Mercaptothiazole Derivatives

Reaction witii Salts and Esters of Ditiiiocarbamic Add 2 Mercaptothiazole Derivatives and 2-Thiazolyl Sulfides 

Initiated by Miolati in 1893 (27), taken up later by Levi (82), and successively by many other authors, the reaction of ammonium dithiocar-bamate (162) with a-halocarbonyl compounds gives 2-mercaptothiazole derivatives with yields varying greatly according to experimental conditions (Table 11-25). 

Similar to their 2-hydroxy analogs, these compounds exhibit properties (cf. Chapter VII) that are characteristic of each of the two possible tautomeric forms the thiol (163a) and the thione or 2-thioxo-A-4-thiazoline (163b). 

2-Mercaptothiazole (163a), Rj =R2 = H, is prepared from chloroacetal-dehyde or a-,/3-dihalogenOethers (268, 296, 521, 597). 

The results initially obtained were due to the formation in both aqueous and alcoholic solution of resinous by-products. This formation results from the decomposition of the ammonium dithiocarbamate, or from the self-condensation of chloroacetaldehyde or the formation of intermediate products. 

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TABI.R n-25. 2-MERCAPTOTHIAZOLE DERIVATIVES FROM AMMONIUM DITHIOCARBAMATE AND o-HALOCARBONYL COMPOUNDS (163s)... 

Mercaptothiazoles with heterocyclic substituents in the 4-position have also been prepared (292, 508, 602). For example, N-alkyl-2-benzimidazolyl chloromethylketones (169) give the corresponding 2-mercaptothiazole derivatives (170) with R, = H, Me, CHjPh, Ac, COPh and R2==H, Me, 5,6-dichloro (Scheme 86) (602). 

Uses, aminothiazoles derivatives, 132-172 hydroxythiazole derivatives, 438-442 mercaptothiazole derivatives, 438-442 UV spectra, 21 of alkylaminothiazoles. 38 and amino-imino equilibrium, 19, 20 and charge transfer, 21 of iminothiazolines, 38 and PPP calculations, 21 and potentiometric measurements, 21 representative data, 22 of Schiff bases, 41 and solvent effects, 21 and substituent effects, 22 of sulfathiazoles, 20 -of sulfonamidothiazoles, 116 of A-2-thiazoline-4-one, 422 pKa determination, 423 of A-4-thiazoline-2-one, in relation with protomerism, 387 representative data, 389 of A-4-thiazoline-2-thiones, 380. 381 in relation with protomerism. 378 of thiazolylcarbamates, 97 of thiazolyl-2-oxides, 409 of thiazolyl-4-oxides, 426 of 2-thiazolylthioethers, 404 of thiazolylthioureas, 94, 96 of thiazolylureas, 93... 

First discovered by Miolati in 1893 (1893G(23)437), the reaction of ammonium dithiocarba-mate with a-halocarbonyl compounds gives 2-mercaptothiazole derivatives, usually in good yields. These compounds have found wide use as accelerators in the vulcanization of rubber (Scheme 178). 

MERCAPTOTHIAZOLE DERIVATIVES FROM a-TH30CYANAT0KET0NES AND LABILE SULFUR"... 

This set of compounds is the most thoroughly studied among derivatives of 2-aminothiazole, thanks to the Beyer group. Heterocychzation methods are most commonly used for their preparation (see Chapter II and Refs. 37, 341, and 513-520). Reaction of 2-diazothiazoles (277) with organometallics provides another synthetic method (Scheme 1711 (521). 2-Hydrazinothiazoles may also be obtained by the action of hydrazine on 2-bromothiazoles (388) or on 2-mercaptothiazoles (522). 

Mercaptothiazoles. Hydroxythiazoles and their Derivatives II. 4- AND 5-SUBSHTUTED THIAZOLES... 

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