3-Chloro-2-chloromethyl-4-(4-chlorophenoxy)-1-butene (1) was prepared in 72% yield by electrooxidative double ene-type chlorination of 1-(4-chlorophenoxy)-3-methyl-2-butene. The electrolysis was conducted at room temperature in a two layer solvent system of dichloromethane and water in the presence of acids (HCl, H 2 SO 4, H 3 PO 4, etc). Either 3- chloro-2-methyl-4-(4-chlorophenoxy)-1-butene or 1 was selectively prepared, respectively ...