Propionic anhydride → 3-(3,4-Difluorophenyl)-2-methylprop-2-enoic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of 2.88 g (0.02 mol) of 3,4-difluorobenzaldehyde, 3.24 g (0.025 mol) of propionic anhydride and 0.92 g (0.02 mol) of sodium propionate under nitrogen is heated at 135° C. with magnetic stirrer for 20 h. The reaction mixture is poured onto 50 ml of water. A solid precipitates, which dissolves when 50 ml of saturated K2CO3 is added with stirring. The basic solution is extracted with ether (2×100 ml). The aqueous phase is then poured into an excess of concentrated HCl and ice. The precipitated white solid is filtered and dried to give 3,4-difluoro-α-methylcinnamic acid, m.p. 122°-125° C.

Provenance & Evidence