Microwave-Assisted Synthesis of Cinnamyl Long Chain Aroma Esters

Cinnamyl long chain aroma esters were prepared by using the conventional and microwave-assisted methods. The esterification reaction of naturally occurring 3-phenyl-prop-2-en-1-ol and different chain lengths acidic and diol reagents was carried out at the temperature of 140 °C under solvent free conditions. As acidic reagents, oxolane-2,5-dione, oxane-2,6-dione, hexanedioic acid and decanedioic acid were applied. Ethane-1,2-diol and 2,2ʹ-[oxybis(2,1-ethandiyloxy)]diethanol were used as diol reagents. The synthesis of high molecular mass cinnamyl esters under conventional method conditions requires a long time to obtain high yields. The studies confirm that by using microwave irradiation, it is possible to reduce the reaction times to only 10–20 min. The structures of prepared esters were confirmed on the basis of FTIR, (1)H-NMR and (13)C-NMR. In addition, the newly obtained cinnamyl long chain esters were tested for their thermal properties. The TG studies proved the high thermal resistance of the obtained esters under inert and oxidative conditions.