Preparation of esters

A process for the preparation of an ester of formula I ##STR2## wherein Ar represents a phenoxy substituted phenyl group and R an alkyl group optionally substituted by halophenyl or alkylphenyl or a cyclopropyl group optionally substituted by alkyl, halogen, isobutenyl, dichlorovinyl or dibromovinyl, which process comprises contacting an aromatic aldehyde of the formula ArC(O)H and a (cyclo)aliphatic acyl halide of the formula RC(O)Hal, in which formulas Ar and R have the same meaning as in the formula I and Hal represents a halogen atom, with water, a water-soluble cyanide, a substantially water-immiscible aprotic solvent and a poly(alkyleneoxy)-derivative containing from 1 to 50 alkyleneoxy units formed by reacting an alkanol containing 8 to 20 carbon atoms with ethylene oxide or propylene oxide as catalyst and recovering the desired ester product from the reaction mixture.