• B D Tilak

      Articles written in Proceedings – Section A

    • 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.

    • 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.

    • 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.

    • 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 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.

    • A new synthesis of thiophenes and thiapyrans - Part I. A new synthesis of thionaphthene, its scope and limitations

      B D Tilak

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      Cyclization of phenyl ω-dimethoxyethyl sulphide (I) under different conditions was studied and an optimum yield of 37% of thionaphthene was obtained by treatment with a mixture of phosphorus pentoxide and phosphoric acid under closely defined conditions. Phenyl ω-diethoxyethyl sulphide (II) also gave thionaphthene in 32% yield under similar conditions.

      The new synthesis of thionaphthene, which has been extended to substituted thionaphthenes and to other thiophenes and thiapyrans reported in subsequent communications consists in the cyclization of aryl ω-dimethoxyethyl sulphides Ar [SCH2CH(OMe)2]n. The scope and limitations of the new synthesis are discussed.

    • A new synthesis of thiophenes and thiapyrans - Part II. Monomethylthionaphthenes and monochlorothionaphthenes

      A V Sunthankar B D Tilak

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      5-Methyl-(II) and 6-methyl-thionaphthenes (IV) and the hitherto unknown 7-methyl-(VI), 5-chloro-(IX), 6-chloro-(XI) and 7-chloro-thionaphthenes (XIII) were prepared by the new synthesis. 7-Methylthionaphthene-1-dioxide (VII) was also prepared.

    • A new synthesis of thiophenes and thiapyrans - Part III. Hydroxythionaphthenes and A’lkoxythionaphthenes

      A V Sunthankar B D Tilak

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      5-Methoxythionaphthene (II) and the hitherto unknown 6-methoxy-(IV), 7-methoxy- (VI) and 5-ethoxy-thionaphthenes (VIII) have been prepared by the new synthesis. 6-Methoxy-5-methylthionaphthene (X) was also prepared similarly and gave 6-methoxy-5-methylthionaphthene-1-dioxide (XI) on oxidation. Demethylation of (VI) and (X) gave 7-hydroxythionaphthene (XIII) and 6-hydroxy-5-methylthionaphthene (XIV).

    • A new synthesis of thiophenes and thiapyrans - Part IV. Thiophenes and thiapyrans from naphthalene thiols

      B D Tilak

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      4:5-Benzothionaphthene (II) was obtained by theα-cyclization ofβ-naphthylω-dimethoxyethyl sulphide (I), and the hitherto unknown naphtho-(1′:8′-bc)-thiapyran (IV) by theperi-cyclization ofα-naphthylω-dimethoxyethyl sulphide (III).

      Naphthalene-1:5-dithiol was obtained in 85% yield by an improved method. Condensation of naphthalene-1:5 and 2:6-dithiols with two molecules of bromoacetaldehyde dimethyl acetal gave (VIII) and (XI). The former cyclized in theperi-positions to give “1:6-thiapyrene” (IX) which was orange in colour, and the latter cyclized in theα-positions to give 4:5, 5′:4′-dithionaphthene (XII), an isoster of chrysene which was colourless. Chrysene and (XII) gave similar absorption spectra, which were markedly different from the absorption spectrum of (IX).

    • A new synthesis of thiophenes and thiapyrans - Part V. 6:7-Benzothionaphthene and 9-chloronaphtho-(1′:8′-bc)-thiapyran

      V K Dikshit B D Tilak

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      8-Chloro-1-thionaphthol, prepared fromperi-acid, was condensed with bromoacetaldehyde dimethyl acetal to give 8-chloro-1-naphthylω-dimethoxyethyl sulphide (IV). Ring-closure of (IV) gave 3′-chlorobenzo-(1′:2′, 6:7)-thionaphthene (V), which on dechlorination gave 6:7-benzothionaphthene (II). The cyclization product fromα-naphthylω-dimethoxyethyl sulphide (I) reported in the previous communication being different from (II) is therefore naphtho-(1′:8′-bc)-thiapyran (III).

      9-Chloronaphtho-(1′:8′-bc)-thiapyran (VII) was prepared from Tobias acid in a manner similar to (V), but dechlorination of (VII) to (III) could not be carried out due to the low yields of (VII) in the cyclization of 2-chloro-1-naphthylω-dimethoxyethyl sulphide (VI).

      The literature on the cyclization of certain relatedα-substituted naphthyl, naphthoxy and thionaphthoxy derivatives is discussed.

