研究了在1-丁基-3-甲基咪唑阳离子与咪唑阴离子搭配的碱性[Bmim]Im离子液体催化作用下,碳酸二甲酯(DMC)与异辛醇(EHOH)通过两步酯交换法制备碳酸二异辛酯(DEHC)的合成工艺。确定了合成DEHC的最佳反应条件为:催化剂用量为原料总质量的2.0%,醇酯摩尔比为4∶1,一步反应温度90℃,反应时间2 h,二步反应温度120℃,反应时间4 h,经减压蒸馏可得到DEHC的收率为66.15%,纯度〉99%。使用红外光谱1、H核磁共振谱对DEHC的结构进行了表征。实验结果表明,[Bmim]Im碱性离子液体可作为均相催化剂催化酯交换反应,在双酯合成工艺中具有潜在的应用价值。
Di-2-ethy hexyl carbonate(DEHC) was prepared by transesterifying dimethyl carbonate(DMC) with 2-ethylhexanol(EHOH) in the presense of [Bmim]Im(paired by 1-butyl-3-methylimidazolium cation and imidazolide anion) as a catalyst.The optimum process condition was as follows: the catalyst amounts was 2.0%,molar ratio of 2-ethylhexanol to DMC was 4∶1,the reaction temperature and time of the 1st step is 90 ℃ and 2 h respectively,the reaction temperature and time of the 2nd step is 120 ℃ and 4 h,in that the yield of DEHC is 66.15%.The gas chromatography shows that the purity of DEHC is above 99%.The structure of DEHC was characterized using FTIR and 1H NMR.Our experiments demonstrated that,by taking [Bmim]Im as catalyst,this technology should be a valuable and broadening routine for similar transesterifying reactions.