Synthesis of alkenyl succinic anhydrides from methyl esters of high oleic sunflower oil

摘要

Alkenyl succinic anhydrides (ASA) have been prepared by ene-reaction of high-oleic sunflower oil methyl esters with maleic anhydride in a 50% xylene medium.Response surface methodology (RSM) was used to investigate the influence of two factors:reaction temperature and molar ratio between maleic anhydride (MA) and methyl esters (SME).The studied parameters in 8-h reactions were the methyl oleate conversion,the distillation yield in ASA,and responses allowing the indirect estimation of side reaction products:clarity index and dynamic viscosity.The highest yield in ASA (>70%;clarity indexapprox=10) was reached for a temperature of 240-250degC with a molar ratio of 1.5-1.7.But for an industrial application requiring minimized side products (clarity index >40),the optimal synthesis conditions were:temperature between 220 and 235degC and molar ratio of 1.2-1.35 (yield approx=55%).Such conditions did not provide a medium free of side products,even if xylene decreased their formation.Compared to solvent-free synthesis,conversion was lower with xylene.With solvent,higher temperatures were needed to reach the same yields.Supplementary heating compensated the reagent dissolution effect that slows down the kinetics of the ene-reaction.The influence of reaction time at 220degC with a MA/SME ratio of 1.2 in a 50% xylene medium was studied.A reaction time of 8-10 h provided a good compromise between ASA yield and side products.