1,2,3-thiadiazole-4-carboxylic acid, 5-hydrazino-, ethyl ester InChI=1/C5H8N4O2S/c1-2-11-5(10)3-4(7-6)12-9-8-3/h7H,2,6H2,1H ethyl 5-hydrazino-1,2,3-thiadiazole-4-carboxylate