Catalytic Synthesis Of 4-methoxy-2-methyl-n-phenylaniline By Pd/C Catalysts

4-Methoxy-2-methyl-N-phenylaniline(DPA),as an important organic intermediate,was used as a key intermediate for the synthesis of heat-sensitive and pressure-sensitive dyes.This paper adopted a prevalent synthesis of DPA:2-methyl-4-methoxylaniline(MMA)was condensed with phenol in the presence of Pd/C and a small amount of cyclohexanone.In order to reduce the cost of production,this paper introduced a new method to improve the stability of Pd/C in the catalytic cycles for the synthesis of DPA.Pd/C catalyst was prepared by impregnation method.The effects of raw materials ratio,reaction temperature and the composition of catalysts on the conversion of MMA and the selectivity of DPA were investigated.The results indicated that 10%Pd/C catalyst was suitable for this reaction.With the temperature up tO 230 ?,the conversion of MMA could reach 100%while the selectivity of DPA reached 98%.The properties of Pd/C catalysts such as surface area,pore volume and crystal structure were studied,and the mechanisms of deactivation of the catalysts were researched.The most important reasons of the deactivation of the catalysts are as follows:l.The pores of catalyst were blocked;2.The crystalline phase of catalyst was changed because of the high temperature.A method for improving the stability of Pd/C catalysts was presented in this paper.With this method,the catalyst showed obviously higher stability in reaction cycles,and the cost of this synthesis was greatly reduced.