Patent ID: 6852857

Claim:
A method of preparing a 4-amino-3-alkylthio-1,2,4-triazine-5-one of the formula (I): wherein R represents C 3-C 8 -alkyl, cycloalkyl having 5-10 ring carbon atoms, unsubstituted or C 1 -C 4 -alkyl-, C 1 -C 4 -alkoxy-, chloro-, or nitro-substituted phenyl, unsubstituted or chloro-substituted phenylalkyl having 1-4 carbons atoms in the alkyl moiety, chlorophenylalkyl having 1-4 carbons atoms in the alkyl moiety, phenylalkenyl having 2-4 carbon atoms in the alkenyl moiety, phenylalkylmercaptoalkyl having 1-4 carbon atoms in the alkylmercapto moiety and 1-4 carbon atoms in the alkyl moiety, furyl, furfuryl, pyranyl, or pyridylmethyl, R 1 and R 2 independently represent hydrogen, C 1 -C 4 -alkyl, C 2 -C 4 -hydroxytrichloro-alkyl, or C 2 -C 5 -alkanoyl, and R 3 represents C 1 -C 18 -alkyl, comprising: (a) reacting in the presence of a base a 4-amino-3-mercapto-1,2,4-triazin-5-one of the formula (II): wherein R, R 1 and R 2 are as defined above for formula (I), with an alkylating agent of the formula R 3 —X, wherein R 3 is as defined above for formula (I), and X represents halide, sulfonate, mono- or dialkyl sulfate, trialkyl phosphate, or dialkyl carbonate; under one or more reaction conditions consisting of (i) including one or more inorganic sulfites and/or inorganic bisulfites, (ii) carrying out a pre-reaction inert gas purge, (iii) applying an alternating inert gas blanket and vacuum before adding the alkylating agent, or (iv) a combination thereof, and (b) collecting the reaction product.