Methane → 6-chloro-1-(3-chloropropyl)-1,3-dihydro-2H-benzimidazol-2-one

To a stirred mixture of 22.6 parts of 6-chloro-1,3-dihydro-1-(3-hydroxypropyl)-2H-benzimidazol-2-one and 300 parts of trichloromethane are added dropwise 32 parts of sulfinyl chloride. Upon completion, stirring is continued for 3 hours at reflux. After stirring with activated charcoal, the reaction mixture is filtered hot over hyflo. The filtrate is evaporated and the residue is dissolved in methylbenzene. The solution is washed a few times with water, dried, filtered and evaporated. The oily residue is triturated in 2,2'-oxybispropane. The solid product is filtered off and dried, yielding 19 parts (77.5%) of 6-chloro-1-(3-chloropropyl)-1,3-dihydro-2H-benzimidazol-2-one; mp. 122° C.