    • A new synthesis of thiophenes and thiapyrans - Part VI. 7 : 8-benzothiophanthrene

      B D Tilak

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    • Sulphur isosters of carcinogenic hydrocarbons1—Part I

      B D Tilak

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    • 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 X. Some derivatives of benzanthrone and dibenzanthrone

      P N Pandit B D Tilak K Venkataraman

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    • A new synthesis of thiophenes and thiapyrans - Part VII. Bromothionaphthenes and 5-nitrothionaphthene

      K Rabindran A V Sunthankar B D Tilak

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      5-Bromothionaphthene and 7-bromothionaphthene were prepared by the cyclization ofp-bromophenylω-dimethoxyethyl sulphide ando-bromophenylω-dimethoxyethyl sulphide respectively.

      The new synthesis of thionaphthene may also be extended to negatively substituted thionaphthenes as shown by the synthesis of 5-nitrothionaphthene (VI) by the ring-closure ofp-nitrophenylω-dimethoxyethyl sulphide (V).o-Nitrophenylω-dimethoxyethyl sulphide could not be cyclized by the usual method. 5-Aminothionaphthene andp-aminophenylω-dimethoxyethyl sulphide were obtained by the reduction of (VI) and (V) respectively.

    • Thiophenes and thiapyrans - Part VIII. A new synthesis of dibenzothiophene and its derivatives; its scope and limitations

      K Rabindran B D Tilak

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      A new synthesis of dibenzothiophene (I) which has been extended to its substituted derivatives has been developed. It consists in the condensation of thiophenol with 2-bromocyclohexanone to give 2-phenylmercaptocyclohexanone (II), cyclization of (II) with phosphorus pentoxide to 1:2:3:4-tetrahydrodibenzothiophene and selenium dehydrogenation of the latter compound to give (I) (overall yield 52%).

      Starting with suitably substituted thiophenols, 2-methyl-, 3-methyl and 4-methyldibenzothiophenes and 4-methoxydibenzothiophene have been synthesized. The synthesis of 2-methoxydibenzothiophene could not be completed due to the low yield of 2-methoxy-6:7:8:9-tetrahydrodibenzothiophene. Attempts to cyclize 2-(4′-nitrophenylmercapto)cyclohexanone by means of phosphorus pentoxide by the usual method were unsuccessful.

      The scope and limitations of the new synthesis are discussed.

    • Naphthoquinone series — Part I - Brazanquinone vat dyes from 2∶3-dichloro-1∶4-naphthoquinone: Part I constitution of “iso-dinaphthalene oxide”

      B Suryanarayana B D Tilak

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      Brazanquinone vat dyes have been prepared by the condensation of 2∶3-dichloro-1∶4-naphthoquinone (I) with α- and β-naphthols and their bromo derivatives and by the condensation with Naphtol AS. Reaction of 1-bromo-2-naphthol with (I) in pyridine gave a halogenonaphthoquinone together with a halogen-free naphthoquinone which proved to be identical with the reaction product (A) obtained from (I) and β-naphthol in pyridine. The 1-position in β-naphthol is thus involved in the condensation with (I) and (A) is therefore constituted as the furan derivative, 1∶2-benzobrazanquinone (V). Constitution of “iso-dinaphthalene oxide” as dinaphtho-(2′∶3′∶2∶3-) (1″∶2″∶4∶5) furan (VI) (follows from its conversion to (V) by oxidation and conversely by its synthesis from (V) by zinc dust distillation. The condensation product of (I) with Naphtol AS is likewise the furan derivative 1∶2-brazanquinone-4-carboxyanilide (VIII) since it is also formed from 1-bromo-2-hydroxy-3-naphthanilide by loss of bromine.

      Introduction of bromine in (V) and 3∶4-benzobrazanquinone and the introduction of the carboxyanilide group in (V) leads to more substantive dyes. The dyes give yellow and orange yellow shades. Fastness properties of the dyes have been determined.

    • Naphthoquinone series — Part II - Brazanquinone vat dyes from 2∶3-dichloro-1∶4-naphthoquinone: Part II

      V K Dikshit B Suryanarayana B D Tilak

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      Brazanquinone vat dyes have been prepared by the condensation of 2∶3-dichloro-1∶4-naphthoquinone (I) with compounds of the Naphtol AS series. Whereas the introduction of halogens and methoxyl groups in the anilide half of Naphtol AS gives more substantive naphthols, derivatives of 1∶2-benzobrazanquinone-4-carboxyanilide (III) which contain these substituents in the carboxyanilide part do not show higher substantivity than (III). The dyes gave yellow, orange-yellow and brownish yellow shades which are moderately fast to light and had good fastness to severe washing and chlorine.

