碳酸二甲酯与苯酚酯交换合成碳酸二苯酯的热力学性质及均相催化剂

在298.15K,101.325kPa条件下,液态碳酸二甲酯(DMC)的标准Gibbs自由能和熵分别估算为-472.3kJ*mol-1和245.2J*mol-1*K-1.在298K～523K计算了由DMC和苯酚生成碳酸二苯酯(DPC)和苯甲醚反应的热力学性质(ΔrH0m,ΔrS0m,ΔrG0m和平衡常数).计算出的热力学性质表明,DMC和苯酚酯交换合成DPC反应是吸热的,并且在热力学上是不利的.研究了n-Bu2SnO,Ti(OC4H9)4, AlCl3和ZnCl2四种酯交换法合成DPC反应的催化剂,其中n-Bu2SnO具有最高的催化活性.热力学计算和实验结果均表明,合成DPC反应的最佳温度为453K.当以n-Bu2SnO为催化剂,n(苯酚)∶n(DMC)＝4∶1时,DPC的产率和选择性分别为43.0%和88.7%.

The Thermodynamic Properties and Homogeneous Catalysts for the Synthesis of Diphenyl Carbonate by Transesterification of Dimethyl Carbonate with Phenol

The Gibbs free energy of formation and entropy of liquid dimethyl carbonate(DMC) at 298.15K and 101.325kPa were estimated to be -472.3 kJ*mol-1 and 245.2 J*mol-1*K-1 respectively. The thermodynamic properties (ΔrH0m,ΔrS0m,ΔrG0m and equilibrium constant) of the reactions for the production of diphenyl carbonate(DPC) and anisole between DMC and phenol from 298K to 523K were calculated. These values indicated that the reaction of transesterification of DMC with phenol to DPC was endothermic and thermodynamically unfavorable. n-Bu2SnO, Ti(OC4H9)4, AlCl3 and ZnCl2 were tested to catalyze the synthesis of DPC by transesterification of DMC with phenol. n-Bu2SnO had the highest catalytic activity among them. The optimum temperature was 453K for the synthesis of DPC. When the molar ratio of phenol to dimethyl carbonate was 4∶1, the yield and selectivity of DPC were 43.0% and 88.7% respectively using n-Bu2SnO as a catalyst.