Patent ID: 8629287

Claim:
A process for the sulfinylation of 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-1H-pyrazole-3-carbonitrile (II), consisting essentially of reacting the compound with a sulfinylating agent S in the presence of at least one amine acid complex wherein the amine(s) are cyclic secondary amines selected from the group consisting of piperidine, pyrrolidine, and morpholine, and the acid(s) are selected from the group consisting of p-toluenesulfonic acid, benzenesulfonic acid, and xylene sulfonic acid, and a halogenating agent selected from the group consisting of thionylchloride and phosphoroxychloride, wherein said sulfinylating agent S is selected from the group consisting of CF 3 S(O)Cl, CF 3 S(O)OH, [CF 3 S(O)] 2 O CF 3 S(O)ONa, CF 3 S(O)OK, and mixtures thereof wherein fipronil is obtained.