Highly efficient synthesis of 4,4-dimethylsterol oleates using acyl chloride method through esterification

Abstract In this study, the 4,4-dimethylsterol oleates were efficiently synthesized through esterification of 4,4-dimethylsterols and oleoyl chloride. The impacts of reaction parameters (the reaction time, temperature, and molar ratio of oleoyl chloride to 4,4-dimethylsterols) on the 4,4-dimethylsterol conversion rate were investigated. The reaction conversion increased with the increasing reaction time, temperature, and the molar ratio of oleoyl chloride to 4,4-dimethylsterols. The highest conversion of 99.27% was obtained with molar ratio of 1.1:1 at 313 K for 60 min. A second-order kinetic model describing acyl chloride esterification featuring high correlation coefficients was established. Arrhenius-Van't Hoff plot suggested activation energy and pre-exponential factor were 15.54 kJ mol−1 and 1.78×103 L mol−1 min−1, respectively. The molecular structure of 4,4-dimethylsterol oleates were finally identified by attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR) and ultra-performance liquid chromatography system coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS).