Synthesis Of2-Methyl-4-Methoxyaniline From O-Nitrotoluene Using Acidic Ionic Liquid And PT/C As Catalyst System

2-Methyl-4-methoxyaniline (MMA) is an important pharmaceutical and chemical intermediate. It can be synthesized from o-nitrotoluene by hydrogenation and Bamberger rearrangement. Generally, this reaction is carried out using sulfuric acid as catalyst for the rearrangement, which suffers from environmental pollution and equipment corrosion. In recent years, ionic liquids have been successfully applied to many organic synthesis reactions as new green solvents and catalysts, because they have the characters of non-volatile of solid acid, the mobility of inorganic liquid acid and the feasibility of structural and functional tunability. In this thesis, six acidic ionic liquids [Hmim]HSO4,[(C2H5)3NH]HSO4,[HSO3-pHIM]HSO4,[HSO3-pMIM]HSO4,[HSO3-pPydin] HSO4and [HSO3-pPydin]+[pTSA] were synthesized, and characterized by FT-IR and1HNMR. They were used as acid catalyst for the synthesis of MMA by a one-pot method through the hydrogenation and Bamberger rearrangement of o-nitrotoluene in methanol. The effects of the type and amount of ionic liquids, the amount Pt/C, the reaction temperature and pressure were investigated. The results indicated that SO3H-functionalized Br(?)nsted acidic ionic liquids showed higher catalytic activities than other acidic ionic liquids. Under the optimum conditions, using imidazole sulfonic acid hydrogen sulfate ionic liquid as catalyst, the conversion of o-nitrotoluene was93%, and the selectivity to MMA was79%.The ionic liquid [HSO3-pHIM]HSO4was immobilized using impregnation, sol-gel and grafting method, respectively, in order to make the recycling easily. The results show that the immobilized ionic liquid prepared by impregnation method was serious loss. It would take a long time and many steps to prepare the immobilized ionic liquids when choose the grafting method. So the sol-gel method is the best because of its relative stability and good catalytic performance.Based on the above study, immobilized IL [HSO3-pMIM]HSO4catalyst was prepared using sol-gel method. The effects of the amount of hydrochloric acid and TEOS on the supporting intension of [HSO3-pMIM]HSO4were investigated. Then it was used in the hydrogenation and Bamberger rearrangement of o-nitrotoluene in methanol to2-methyl-4-methoxyaniline by a one-pot method. The results showed that the conversion of o-nitrotoluene was100%and the selectivity to MMA was45.23%over the catalyst system when the amount of hydrochloric acid and TEOS was4ml and10ml. After reused3times, the catalyst system still showed good selectivity to MMA.