Reactions of Benzyl Chloroacetates with Fluoride Ion

Abstract

Reactions of benzyl mono-, di-, and trichloroacetates with fluoride ion generated from potassium fluoride and 18-crown-6 were carried out at 100°C in sulfolane.
Benzyl chloroacetate gave benzyl fluoroacetate, the halo gen exchange ' product, in a high yield (93%). The reaction of benzyl trichloroacetate proceeded by fluoride ion attack to the carbonyl carbon to afford chloroform and benzyl fluoride [3] in addition to a small amount of benzyl chloride [4] J, and none of halogen-exchange products (CCl_3-nF_nCOOCH₂C₆H₅n=1∼3) were obtained. In the reaction of benzyl dichloroacetate, both the halogen exchange and the attack of fluoride anion to carbonyl carbon were observed, and the reaction products were dichloromethane, [3], [4], benzyl difluoroacetate, benzyl 3, 3, 3-trifluoropropionate, and benzyl 3, 3-dichloroacrylate. The reaction mechanisms were discussed.