Study On O-Xylene Selective Nitration And Catalytic Hydrogenation In Low Pressure

In this thesis, 3,4-xylidine which is an important organic intermediates widely applied in pharmacy, pesticide, and dye industries, has been prepared by selective nitration and catalytic hydrogenatuion in low pressure, using o-xylene as start material. The main content consisted of three sections.In the first section, the synthesis of 3,4-xylidine have been reviewed. Selective nitration of o-xylene and catalytic hydrogenation were also mainly discussed.In the second section, the selective nitration of o-xylene had been studied. The experimental results showed that nitration of o-xylene has good para-position selectivity in the presence of polyphosphoric acid. And the technologic conditions such as concentration of phosphoric acid ,temperature and so on were optimized. Under the selected conditions, the ratio of 4-nitro-o-xylene in the product rised from 45% to about 83%. Some other similar aromatic compounds such as toluene and chlorobenzene are also studied.In the third section, synthesis of 3,4-xylidine was studied byhydrogenation of 4-nitro-o-xylene in nickel catalyst, the conversation of 4-nitro-o-xylene was more than 99.9%. Factors such as concentration of 4-nitro-o-xylene, hydrogen pressure, temperature and solvent were studied and simple dynamics of hydrogenation of 4-nitro-o-xylene in low pressure were discussed.