Synthesis
General procedure for the synthesis of 2-amino-5-methylbenzoic acid from 5-methyl-2-nitrobenzoic acid: 5-methyl-2-nitrobenzoic acid (20 g, 110 mmol) was dissolved in ethanol and 10% palladium/carbon catalyst (1 g) was added. The reaction mixture was stirred overnight at room temperature and under hydrogen atmosphere. Upon completion of the reaction, the catalyst was removed by filtration through diatomaceous earth and the filtrate was concentrated under reduced pressure to give 16 g (96% yield) of the white solid product 2-amino-5-methylbenzoic acid. Melting point: 162 °C. 1H NMR (DMSO-d6) δ: 2.13 (s, 3H), 6.65 (d, J=8.6 Hz, 1H), 7.06 (dd, J=8.6,1.8 Hz, 1H), 7.48 (d, J=1.1 Hz, 1H).EIMS m/z: 174 (M+1), 152 (M+23).
References
[1] Patent: WO2004/74218, 2004, A2. Location in patent: Page 97
[2] Patent: US2008/139551, 2008, A1. Location in patent: Page/Page column 41
[3] Journal of Organic Chemistry, 2016, vol. 81, # 19, p. 9046 - 9074
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[5] Chemische Berichte, 1905, vol. 38, p. 3555