Synthesis of 2-Methyl-4-methoxyaniline from o-Nitrotoluene Using Pt/C and Acidic Ionic Liquid as Catalyst System

• Published in: Chinese journal of chemical engineering Vol. 21; no. 6; pp. 701 - 704
• Main Authors: LIU, Yingxin, LI, Xiying, FANG, Yanyan, ZHANG, Lin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2013
• Subjects: 2-methyl-4-methoxyaniline; acidic ionic liquid; Bamberger rearrangement; Catalysts; Conversion; Hydrogenation; Ionic liquids; Methyl alcohol; o-nitrotoluene; Platinum; Polymethyl methacrylates; Selectivity; 一锅法合成; 催化剂体系; 反应压力; 可重复使用; 甲基丙烯酸甲酯; 甲氧基苯胺; 邻硝基甲苯; 酸性离子液体; Bamberger rearrangement; 2-methyl-4-methoxyaniline; acidic ionic liquid; o-nitrotoluene; hydrogenation
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/S1004-9541(13)60499-X

2-Methyl-4-methoxyaniline （MMA） was synthesized by one-pot method through the hydrogenation and Bamberger rearrangement of o-nitrotoluene in methanol using acidic ionic liquid and 3% Pt/C as catalyst system. The effects of ionic liquid type, dosage of ionic liquid and 3% Pt/C, reaction temperature and reaction pressure on o-nitrotoluene conversion and MMA selectivity were investigated. The results indicated that the imidazolium-based acidic ionic liquid which contains SO3H-functionalized cation showed higher selectivity to MMA than other acidic ionic liquids used in this work. Using 1-（propyl-3-sulfonate）-3-methylimidazolium hydrosulfate （[HSO3-pmim][HSO4]） as the acid catalyst, the selectivity to MMA was as high as 67.6% at 97.8% of o-nitrotoluene conversion. As 3% Pt/C increased from 0.01 g to 0.025 g, the selectivity to MMA decreased from 73.4% to 62.5%, because of the hydrogenation of intermediate o-methyl-phenylhydroxylamine to o-toluidine becoming more dominant. An increase in hydrogen pressure also had obviously dramatic effect in lowering the MMA selectivity. After easy separation from the products, the catalyst system could be reused at least 3 times.