Method for the preparation of 4-amino-6-tert. butyl-3-methylthio-1,2,4-triazin-5(4H)-one

摘要

The herbicidally active compound 4-amino-6-tert-butyl-3-methylthio-1,2,4-triazin-5- (4H) -one (I) is obtained by firstly using pivaloyl cyanide, (CH3) 3C- CO-CN (II), with a carboxylic anhydride of the general formula R-CO-O-CO-R (III), in which R represents an optionally substituted aliphatic radical having up to 8 carbon atoms or an optionally substituted phenyl radical, in the presence a strong acid and optionally in the presence of a solvent at temperatures between -50 and 150 ° C and the reaction mixture thus obtained is then reacted directly with thiocarbohydrazide (NH2-NH-CS-NH-NH2) (IV) and the 4-amino formed -6-tert-butyl-3-mercapto-1,2,4-triazin-5- (4H) -one (V) is separated off and in a second step this intermediate (V) is methylated in the usual way.