Oxidative hydrolysis of heteroaromatic thiones

A process for preparing a triazolinone of the formula:

• wherein
• R1 represents alkyl having 1 to 6 carbon atoms which is optionally substituted by halogen, cyano or C1-C4 alkoxy, or represents cycloalkyl having 3 to 6 carbon atoms which is optionally substituted by halogen, cyano or C1-C4-alkyl, and
• R2 represents amino, or a radical selected from the group consisting of alkyl, alkenyl, alkinyl, alkoxy, alkylamino or dialkylamino, each or which has up to 6 carbon atoms in the alkyl, alkenyl or alkinyl groups and each of which is optionally substituted by halogen, cyano or C1-C4-alkoxy, or represents a radical selected from the group consisting of C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C2-alkyl or phenyl, each of which is optionally substituted by halogen, cyano, C1-C4-alkyl, C1-C4-alkoxy or C1-C4-alkoxycarbonyl,
• comprising the steps of mixing a triazolinethione of the formula
• wherein R1 and R2 are as defined above in this claim 1,
• with an oxidant at a temperature range of from about 60° C. to about 100° C. in the presence of a base;
• and
• reacting the mixture of said triazolinethione, said oxidant and said base for a time of from about 1 hour to about 6 hours, at a molar ratio of triazolinethione to oxidant to base of from about 1:5:4 to about 1:20:10,
• wherein said mixture of said triazolinethione, said oxidant and said base has a basic pH in the range of about 10 to 14 and wherein said triazolinone is formed without changing said mixture to an acidic pH.