Studies On Selenium-catalyzed Preparation Of Symmetric Diaryl Ureas Via Arylamines

This paper makes a systematic study on the solvent-free synthetic method of the symmetric diarylureas by the selenium-catalyzed oxidative carbonylation of arylamines with CO/oxidant.Ureas are widely used in different fields,which can be used as pesticides,pharmaceutical intermediates,herbicides,pesticides,and fungicides,etc.The traditional synthetic methods of ureas are phosgene synthesis,isocyanate synthesis and transition metal catalytic method,etc.The most disadvantage of phosgene method is its hypertoxicity,furthermore,the reaction produces chloride which is corrosive to equipments.Amines can be catalyzed synthesis of ureas by transition metal Pd,Ru and Rh,but the expensive catalysts hinder the industrialization of the reaction.Solvent-free synthetic methods not only save organic solvent and reduce the energy consumption but also avoid the harm to the body,which comply with the concept of green chemistry.This thesis is divided into four parts:The first chapter is literature review on the application of ureas in industrial and the preparation methods of them.The second chapter is the solvent-free synthetic method of the diphenylurea by the selenium-catalyzed oxidative carbonylation of aniline with CO/nitrobenzene.The various influential factors on the reaction are investigated.The third chapter is the solvent-free synthetic method of the diphenylurea by the selenium-catalyzed oxidative carbonylation of aniline with CO/air or CO/oxygen gas.The various influential factors on the reaction are investigated.The fourth chapter is the solvent-free synthetic method of the symmetric diaryl ureas by the selenium-catalyzed oxidative carbonylation of arylamines with CO/air.The reaction results are discussed.The fifth chapter is the conclusion of the work we has done.