Thiazolecarboxylic acids, acidity decarboxylation

Decarboxylation of 2-thiazolecarboxyIic acids occurs readily (49). 5-carboxylic acids can also be decarboxylated without difficulty (50). but 4-thiazolecarboxylic acids are relatively stable (7. 38). For example,... 

The observed order of decreasing ease of decarboxylation for the three thiazolecarboxylic acids is 2>5>4. 

The 2-thiazolecarboxylic acids are too readily decarboxylated to be converted to acid chlorides 16. 12, 79). 

Claisen ester condensation, 6, 279 Thiazolecarboxylic acid chlorides reactions, 6, 279-280 Thiazolecarboxylic acid hydrazides synthesis, 6, 280 Thiazolecarboxylic acids acidity, 6, 279 decarboxylation, 6, 279 reactions, S, 92 6, 274 Thiazole-2-carboxylic acids decarboxylation, S, 92 Thiazole-4-carboxylic acids stability, S, 92 Thiazole-5-carboxylic acids decarboxylation, S, 92 Thiazole-4,5-dicarboxylic acid, 2-amino-diethyl ester reduction, 6, 279 Thiazole-4,5-dicarboxylic acids diethyl ester saponification, 6, 279 Thiazolediones diazo coupling, 5, 59 Thiazoles, 6, 235-331 ab initio calculations, 6, 236 acidity, S, 49 acylation, 6, 256 alkylation, S, 58, 73 6, 253, 256 analytical uses, 6, 328 antifogging agents... 

The nucleophilic reactivity in neutral medium has been used extensively to prepare various thioethers of thiazole (122). In acidic medium, alkylation may be performed with alcohols (123, 124). An unexpected reaction encountered was the decarboxylation of 2-mercapto-4-methyl-5-thiazolecarboxylic acid (60) when treated with butyl alcohol under acidic conditions (Scheme 27) (123). Reaction between A-4-thiazoline-2-thione... 

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