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对羟基苯甲酸分别与正庚醇、正辛醇、正十一醇、正十二醇在对甲苯磺酸催化下,以苯为溶剂,直接酯化合成尼泊金庚酯、辛酯、十一酯、十二酯,用正己烷为溶剂重结晶得到最终产品。其最佳的反应条件是:醇与对羟基苯甲酸摩尔比3:1,反应时间为4h,反应温度为130~140℃,对甲苯磺酸与对羟基苯甲酸的摩尔比0.07:1;产率分别为:83.1%、85.4%、90.3%、94.6%。
P-Hydroxybenzoic acid was directly esterified with n-heptanol, n-octanol, n-undecanol and n-dodecanol with p-toluenesulfonic acid and benzene as solvent to synthesize heptylparaben, Monoesters and dodecyl esters were recrystallized from n-hexane to give the final product. The optimum reaction conditions are: the molar ratio of alcohol to p-hydroxybenzoic acid is 3: 1, the reaction time is 4h, the reaction temperature is 130 ~ 140 ℃, the molar ratio of p-toluenesulfonic acid to p-hydroxybenzoic acid is 0.07: 1; Rates were: 83.1%, 85.4%, 90.3%, 94.6%.