Benzothiazoles. III

Mizuno, Yoshihisa; Adachi, Kikuo

doi:10.1248/yakushi1947.72.6_739

Cited by 6 publications

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“…Discordant m.p. were reported however; 96.5" [5] and 82-83" [6]. Mizuno and Adachi [7] arrived at 6 by still an alternative synthesis, starting from 2-methyl-6-acetylaminobenzothiazole (Chart V).…”

Section: Chart 11mentioning

confidence: 99%

“…The way we succeeded is presented in Chart VI. ; 120" [6]). The slight disparity between the melting points of our product and those reported in the literature may be neglected, and the dearnination -6…”

Section: Chart 11mentioning

confidence: 99%

“…We made however evident that contaiiiination by a chloro compound occurred, when reducing the nitro group of 6 with tin and hydrochloric acid, according to Sych [5] and Mizuno and Adachi [6]. It was observed that catalytic hydrogenation is a far more convenient method affording pure 2-methyl-7-aminobenzothiazole with m.p.…”

Section: H2nmentioning

confidence: 99%

“…req. : N YO,14.4; S %, 16.5; %, 23,7; found: N YO, 14.4; S %, 16.5; -NO, %, 23.6.Reduction of 2-methyl-7-nirrobenzorhiazole a) With tin-hydrochloric acid 5.5 g of 2-methyl-7-nitrobenzothiazole were reduced according to[6], yielding 1.3 g of a product m.p. *120".…”

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The Isomeric Sulfo‐2‐Methylbenzothiazoles and their Use in the Synthesis of Sensitising Polymethine Dyes

Libeer

Depoorter

Nys

1971

Bulletin des Soc Chimique

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Les 4-, 5-, 6-et 7-amino-2-metliylbe1izothiazoles (1) furent transformes en sulfochlorures correspondants 2. Par hydrolyse ceux-ci fournissent les acides sulfoniques 3 et par arnmonolyse les sulfonamides 4 (SchCma I). Un mode de preparation d u 2-m6thyl-7-nitrobenzothiazole ne laissant plus aucun doute quant a la structure du produit obtenu fut elabore (Schema VI). Enfin, les auteurs decrivent la synthbse d e colorants polymethiniques en partant des bases mentionntes et de plusieurs d e leurs derives et Btudient I'effet des substituants sur les proprietes optiques.The isomeric 4-, 5-, 6-and 7-amino-2-metliylbenzothiazoles (1) were converted into the corresponding sulfochlorides 2, which afforded the sulfonic acids 3 on hydrolysis and the sulfonamides 4 on ammonolysis (Chart I). An unequivocal synthesis of 2-methyl-7-nitrobenzothiazole has been elaborated (Chart VI). The heterocyclic bases mentioned and some derivatives were used in the synthesis of spectral sensitizing dyes. The influence of the substituents on the spectral properties of the dyes is investigated.Carbocyanines containing a benzothiazole nucleus substituted a t the 6-position with a sulfo or a sulfamyl group have been reported by Kiprianov and Ushenko [2].The benzothiazoles required as intermediates were obtained by chlorosulfonating 2-methylbenzothiazole and treating the sulfochloride 2 with water or ammonia (Chart 11). On repeating their experiments we obtained in fact a sulfochloride with the m.p. (68") reported. However, in contradiction with the statements of Kiprianov and Ushenko, this product appeared to be not homogeneous, since repeated recrystallisations from hexane raised the m.p. up to 103". Furthermore, conversion of the sulfochloride with m.p. 68" with ammonia resulted in a mixture of sulfonamides (m.p. 184", lit.[2]: I84-185"), which we were able to separate into three isomers with m.p. 214", 245" and 228" respectively. The isomer with m.p. 214" proved to be identical with the sulfonarnide obtained in the sanie way, but starting from the sulfochloride of m.p. 103".These results clearly indicate that the 2-methyl-6-chlorosulfonyl-(2c), 6-sulfo-(3c) and 6-sulfamylbenzothiazole (4c) obtained by Kiprianov and Ushenko were not free from isomers; moreover, the problem remains of determining the position of the substituents in the various isomers.In the course of an investigation of sensitising dyes bearing sulfonamido groups on different positions, we attempted to achieve the synthesis of pure 2, 3 and 4 in a * The contents ofthis paper are the subject of patent applications

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Section: Chart 11mentioning

confidence: 99%

Section: Chart 11mentioning

confidence: 99%

Section: H2nmentioning

confidence: 99%

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The Isomeric Sulfo‐2‐Methylbenzothiazoles and their Use in the Synthesis of Sensitising Polymethine Dyes

Libeer

Depoorter

Nys

1971

Bulletin des Soc Chimique

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“…Starting, 6-nitrobenzothiazole (1) was prepared according to the literature procedure by nitration of benzothiazole with fuming nitric acid. 15 The reduction of 6-nitrobenzothiazole (1) was improved by using ultrasound. An attempt at reductive methylation of NH 2 group with a 10-fold excess of formaldehyde and NaBH 4 16 led to an inseparable mixture of 3 and the major product 5 (Scheme 2).…”

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Preparation of Novel Push-Pull Benzothiazole Derivatives with Reverse Polarity: Compounds with Potential Non-Linear Optic Application

Hrobárik¹,

Sigmundová²,

Zahradnı́k³

2004

Synthesis

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P u s h -P u l l B e n z o t h i a z o l e D e r i v a t i v e s w i t h R e v e r s e P o l a r i t y Abstract: The hitherto unknown 6-dimethylaminobenzothiazole-2-carbaldehyde was prepared as a starting compound for the synthesis of novel push-pull benzothiazole derivatives with reverse polarity. These compounds are substituted at the 2-position by strong electron-acceptor groups and at the 6-position by NMe 2 as strong electron-donor. The new method for synthesis of 6-dimethylaminobenzothiazole involved the successful use of sonochemical reductive methylation. Expected non-linear optical properties of target molecules were studied by EFISH method.

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Notiz zur Synthese von Alkyl‐, Cycloalkyl‐ und Aryl‐(4‐aminophenyl)‐sulfonen

Courtin

1983

Helvetica Chimica Acta

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Syntheses of Some Alkyl‐, Cycloalkyl‐ and Aryl‐(4‐aminophenyl)‐sulfones Syntheses of (4‐aminophenyl)‐alkyl, ‐cycloalkyl and ‐aryl sulfones 2 were achieved both by alkylation of 4‐(acetylamino)‐benzenesulfinic acid (7) to the corresponding acetanilides 9 followed by hydrolysis and by oxidation of the appropriate (4‐nitrophenyl)‐sulfides 11 to (4‐nitrophenyl)‐sulfones 1 with subsequent Béchamp reduction.

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Benzothiazoles. III

Cited by 6 publications

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The Isomeric Sulfo‐2‐Methylbenzothiazoles and their Use in the Synthesis of Sensitising Polymethine Dyes

The Isomeric Sulfo‐2‐Methylbenzothiazoles and their Use in the Synthesis of Sensitising Polymethine Dyes

Preparation of Novel Push-Pull Benzothiazole Derivatives with Reverse Polarity: Compounds with Potential Non-Linear Optic Application

Notiz zur Synthese von Alkyl‐, Cycloalkyl‐ und Aryl‐(4‐aminophenyl)‐sulfonen

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