    • Naphthoquinone series — Part III - Brazanquinone vat dyes from 2∶3-dichloro-1∶4-naphthoquinone: Part III

      B Suryanarayana B D Tilak

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      Naphtols AS-BO, AS-SW, AS-S, AS-LB and AS-GR were condensed with 2∶3-dichloro-1∶4-naphthoquinone (I) with the view to prepare brazanquinone vat dyes of higher substantivity and fastness than 1∶2-benzobrazanquinone-4-carboxyanilide (II). Whereas the above Naphtols are highly substantive, the brazanquinone vat dyes obtained from them were less substantive than (II). The dyes gave yellow to violet shades which had good fastness to light and chlorine and moderate fastness to washing.

    • Sulphur isosters of carcinogenic hydrocarbons - Part II. 6∶12-Dimethylbenzo (1∶2-b, 5∶4-b′) dithionaphthene and thionaphtheno (4∶5∶4′∶5′) thionaphthene

      V V Ghaisas K Rabindran B D Tilak

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      With the view to study the significance of the 9∶10-phenanthrene double bond (“phenanthrene bridge”) in 9∶10-dimethyl-1∶2∶7∶8-dibenzanthracene (II), 6∶12-dimethylebenzo (1∶2b, 5∶4-b′)dithionaphthene (V) was prepared where both the phenanthrene bridges in (II) are removed by isosteric replacement with thiophene rings and themeso-positions are blocked by methyl groups. Compound (V) should prove noncarcinogenic.

      2∶7-Dimethoxyethylmercaptonaphthalene (IX) on cyclization gave thionaphtheno(4∶5∶4′:5′-)thionaphthene (VIII). The constitution (VIII) follows from the favoured α-cyclization in the naphthalene series and the similarity of its absorption spectrum with that of 3∶4-benzphenanthrene.

    • Thiophenes and thiapyrans - Part IX. Studies in the dehydrogenation of 1∶2∶3∶4-tetrahydrodibenzothiophene

      K Rabindran B D Tilak

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      The dehydrogenation of 1∶2∶3∶4-tetrahydrodibenzothiophene (I) was studied by using various dehydrogenating agents in order to prepare dibenzothiophene (II) in optimum yield under mild conditions. Dehydrogenation by means of selenium or palladised carbon gave good yields of (II), but the reaction was carried out at high temperatures (>275°). By employing N-bromosuccinimide, the dehydrogenation could be carried out in a facile manner at lower temperatures (76°). These results are of value in the synthesis of derivatives of (II). Thus, whereas dehydrogenation of the chlorotetrahydrobenzothiafluorene (III) by treatment with selenium gave the benzothiafluorene (IV) by simultaneous dehydrogenation and dechlorination, dehydrogenation with N-bromosuccinimide gave the chlorine-containing benzothiafluorene (V).

    • Thiophenes and thiapyrans - Part X. 1∶2-benzo-9-thiafluorene and 3∶4-benzo-9-thiafluorene

      K Rabindran B D Tilak

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      The hitherto unknown angular benzo-9-thiafluorenes, 1∶2-benzo-9-thiafluorene (II) and 3∶4-benzo-9-thiafluorene (III) have been synthesized. The former was prepared starting from α-thionaphthol and 2-bromocyclohexanone. Condensation of these compounds gave 2-(α-naphthylmercapto) cyclohexanone (IV) which on cyclization and dehydrogenation gave (II). The constitution of (II) was proved by its unambiguous synthesis starting from 8-chloro-1-thionaphthol and 2-bromocyclohexanone. Starting from β-thionaphthol, (III) was prepared by similar steps. The constitution of (III) followed from its non-identity with 2∶3-benzo-9-thiafluorene.

    • 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.

    • 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.

    • Thiophenes and thiapyrans - Part XI. A new route to polycyclic thiophenes

      K Rabindran B D Tilak

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      Polycyclic thiophenes have been prepared starting from aryl thiols and 2-bromo-1-tetralone (1). Condensation of thiophenol with (I) gave 2-(phenylmercapto)-1-tetralone, which on cyclization gave 1:2-dihydro-3:4-benzo-9-thiafluorene. Dehydrogenation of the latter gave 3:4-benzo-9-thiafluorene (overall yield 72%). Starting fromβ-thionaphthol andα-thionaphthol, 3:4:5:6-benzo-9-thiafluorene (V) and 1:2:5:6-dibenzo-9-thiafluorene (VI) were synthesized similarly (overall yield, 78% and 76% respectively).

