Abstract: 5-Alkoxy-1,2,4-triazolo[4,3-c]pyrimidine-3(2H)-thione compounds, such as 5-ethoxy-8-fluoro-1,2,4-triazolo[4,3-c]pyrimidine-3(2H)-thione, were prepared by cyclization of 2-alkoxy-4-hydrazinopyrimidine compounds, such as 2-ethoxy-5-fluoro-4-hydrazinopyrimidine, with carbon disulfide and hydrogen peroxide. The reaction can be carried out in the presence of a trialkylamine, such as triethylamine, in which case a trialkylammonium salt is obtained. The products are useful intermediates in the preparation of 5-alkoxy[1,2,4]triazolo[1,5-c]-pyrimidine-2-sulfonamide herbicides.

Abstract: 2-Chlorosulfonyl-5-alkoxy[1,2,4]triazolo-[1,5-c]pyrimidine compounds, such as 2-chlorosulfonyl-5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidine, that are useful for the preparation of 5-alkoxy[1,2,4]triazolo [1,5-c]pyrimidine-2-sulfonamide herbicides, were prepared in an improved manner from 5-alkoxy[1,2,4]triazolo [1,5-c]pyrimidine-2(3H)-thione compounds, such as 5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidine-2(3H)-thione, by oxidation with hydrogen peroxide to obtain novel 2,2'-dithiobis(5-alkoxy[1,2,4]triazolo[1,5-c]pyrimidine) compounds, such as 2,2'-dithiobis (5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidine), and subsequent chloroxidation of these intermediate compounds.

Abstract: 5-Alkoxy[1,2,4]triazolo[1,5-c]pyrimidine-2 (3H)-thione compounds, such as 5-ethoxy-8-fluoro[1,2,4]triazolo[1,5-c]pyrimidine-2(3H)-thione, were prepared by treatment of a 5-alkoxy-1,2,4-triazolo-[4,3-c]pyrimidine-3(2H)-thione compound, such as 5-ethoxy-8-fluoro-1,2,4-triazolo[4,3-c]pyrimidine-3(2H)-thione, with an alkali metal alkoxide in an alcohol solvent selected so that the 5-alkoxy group, the alkoxide, and the alcohol all have the same alkyl group. The trialkylammonium salts of the 5-alkoxy-1,2,4-triazolo [4,3-c]pyrimidine-3(2H)-thione compounds were converted to 3-hydrocarbylthio-5-alkoxy-1,2,4-triazolo-[4,3-c]pyrimidine compounds by reaction with a hydrocarbyl halide, such as benzyl chloride. The products are useful intermediates in the preparation of 5-alkoxy[1,2,4]triazolo[1,5-c]pyrimidine-2-sulfonamide herbicides.

Abstract: 5-Alkoxy-1,2,4-triazolo[4,3-c]pyrimidine-3(2H)-thione compounds, such as 5-ethoxy-8-fluoro-1,2,4-triazolo[4,3-c]pyrimidine-3(2H)-thione, were prepared by cyclization of 2-alkoxy-4-hydrazinopyrimidine compounds, such as 2-ethoxy-5-fluoro-4-hydrazinopyrimidine, with carbon disulfide and hydrogen peroxide. The reaction can be carried out in the presence of a trialkylamine, such as triethylamine, in which case a trialkylammonium salt is obtained. The products are useful intermediates in the preparation of 5-alkoxy[1,2,4]triazolo[1,5-c]pyrimidine-2-sulfonamide herbicides.