The reaction of substituted benzoic acids, dicarboxylic acids such as phthalic, terephthalic, and isophthalic acids, and the sodium or potassium salts of these acids with equimolar or excess epichlorohydrin in the presence of benzyltrimethylammonium chloride has been studied using various solvents such as toluene, dioxane, monochlorobenzene, and tetrachloroethylene. Use of the free carboxylic acids gave only fair to low yields of glycidyl esters, while sodium or potassium salts of the carboxylic acids gave excellent yields of materials of high oxirane content. The epoxidation of chlorohydrin esters of these acids by the dehydrochlorination was also studied using various dehydrochlorinating reagents such as NaOH, KOH, Na2CO3, and NaAlO2in such solvents as water, dichloromethane, dioxane, and monochlorobenzene at various temperatures. Reaction time, reaction temperature, and water content were found to influence the yield of glycidyl esters. It is suggested that the reaction path involves nucleophilic attack upon the terminal position of the epoxide or epichlorohydrin. The resulting alkoxide then reacts further to give either a glycidyl ester or a chlorine-containing by-product, the predominant course depending upon reaction conditions.