Synthesis
At room temperature and under hydrogen atmosphere, 3-methyl-4-nitrobenzoic acid (100 g, 552.04 mmol) was dissolved in methanol (2000 mL) followed by addition of palladium carbon catalyst (5.0 g). The reaction mixture was stirred continuously at room temperature for 24 hours. Upon completion of the reaction, the solid catalyst was removed by filtration. The filtrate was concentrated under reduced pressure to give the light yellow solid product 4-amino-3-methylbenzoic acid (80 g, 96% yield).
References
[1] Advanced Synthesis and Catalysis, 2010, vol. 352, # 9, p. 1451 - 1454
[2] Patent: WO2014/66795, 2014, A1. Location in patent: Paragraph 0175
[3] Journal of Organic Chemistry, 2008, vol. 73, # 21, p. 8631 - 8634
[4] Patent: CN106831460, 2017, A. Location in patent: Paragraph 0029-0059
[5] Patent: CN107501106, 2017, A. Location in patent: Paragraph 0025-0047