碳酸钾催化碳酸丙烯酯与乙醇酯交换合成碳酸二乙酯  

Potassium Carbonate Catalyzed Synthesis of Diethyl Carbonate by Transesterification of Propylene Carbonate and Ethanol

作　　者：王默[1] 赵新强[1] 安华良[1] 王延吉[1] 

机构地区：[1]河北工业大学化工学院绿色化工与高效节能河北省重点实验室,天津300130

出　　处：《高校化学工程学报》2010年第4期663-669,共7页Journal of Chemical Engineering of Chinese Universities

基　　金：河北省自然科学基金项目(B2007000010);河北省科学技术研究与发展计划项目(072421107D)

摘　　要：采用半连续操作方式,对碳酸钾催化碳酸丙烯酯(PC)和乙醇酯交换合成碳酸二乙酯(DEC)反应进行了研究。碳酸钾对该反应有较好的催化活性,当催化剂用量为反应物质量的1.4%、乙醇与PC摩尔比为6、反应时间为5h、乙醇滴加速度为1.3mL·min-1时,PC转化率达95.2%,DEC选择性为84.9%。结合红外光谱分析结果推测了碳酸钾催化剂上PC与乙醇酯交换合成DEC的反应机理:K2CO3与乙醇反应生成CH3CH2OK和KHCO3,CH3CH2O-作为亲核试剂进攻PC羰基碳原子生成中间产物羟丙基乙基碳酸酯(HPEC),其他CH3CH2O-进一步进攻HPEC的羰基碳原子得到产物DEC,同时伴随着副产物1,2-丙二醇(PG)的生成以及KHCO3重新转化为K2CO3。The reaction mechanism of diethylene carbonate （DEC） synthesis via transesterification of propylene carbonate （PC） with ethanol was studied by a semi-continuous operation over potassium carbonate catalyst.Through the thermodynamical analyses,it was found that the transesterification reaction is an endothermic reaction,therefore elevating the reaction temperature is favorable for the reaction;besides,removing the product DEC out of the reaction system in time can also promote the reaction.Under the suitable reaction conditions,such as the weight percentage of catalyst used 1.4%,molar ratio of ethanol to PC 6：1,reaction time 5 h and the flow rate of ethanol 1.3 mL？min？1,the conversion ratio of PC,the yield of product DEC and the selectivity of DEC are 95.2%,80.8% and 84.9%,respectively.According to the IR analyses,the reaction mechanism of DEC synthesis via transesterification of PC and ethanol was proposed as follows：the K2CO3 reacts with ethanol to form CH3CH2OK and KHCO3;then the nucleophilic CH3CH2O-attacks the carbonyl carbon atom of PC to produce an intermediate,hydroxypropyl ethyl carbonate （HPEC）.The further attacking the carbonyl carbon atom of HPEC by another CH3CH2O-gives the product DEC.Simultaneously,the by-product 1,2-propylene glycol （PG） is formed and the KHCO3 is converted back to K2CO3.

关 键 词：碳酸二乙酯 碳酸丙烯酯 乙醇 酯交换 碳酸钾 

分 类 号：TQ225.52[化学工程—有机化工]