Evaluation of esterification of oleic acid and glycerol in the presence of organotin(IV) compounds

Esterification of oleic acid (OA) and glycerol (GLY) is studied in the absence and in the presence of the organotin(IV) catalysts (CAT) dibutyltin dichloride (Bu2SnCl2), butyltin trichloride (BuSnCl3), dibutyltin dilaurate (Bu(2)SnLau(2)), butyl stannoic acid (BuSnO(OH)), and di-n-butyl-oxo-stannane (Bu2SnO). The reactivity order observed at 180 degrees C using a OA/GLY/CAT molar ratio of 1/1/0.01 was BuSnCl3>Bu(2)SnLau(2)>Bu2SnCl2>Bu2SnO>BuSnO(OH), and a k(ap) of -0.6237h(-1) is obtained for BuSnCl3. The estimated activation energy for the conversion reaction of OA at the above molar ratio using BuSnCl3 is 60.9kJmol(-1), whereas it is 71.3kJmol(-1) for the reaction performed without the catalyst. Moreover, the most active catalytic systems are those that act as typical and pure Lewis acids, and the least active systems are those that follow the ligand exchange mechanism, suggesting that GLY and AO are involved in the ligand exchange process and may form less reactive catalytic species.Practical Applications: In order to expand the glycerol utilization, the aim of the present work is to systematically investigate the behavior of organotin(IV) compounds bearing different substituents on the metal center (oxo, carboxyl, chloro, and hydroxy groups) in the esterification of OA and GLY without a solvent for obtaining MAGs, DAGs and TAGs. Best results of esterification of AO+GLY are attained at 180 degrees C using BuSnCl3 as a catalyst, and the k(ap)=-0.6237h(-1) for OA conversion is obtained.