A novel synthesis of hydroxy-1,2,3-benzothiadiazoles

Abstract

Diazotisation and hydrolysis of 5- and 6-aminobenzothiazoles yield the corresponding hydroxybenzothiazoles or the hydroxy-1,2,3-benzothiadiazoles depending on the ratio of nitrous acid to amine employed in the reaction. Diazotisation of 7-aminobenzothiazole with one equivalent of nitrous acid followed by hydrolysis yields 7-amino-1,2,3-benzothiadiazole, whilst two equivalents of nitrous acid give 7-hydroxy-1,2,3-benzothiadiazole.

Nitration of 1,2,3-benzothiadiazole yields 4-nitro-1,2,3-benzothiadiazole in addition to the reported 5- and 7-nitro-compounds.