- Oxidation and Eliminative Cyclisation of S-Alkylisodithiobiureas
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Isothiocyanates condense with S-alkylisothiosemicarbazides to yield S-alkylisodithiobiureas.These undergo cyclisation to give 3-amino-5-mercapto-4-substituted-1,2,4-triazoles with the elimination of alkyl mercaptan on heating under neutral conditions, whereas under acidic conditions, by elimination of ammonia 5-alkylmercapto-2-substituted amino-1,3,4-thiadiazoles are formed.Condensation of isothiocyanates with thiosemicarbazides in the presence of alkali affords 1-substituted dithiobiureas.Alkylation of these dithiobiureas with alkyl halides results in the formation of 5-alkylmercapto-2-substituted-amino-1,3,4-thiadiazoles, any intermediateproduct not being isolable.On the other hand, oxidation of 1-substituted dithiobiureas with either hydrogen peroxide or iodine furnishes 2-amino-5-substituted-amino-1,3,4-thiadiazoles.
- Indukumari, P. V.,Joshua, C. P.,Rajan, V. P.
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p. 384 - 387
(2007/10/02)
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