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采用尿素和苯胺在常压下加热反应合成了N,N’-二苯基脲(DPU),考察了不同工艺条件及反应、分离强化手段对DPU产率的影响,初步研究了反应机理.实验结果表明,在反应过程中通入氮气,苯胺与尿素摩尔比为5,180℃反应1.5h,反应后减压蒸发分离,DPU的单程产率(以尿素计)达到99.1%.苯胺既是反应物,又是反应介质,反应后未反应的苯胺可循环利用.该工艺不需加任何催化剂和其他溶剂.对反应机理的初步研究表明,苯基脲为主要的反应中间体.
N, N’-diphenylurea (DPU) was synthesized by the reaction of urea with aniline at atmospheric pressure. The effects of different process conditions and reaction and separation intensification methods on the yield of DPU were investigated. The reaction mechanism was preliminarily studied. The results showed that during the reaction, nitrogen was introduced and the molar ratio of aniline to urea was 5 and the reaction was carried out at 180 ℃ for 1.5h. After the reaction, the product was separated by evaporation under reduced pressure. The yield of DPU (urea) was 99.1% Is the reaction medium, the unreacted aniline can be recycled after the reaction.The catalyst does not need to add any catalyst and other solvents.Preliminary studies on the reaction mechanism show that phenylurea is the main reaction intermediate.