An efficient method for synthesis of 2-ethyl hexyl-4-methoxy cinnamate: A raw material for cosmetic industry

Methyl, ethyl and isopropyl esters of 4-methoxy cinnamic acid could be synt hesized by Claisen condensation of anisaldehyde with the respective alkyl a cetate at a temperature of 0 - 5 degrees C using stoichiometric amount of s odium and a few drops of methanol, the latter being used as' an initiator. The yield of the ester of cinnamic acid was about 77%. When the reaction wa s extended to the synthesis of 2-ethylhexyl ester of cinnamic acid, the rea ction rates were rather very poor and it was necessary to carry out the rea ction at the temperature of 28 degrees C which resulted in the extensive hy drolysis of the starting acetate and the product ester. In the case of 2-et hyl hexyl ester, theeefore, it may be desirable to resort to the synthesis of ethyl / methyl ester of the cinnamic acid by Claisen condensation follow ed by transesterification of the ethyl / methyl ester. Thus, transesterific ation of ethyl 4-methoxy cinnamate with excess of 2-ethyl hexanol and p-tol uenesulfonic acid as catalyst at 150 degrees C gave a yield of 93% in 6 h.