A solution of 203 parts of 6-[bromo(4-chlorophenyl)methyl]-1-methyl-1H-benzotriazole monohydrobromide and 170 parts of 1H-imidazole in 1350 parts of methylbenzene was stirred for 28 hours at reflux temperature. The reaction mixture was allowed to cool to 80° C. and then evaporated. The oily residue was dissolved in dichloromethane. The organic layer was washed with a diluted hydrochloric acid solution. The separated aqueous layer was treated with a sodium hydroxide solution and extracted with dichloromethane. The combined dichloromethane layers were washed with water, dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of dichloromethane and methanol (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated. To the residue were added 210 parts of 1,1'-oxybisethane and the whole was allowed to stand over weekend. The solid product was filtered off and dried at 50° C., yielding 48.1 parts (29.7%) of 6-[(4-chlorophenyl)(1H-imidazol-1 -yl)methyl]-1-methyl-1H-benzotriazole; mp. 87.7° C. (compound 63).
