Oxidation and reduction of some derivatives of benzo-2,1,3-thiadiazole

In the reduction of 4-hydroxy-7-phenylazobenzo-2,1,3-thiadiazole and of 4-hydroxy-7-nitro-benzo-2,1, 3-thiadiazole with sodium hydrosulfite, 7-amino-4-hydroxybenzo-2,1,3-thiadiazole is obtained. The reduction of 4-hydroxybenzo-2,1,3-thiadiazole leads to 2,3-diaminophenol which forms 5-hydroxyquinoxaline with the bisulfite derivative of glyoxal. The oxidation of 4-hydroxy- and 4-aminobenzo-2,1,3-thiadiazoles with potassium dichromate in an acid medium has yielded 4,7-dioxo-4,7-dihydrobenzo-2,1,3-thiadiazole, which has been converted into 4,7-dihydroxybenzo-2,1,3-thiadiazole and 4,7-di(hydroxyimino)-4,7-dihydrobenzo-2,1,3-thiadiazole.Translated from Khimiya Geterotsikliches-kikh Soedinenii, No. 7, pp. 926–929, July, 1973.