【作者】 张小艳；

【导师】 李光兴；

【作者基本信息】 华中科技大学 ， 有机化学， 2006， 硕士

【摘要】 碳酸二苯酯(DPC)是一种重要的有机碳酸酯,具有重要而广泛的用途,已引起了国内外的极大关注。在DPC的合成方法中,以苯酚与碳酸二甲酯(DMC)为原料的酯交换法,由于使用的原料无毒、无污染,转化率较高,是目前最佳的合成碳酸二苯酯的方法。要实现其工业化生产,不仅仅要求反应有较高的转化率,更重要的是最终产物的纯度与收率,所以本文对酯交换合成碳酸二苯酯产物的分离提纯做了相关研究。本文首先对釜液的组成进行了分析,其组成为:碳酸二甲酯、苯甲醚(AN)、苯酚(PhOH)、甲基苯基碳酸酯(MPC)和碳酸二苯酯。根据对釜液中各个组分的物理性质的分析及实验,提出分离纯化的方案:先减压蒸馏除去大部分低沸点杂质,然后对DPC的粗产品进行结晶与重结晶提纯。然后采用减压蒸馏和减压精馏的方法对釜液中各组分的分离进行了研究。结果显示釜液中各组分在相应的压力及温度下可有效分离。系统压力为20mmHg时,所得馏分中苯酚的含量达到94.63 %;10～5mmHg时, MPC从釜液中蒸馏出来;最后剩下DPC含量为93.5 %的粗产品。经过乙醇重结晶得DPC,收率为64.5 %。整个实验耗时短,节约能源。使用减压精馏装置,系统压力为20～17 mmHg时,所得馏分中苯酚的含量达到了99 %,相较于减压蒸馏有更好的分离效果。最后对DPC重结晶溶剂的选择进行了研究。结果表明,乙醇是重结晶纯化DPC的适宜溶剂,DPC在乙醇中溶解度在5.0～15.0℃的区间内变化缓慢,重结晶冷却终止温度在15.0℃左右,DPC的收率高于89.0 %。通过对重结晶溶剂的进一步研究,发现采用水-乙醇的混合溶剂作为重结晶溶剂时,可以明显提高DPC的收率。水的质量百分含量在25.0 %～35.0 %范围内时, DPC的收率大于93.0 %,纯度高于99.6%。本文确定了酯交换反应合成DPC的产物分离方案,对DPC的工业生产有重要的指导意义。更多还原

【Abstract】 Diphenylcarbonate(DPC) is an important carbonic ester that has caused the great interest among researchers for its a number of applications. In synthesis paths for DPC, the transesterification of dimethyl carbonate(DMC) with phenol is thought to be the best one due to the use of nontoxic feedstock, no hazard to environment, and high conversion. Not only the high conversion of DPC, but more importantly, the yield of DPC is the key in industrialized operation. Therefor, related research of separation and purification of products in transesterification of DMC and phenol is important and is stdied in this work.According to the result of analyzing by GC-MS, the products of transesterification of DMC and phenol consist of dimethyl carbonate(DMC)、anisole(AN)、phenol(PhOH)、methyl phenyl carbonate(MPC) and DPC. We propound a scheme according to the physical characters and experiments of these components. Most of impurities with low boiling point could be separated from filfrate by distillation under reduced pressure in the first time, then by means of recrystallization in hot ethanol to get pure DPC.The separation of each component is studied by distillation under reduced pressure. The experiments reveal that it can be separated effectively in the certain pressure and temperature. When the pressure of system is 20 mmHg, the contant of PhOH in the distillate is 94.63 %, while the pressure is 10– 5 mmHg, MPC is separated. The contant of DPC in the crude is 93.6 %. The yield is 64.5 % after recrystallization in ethanol. It saves much time and energy. When the pressure of system is 20-17 mmHg, the contant of PhOH in the distillate is 99 % by using rectifying equipment. It is better than the former. Finally, selection solvents for the recrystallization of diphenyl carbonate has been studied. It was found that ethanol was the optimal solvent, the solubility of diphenyl carbonate (DPC) in ethanol changed slowly in the recrystallization temperature range between 5.0℃and 15.0℃. The yield of DPC was as high as 89.0 % at the recrystallization temperature of 15.0℃. It was also found that the yield of DPC could be obviously improved in the case of mixed solvents of water and ethanol used as the recrystallization solvent. The yield of DPC was higher than 93.0 % and the purity of product was 99.6 % when the content of water varied between 25.0 % and 35.0 %.The method of separation and purification of products in transesterification of DMC and phenol in this dissertation will be usefull for the industrialized operation of DPC.更多还原