One hundred grams of 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether and 25 g of potassium hydroxide were added to 300 ml of 1,3-dimethyl-2-imidazolidinone (to be abbreviated as DMI hereinafter), and the mixture was stirred at 150° C. for hours. The reaction mixture was cooled to room temperature, poured into water, acidified with a concentrated hydrochloric acid, and extracted with benzene. The benzene solution was washed with water, and dried. Benzene was evaporated under reduced pressure. The resulting oily residue was purified by column chromatography (silica gel; eluent: benzene) to give 45.6 g 3-phenoxybenzyl 2-(3-chloro-4-hydroxyphenyl)-2-methylpropyl ether having a melting point of 68° to 69° C.
