PROCESS FOR THE PREPARATION OF 3,6-DISUBSTITUTED 4-AMINO-1,2,4-TRIAZIN-5-ONES

摘要

The herbicidal 3,6-substituted 4-amino-1,2,4-triazin-5-one of the general formula IMAGE (I) wherein R1 and R2 have the meaning given in the description, is obtained in good yields by a new two-stage cyclization reaction if an alpha -ketocarboxylic acid amide of the general formula R1-CO-CO-NHR3 (II) is reacted with a hydrazidine of the general formula IMAGE (III) if appropriate in the presence of a diluent at temperatures between 0 DEG and 150 DEG C., whereby in the first process stage a condensation reaction takes place to give condensation products which still have open chains, and in the second process stage an elimination reaction with ring closure takes place to give the end product of formula (I).