尿素法合成甲苯二氨基甲酸苯酯反应体系的热力学分析

尿素、甲苯二胺与苯酚反应合成甲苯二氨基甲酸苯酯为一复合反应体系。对该类反应体系进行分析并提出了本反应的4种可能反应路径,采用基团贡献法对4种反应路径中各组分的热力学数据以及各反应的焓变、Gibbs自由能变和平衡常数进行了计算,依据热力学计算结果并结合文献实验数据分析反应路径的可行性及难易程度。结果表明,由尿素、甲苯二胺与苯酚合成甲苯二氨基甲酸苯酯的较好反应路径为:尿素首先与苯酚反应合成氨基甲酸苯酯,然后氨基甲酸苯酯与甲苯二胺反应得到终产物甲苯二氨基甲酸苯酯。计算及分析结果可为该反应的实验研究及过程开发提供理论指导。

Thermodynamic analysis on synthesis of diphenyl toluene dicarbamate via urea route

The synthesis of diphenyl toluene dicarbamate from urea, toluene diamine and phenol is a complex reaction system. On the basis of the analysis for similar reaction system, four possible reaction pathways for synthesizing diphenyl toluene dicarbamate via urea route were proposed. The fundamental thermodynamic data of components in this reaction system were calculated by several methods of group contribution. The reaction enthalpy, Gibbs free energy change and equilibrium constant of all the reactions of the four possible reaction pathways were obtained. According to the results of thermodynamic calculation and experimental data in literature, the feasibility and difficulty of each reaction pathway were discussed. The results show that a better reaction pathway is urea reaction with phenol to give phenyl carbamate and then phenyl carbamate interacting with toluene diamine to form diphenyl toluene dicarbamate. The results from thermodynamic calculation and analysis can provide a theoretical basis for the experimental study and process development of the reaction.