    • 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.

    • Naphthoquinone series - Part IV. Reaction of 2:3-dichloro-1:4-naphthoquinone with ethyl acetoacetate in presence of sodium ethoxide

      B Suryanarayana B D Tilak

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      The constitution of the garnet-red compound (B) obtained by the reaction of 2:3-dichloro-1:4-naphthoquinone with ethyl acetoacetate in the presence of sodium ethoxide has been reinvestigated. The constitution (VI) assigned by Michel to (B) is not in accord with its colour. The compound is now considered to be 2-methyl-1:3-dicarboethoxy-(1-β)-naphthindene-4:9-quinone (VII). The colour of (B), the molecular weight of its diacetoxy derivative (VIII), the synthesis of (B) from ethyl 3-chloro-1:4-naphthoquinone-2-acetoacetate (III) and the formation of the mono- andbis-hydrazine derivatives (IX and X) confirm the new structure, suggested for (B).

    • Thiophenes and thiapyrans - Part XII. Synthesis of thiophthenes

      V V Ghaisas B D Tilak

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      Thieno(3:2-b)thiophene (I) and thieno(2:3-b)thiophene (II) were prepared starting from 3- and 2-thiophenethiols and bromoacetaldehyde dialkoxy acetals. Condensation of the latter with the thiols gave 3-thienyl 2:2-diethoxyethyl sulphide (IV) and 2-thienyl 2:2-dimethoxyethyl sulphide (V) which on cyclization gave (I) and (II).

      Thieno(3:2-b)thionaphthene (IX) was prepared starting from 3-thiophenethiol and 2-bromocyclohexanone. Condensation of the latter compounds gave 2-(3′-thienylmercapto)cyclohexanone which on cyclization gave 5: 6: 7: 8-tetrahydro-thieno(3: 2-b)thionaphthene (VIII). Dehydrogenation of (VIII) gave (IX). 4: 5: 6: 7-Tetrahydrothieno(2: 3-b)thionaphthene (XI) was prepared similarly starting from 2-thiophenethiol. Attempts to dehydrogenate (XI) to thieno (2:3-b) thionaphthene (XII) were unsuccessful.

      We are deeply indebted to the Socony-Vacuum Oil Co. for the gift of 3-thiophenethiol used in the present and in subsequent work. Our thanks are also due to Dr. T. S. Gore for the microanalyses.

    • Naphthoquinone series - Part V. Reaction of 2 : 3-dichloro-1 : 4-naphthoquinone with β-ketoesters, diethyl malonate, acetyl acetone and acetoacetanilide in pyridine

      B Suryanarayana B D Tilak

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      The condensation of 2 : 3-dichloro-l : 4-naphthoquinore (I) with compounds containing a reactive metnylene group in pyridine was studied. The reaction of (I) with ethyl acetoacetate in pyridine gave l-keto-2-carboethoxy-methylenyl-1: 2-dihydronaphthalene-3-pyridinium-4-oxide (VII). The corstitusion assigned to (VII) is supported by its alternative synthesis from (I) and diethyl malonate or ethyl benzoylacetate in pyridine. Hydrolysis of (VII) gave 1-keto-2-carboxymethylenyl-l: 2-dihydronaphthalene-3-pyridinium-4-oxide which was converted to l-keto-2-carboxyanilidomethylenyl-l : 2-hydronaphthalene-3-pyridinium-4-oxide (IX) and 1-keto-2-methylenyl-l: 2-dihydronaphthalene-3-pyridinium-4-oxide.

      The reaction of acetoacetanilide with (I) in pyridine gave (IX) and 1-keto-2-acetomethylenyl-l : 2-dihydronaphthalene-3-pyridinium-4-oxide. The latter was also synthesized from 2-chloro-3-acetonyl-l : 4-naphthoquinone and acetyl acetone by reaction of these substances with (I) in pyridine.

      A reaction mechanism to account for the formation of the above compounds is suggested.

      We are deeply indebted to the Ministry of Education, Government of India, for the award of a Senior Research Scholarship to one of us (B. S.) and to Dr. T. S. Gore for the microanalyses recorded in the paper.

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