Synthesis and characterization of raffinose fatty acid monoesters under ultrasonic irradiation.

摘要

Raffinose long-chain fatty acid monoesters, which were acylated at the 1 and 6 positions, were synthesized by the acylation of raffinose with aliphatic methyl esters under reduced pressure and ultrasound irradiation. Synthesis yields ranged from 15 to 44 %. The optimum reaction conditions for the acylation reaction include a molar ratio of raffinose to fatty acid methyl ester of 2:1, quantity of anhydrous K₂CO₃ accounted for raffinose of 12 % mol, ultrasonic temperature of 65 degrees C, ultrasonic time of 2 h, and reaction pressure of 10 kPa. The acylation had good monoester selectivity and the raffinose monoesters structural confirmation was obtained by infrared spectroscopy, electrospray ionization mass spectrometry, and nuclear magnetic resonance. These surfactants had a higher percentage of monoesters and the ratio of 1-O-monoester/6-O-monoester is 2.2-2.6. They all had ideal hydrophile-lipophile balance value with similar melting properties.