Esterification of Maleic Anhydride with Trimethylpropane

Trimethylolpropane maleates(TMPMs) were prepared by esterification of trimethylolpropane(TMP) with maleic anhydride(MA).The effect of feed ratio,temperature,reaction time and catalyst on the esterification reaction was studied,and the results indicate that the esterification rate of MA could reach more than 99% with n(MA)∶n(TMP) lower than 2.5∶1 under 90 ℃ for 240 min,while the esterification rate of MA could reach more than 99% with n(MA)∶n(TMP)=3∶1 under 90 ℃ for 240 min only when toluene-p-sulfonic acid was used as catalyst which accounted for 0.2% of the total mass of the monomer.Catalyst addition was conducive to the increase of esterification rate of MA,which could reach over 99% without diesterification of MA.The structure and composition of TMPMs were characterized and analyzed by means of NMR,and the average double bond functionality(ADF) of TMPMs were calculated by esterification rate.