Efficient microwave-assisted synthesis of glycerol monodecanoate

Solvent-free microwave-assisted synthesis was carried out to prepare 2,3-dihydroxypropyl decanoate, by esterification of decanoic acid in the presence of two distinct glycerol derivatives, glycidol, and glycerol carbonate, respectively. The process described is based on microwaves heating source with electrical power in the range of 200-400 W, involving stoichiometric proportions of decanoic acid and glycerol derivatives, and using catalytic amounts of TBAI used as organocatalyst. Conversion and selectivity rates of esterification reactions were monitored by H-1 and C-13{H-1} NMR spectroscopy. The predominantly formed ester, 2,3-dihydroxypropyl decanoate was fully characterized by infrared and NMR spectroscopy, mass spectrometry, and elemental analysis. Compared with the classical heating procedures, and whatever the glycerol derivatives used, total conversions were obtained with considerably reduced reaction times. Thus, under 300 W, esterification requires only 1 min exposure from glycidol and 5 min from glycerol carbonate. The use of heating with conventional oil bath conditions needs residence times of more than 1 h (even 24 h in the case of glycerol carbonate). The microwave-assisted synthesis also notably enhances the selectivity in 2,3-dihydroxypropyl decanoate (at 300 W, 90, and 50%, respectively), reinforcing the efficiency and the interest of the method.