Synthesis of Diethyl Maleate Catalyzed by Ti(SO4)2/SiO2

[Aims] The highly active and environment-friendly catalyst for the synthesis of diethyl maleate was investigated, and the synthesis conditions of diethyl maleate were optimized. [Methods] Diethyl maleate was synthesized from maleic anhydride and ethyl alcohol by using Ti(SO4)2/SiO2as catalysts. The influencing factor on esterification rate was investigated such as the amount of catalyst, molar ratio of alcohol to acid, catalyst dosage, reaction time, type and amount of water-carrying agent and the situation of the catalyst used in repeated experiments. [Results] The optimal reaction conditions on synthesis of diethyl maleate were obtained: the molar ratio of alcohol to acid is 3.0∶1.0, the dosage of catalyst is 31%(base on the maleic anhydride), water-carrying agent is cyclohexane, reaction time is 2 h. In this condition the yield of the esterification could reach 96.41%, the esterification rate still reached 74.54% when the catalyst was used at fourth times. The purity of the product reached 90.10% by GC-MS. [Conclusions] Ti(SO4)2/SiO2is a type of high efficient and environment-friendly catalyst for the synthesis of diethyl maleate, and the synthetic process is simple with mild reaction conditions, high yield and purity.