This article discusses the synthesis of allyl-3-cyclohexylpropionate, which includes cinnamic acid, its ester and/or its methylester, hydrogenation and esterification, transesterification, of hydrogenation products. The hydrogenation kinetics of both initial substances using platinum (Pt/C), palladium (Pd/C), and ruthenium on active carbon as catalysts (Ru/C) were studied. Consequently, 3-cyclohexylpropionic acid was esterificated using p-toluensulfonic acid as the catalyst. The reaction equilibrium was shifted with the elimination of the resulting water in a hexane-water azeotrope form (formation, mold). Next, 3-cyclohexylpropionic acid methylester was transesterificated with allylalcohol and catalyzed with carbonate calcium. The reaction equilibrium was shifted with the elimination of the resulting methanol in a cyclohexane-methanol azeotrope form. Based on the previous experiments, a procedure for preparation of allyl-3-cyclohexylpropionate was chosen, which included cinnamic acid methylester hydrogenation and 3-cyclohexylpropionic acid methylester transesterification with allylalcohol.
Allyl-3-cyclohexylpropionate is an important compound for preparation of perfume compositions and taste complexes of the pineapple type. This ester1 cannot be found in nature. It has a strong fruity fragrance and sweet fruity taste resembling pineapple. It is used as a major carrier of a fruity essence in pineapple imitations and interesting modifier in strawberry, raspberry and other imitations.
For the preparation of allyl-3-cyclohexylpropionate, 3-cyclohexylpropionic acid, allylalcohol or allylchloride are usually used as the starting material. One of the less-frequently described preparation techniques of 3-cyclohexylpropionate is the reaction of allylalcohol with the aqueous solution of either the natrium or calcium salt of a pertinent acid in the presence of natrium iodide and Et3N(CH2Ph)Cl as the phase-transfer catalyst. Another preparation technique3 of allyl-3-cyclohexylpropionate is the reaction of 4-vinyl-1-cyclohexene with carbon dioxide in methanol in the presence of (CO)8CO2- pyridine complex, followed with hydrogenation and re-esterification with allylalcohol of the attained methyl-3-cyclohexylpropionate. Literature provides preparation techniques of the mentioned ester initiated with metacrylate3 and benzaldehyde3. The objective of this work was to assess two preparation methods of allyl-3-cyclohexylpropionate (Figure 1 and Figure 2).