气提法合成二甲基丙烯酸乙二醇酯

以乙二醇和甲基丙烯酸为原料,直接酯化法合成二甲基丙烯酸乙二醇酯,反应过程中通入空气代替带水剂带出反应生成的水。考察了氮气、氩气、二氧化碳与氧气以不同比例混合作为带水气体对反应收率的影响,结果表明,纯氮气、氩气和二氧化碳没有辅助阻聚作用,纯氧气的辅助阻聚作用比混合气体的辅助阻聚作用弱,空气是具有良好辅助阻聚作用的带水剂,可以减少阻聚剂的用量。还考察了反应温度、催化剂用量、醇酸摩尔比、反应时间、空气流量和阻聚剂用量对收率的影响,在催化剂对甲苯磺酸用量为反应物总质量的5%,n(乙二醇)∶n(甲基丙烯酸)=1∶2.4,通入的空气体积流量为0.2L/min,阻聚剂对苯二酚用量为反应物总质量的0.1%,反应温度110℃,反应时间3h的条件下,二甲基丙烯酸乙二醇酯收率达93.5%。

Synthesis of Ethylene Glycol Dimethacrylate by Air Stripping

Ethylene glycol dimethacrylate was synthesized by the direct esterification of ethylene glycol and methacrylic acid.Instead of the water-carrying agent,air was used to remove the water that resulting from the esterification process.The effects of mixture gas of oxygen with nitrogen,argon and carbon dioxide respectively were investigated.The results showed that nitrogen,argon and carbon dioxide have no assisted inhibit ability,and the assisted inhibit ability of the mixture of oxygen with other gases were better than pure oxygen.Air was the optimum water-carrying gas which can reduce the dosage of inhibitor.The effects of dosage of catalyst,ratio of ethylene glycol and methacrylic acid,reaction time,rate of air and dosage of inhibitor on the yield were also investigated.The yield was 93.5% at the optimum conditions:dosage of tosic acid was 5% of the total weight of reactants,n(ethylene glycol)∶n(methacrylic acid)=1∶2.4,volume flow rate of air was 0.2 L/min,dosage of hydroquinone was 0.1% of the total weight of reactants,reacting at 110 ℃ for 3 hours.