An efficient and expeditious synthesis of phytostanyl esters in a solvent‐free system

Abstract

AbstractEsterification of natural phytostanols with various fatty acids by using Lewis acid‐surfactant combined catalyst was investigated. For synthesis of phytostanol esters of saturated fatty acids, cuprum dodecyl sulfate [Cu(DS)2] was the most desirable catalyst due to its high selectivity, reusability, activity, and less corrosivity, whereas stanol selectivity with other catalysts, such as ZnCl2 and tungstophosphoric acid. The substrate molar ratio of 1.2:1 (lauric acid/phytostanols) was the optimal. For synthesis of phytostanol esters of unsaturated fatty acids, cerium dodecyl sulfate [Ce(DS)3] was better than [Cu(DS)2] which was based on the oxidation of the unsaturated fatty acids during the reaction. The chemical structure of the sitostanyl stearate, sitostanyl oleate, and sitostanyl linoleate were confirmed by FTIR, MS, and NMR, respectively. As a result, the [Cu(DS)2] and [Ce(DS)3] were screened to synthesize phytostanyl esters of fatty acids for commercial production.Practical applications: Phytostanols are important for human health and nutrition. Unfortunately, due to the poor solubility of free stanols (unesterified) in fats and oils, there is a demand for a good way to improve the solubility or bioavailability of phytostanols, such as esterification of phytostanols with fatty acids. This study aims at finding an efficient and expeditious synthesis of phytostanyl esters. At the same time, environmental impact and the oxidation of the unsaturated fatty acids during the reaction should be considered.