Studies On Selenium-catalyzed Reduction Of Aromatic Nitro Compounds To Aromatic Amines

New methods of preparing important fine chemical materials, aromatic amines, from aromatic nitro compounds by use of carbon monoxide as reductant are paid ever increasing attention. The key is to develop new catalytic systems that have higher effectiveness and selectivity.Further development and innovation were made to the original catalytic system reducing nitro aromatics to amines by selenium/carbon monoxide/water/ triethylamine in this thesis, which brings into being new catalytic systems with high efficiency, easy separation of product and facile recycling of catalyst.It is observed that the generation of symmetric diarylureas is the main by-reaction while the ureas can be hydrolyzed into amines, so the hydrolysis reaction of diphenylurea was investigated. The results show that the increase of temperature and the extension of reaction time are favorable for the hydrolysis. And also, the hydrolysis of diphenylurea can proceed without any base, but the addition of base can enhance the hydrolysis and some commonly used inorganic bases are superior to tri-ethylamine.On the basis of foregoing study, Inorganic bases as co-catalyst being introduced into the system for the first time, and further more, no any assistant base being added, the reaction of reducing nitrobenzene to aniline was studied, good results was obtained. Under optimized reaction condition, aniline can be produced almost quantitatively. The new reducing systems have the merits of the easy separation ofThe new catalytic systems were used to reduce substituted nitrobenzenes and good results were obtained. For some nitrobenzenes substituted by halogen, carbonyl and cyano groups, the singly selective reduction of nitro was fulfilled, and corresponding aromatic amines were acquired with high yield, which may offer a new, highly efficient and selective, versatile, environmentally benign and low cost synthetic method for the preparation of kinds of aromatic amines.The reduction mechanism of new catalytic systems was discussed with respect to previous related work, and the possible course of nitro group reduction in the new reaction systems was postulated initially.