【摘要】 采用Benson和Joback基团贡献法对吗啉与碳酸二甲酯反应体系进行了热力学分析,计算了反应体系的焓变、熵变、吉布斯自由能变及反应平衡常数,讨论了温度对吗啉与碳酸二甲酯的甲基化和甲氧羰基化反应的影响。计算结果表明,在373.15～473.15 K范围内,吗啉与碳酸二甲酯的甲基化和甲氧羰基化反应为放热反应,且反应为自发过程,反应平衡常数随温度的升高而减小;与甲氧羰基化反应相比,甲基化反应是热力学上占优势的反应,反应的平衡常数很大,反应进行得较完全;在实验温度范围内,升高温度有利于提高甲基化反应的选择性。更多还原

【Abstract】 The enthalpy changes,entropy changes,Gibbs free energy changes and equilibrium constants in the reaction of dimethyl carbonate with morpholine to N-methyl morpholine were calculated by means of Benson and Joback group contribution methods.The effects of the reaction temperature on both methylation and methoxy-carbonylation reactions of dimethyl carbonate with morpholine were discussed.The results showed that both the methylation and the methoxy-carbonylation reactions were exothermal,and were spontaneous processes because of the negative free energy change in the temperature range of 373.15-453.15 K.The reaction equilibrium constant decreased with rise of the reaction temperature.Compared with the methoxy-carbonylation reaction,the methylation reaction of dimethyl carbonate with morpholine was in thermodynamic control.The reaction equilibrium constant of the methylation was larger than that of the methoxy-carbonylation.The selectivity to the methylation could be improved by raising temperature.更多还原