碳酸乙烯酯与乙醇酯交换同时合成碳酸二乙酯和乙二醇的反应过程分析  

ANALYSIS OF REACTION PROCESS OF SIMULTANEOUS SYNTHESIS OF DIETHYL CARBONATE AND ETHYLENE GLYCOL VIA TRANSESTERIFICATION BETWEEN ETHYLENE CARBONATE AND ETHANOL

作　　者：何娇 陈雪莹 张发涛 王丽苹 He Jiao;Chen Xueying;Zhang Fatao;Wang Liping(College of Chemistry and Environmental Science, Qujing Normal University, Qujing 655011, Yunan, China)

机构地区：[1]曲靖师范学院化学与环境科学学院,云南曲靖655011

出　　处：《精细石油化工》2020年第4期48-52,共5页Speciality Petrochemicals

基　　金：云南省本科高校转型发展课题(2015BZGB11);国家级大学生创新创业训练计划项目(201810684019);云南省大学生创新创业训练计划项目;曲靖师范学院重点课程(ZDKC2016005)。

摘　　要：采用基团贡献法对碳酸乙烯酯(EC)与乙醇酯交换同时合成碳酸二乙酯(DEC)和乙二醇(EG)反应过程中可能发生反应的焓变、熵变、吉布斯自由能变和平衡常数等进行了计算。结果表明,第一步反应的焓变和吉布斯自由能变在323~373 K之间均为正值,且平衡常数明显较其余各步反应的小,适当升高温度有利于DEC和EG的生成。2-羟乙基乙基碳酸酯(EHC)与乙醇反应的平衡常数明显较EHC歧化反应的大,这说明DEC主要通过EHC与乙醇反应得到。因此,EC与乙醇酯交换同时合成DEC和EG反应的机理可能是乙醇分子上的羟基氧进攻EC分子上的羰基碳,反应生成中间体EHC,EHC再与乙醇反应生成DEC和EG。The enthalpy changes,entropy changes,Gibbs free energy changes and equilibrium constants of each step in the simultaneous synthesis of diethyl carbonate(DEC)and ethylene glycol(EG)via transesterification between EC and ethanol were calculated by group contribution methods.The results show that the enthalpy change and Gibbs free energy change of the first step are positive within the range of 323373 K,and the equilibrium constant is obviously lower than that of the other steps.The proper increase of temperature is beneficial to the formation of DEC and EG.The equilibrium constant of reaction between ethyl 2-hydroxyethyl carbonate(EHC)and ethanol is significantly higher than that of dismutase reaction between EHCs,which indicates that DEC is mainly obtained through the reaction between EHC and ethanol.Therefore,the mechanism of the simultaneous synthesis of DEC and EG via transesterification between EG and ethanol may be that hydroxyl oxygen on ethanol molecule attack carbonyl carbon in EG molecule to form intermediate EHC,and EHC reacts with ethanol to form DEC and EG.

关 键 词：碳酸二乙酯 乙二醇 碳酸乙烯酯 乙醇 酯交换 基团贡献法 

分 类 号：TQ013.1[化学工程]