The effect of the nature of phase transfer catalysts and surfactants on the monoalkylation of malonic ester with allyl chloride in the organic phase-40% potassium chloride aqueous solution and organic phase-solid alkali heterophasic systems. The mechanism of the action of phase transfer catalysts was suggested. It was found that the catalytic activity and performance of the systems depended on the nature of the catalysts used and changed in the following order: azacrown ether > crown ether > tetraalkylammonium salts greater than or equal to linear polyesters > sodium alkanoates.