Abstract: A novel green process for the synthesis of 1,3-diphenyl urea(DPU) by reaction of aniline with carbon dioxide was studied，and the emphasis was put on the investigation of the catalytic performance of Lewis acidic ionic liquids. Firstly, the effects of a series of alkaline or Lewis acid catalysts and solvents on the synthesis of DPU were investigated, and it was found that AlCl₃/acetonitrile system showed excellent catalytic performance. Then the influence of the kind of cation and anion in ionic liquids, initial pressure of CO₂, reaction time,reaction temperature,and catalyst dosage was discussed in the presence of chloroaluminate ionic liquids as both Lewis acid catalyst and solvent. Under the reaction conditions of ［Bmim］Cl-AlCl₃ as both the catalyst and solvent,initial pressure of CO₂ of 1 MPa,reaction time of 7 h,reaction temperature of 160℃,and mass ratio of AlCl₃ to aniline of 1∶1,the conversion of aniline was 18.1%,and the yield and selectivity to DPU were 17.9% and 98.9%,respectively. Additionally, a plausible catalytic reaction mechanism was also proposed.

Key words: aniline, CO₂;1,3-diphenyl urea, Lewis acid ionic liquid

摘要： 以苯胺和二氧化碳为原料催化合成二苯基脲是一条绿色工艺路线，重点对Lewis酸类离子液体催化该反应性能进行了研究。考察了一系列碱性和Lewis酸性催化剂的催化性能，以及溶剂对该反应的影响,结果表明,以无水AlCl₃为催化剂和乙腈为溶剂组成的反应体系效果较好。以氯铝酸类离子液体为催化剂兼溶剂，考察了离子液体阴阳离子、CO₂初始压力、反应时间、反应温度以及催化剂用量等因素对二苯基脲合成反应的影响。结果表明,以［Bmim］Cl-AlCl₃离子液体为催化剂兼溶剂，在CO₂初始压力为1 MPa、反应时间为7 h、反应温度为160℃、AlCl₃/苯胺质量比为1∶1的条件下，苯胺的转化率、二苯基脲的收率及选择性分别为18.1%、17.9%和98.9%。此外，提出了［Bmim］Cl-AlCl₃离子液体催化苯胺和二氧化碳的反应机理。

关键词: 苯胺, CO₂, 二苯基脲, Lewis酸性离子液体