkataraman

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      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.

    • Anthraquinone and anthrone series - Part XIV. 1-Amino-3-chloroanthraquinone

      B S Joshi N Parkash K Venkataraman

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      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.

    • Synthetical experiments in the chromone group - Part XXX. A synthesis of 3:5:8:3′:4′-pentahydroxyflavone and its non-identity with ponderosin

      V Ramanathan K Venkataraman

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      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 ofPonderosa pine bark.

    • Synthetical experiments in the chromone group - Part XXXI. A synthesis of muningin

      S S Karmarkar K H Shah K Venkataraman

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      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.

    • Potential antitubercular compounds - Part III. 7-Aminoflavone

      D S Bapat K Venkataraman

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      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 acetoneO-benzoylation and the Baker-Venkataraman transformation were both effected in one operation. Cyclization of the diketone and reduction gave 7-aminoflavone, which was also prepared from 4-acetamido-2-hydroxyacetophenone by conversion to the corresponding dibenzoylmethane, cyclization and hydrolysis of theN-acetyl group. 7-Amino-3′∶4′-methylenedioxyflavone was synthesized similarly for antitubercular tests, since piperonylic acid has considerable activity.

    • Synthetical experiments in the chromone group - Part XXXII. A synthesis of tectorigenin

      S A Kagal S S Karmarkar K Venkataraman

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      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.

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