Method for producing 6-alkyl-4- (pyridin-3-yl-methyleneamino) -4,5-dihydro-1,2,4-triazin-3 (2H) -one

摘要

A process for the preparation of 6-alkyl-4-(pyridin-3-yl-methyleneamino)-4,5-dihydro-1,2,4-triazin-3(2H )-one by the reaction of 4-amino-6-alkyl-3-oxo-2,3,4,5-tetrahydro-1,2,4-triazine with 3-cyanopyridine wherein the reaction is carried out under catalytic hydrogenation conditions in the presence of a Raney-nickel catalyst in an aqueous alcoholic medium, at a temperature between 0 and 70 DEG C, at a pH of between 2 and 7, and in the presence of and a C1-C6-carboxylic acid or a C1-C6-carboxylic acid alkali metal salt or both, whereby the hydrogen pressure is between 0.1 and 10 bar.