an improved oxidation process for preparing 5 - amino - 3 - cyano - 1 -- 4 - trifluoromethylsulphinyl - pyrazole , of formula is described . the process includes admixing 5 - amino - 3 - cyano - 1 -- 4 - trifluoromethylthiopyrazole of formula with dichloroacetic acid and hydrogen peroxide in the presence of a strong acid .