Synthesis
The general procedure for the synthesis of 4-amino phthalic acid from 4-nitrophthalic acid was as follows: 1 g (4.73 mmol) of 4-nitrophthalic acid was dissolved in 10 ml of anhydrous ethanol. The solution was stirred and degassed at room temperature and under argon protection. Subsequently, 50 mg of 5% palladium/carbon catalyst was added at once and hydrogen was passed into the solution for hydrogenation reaction. After 3 hours of reaction, the reaction mixture was filtered through diatomaceous earth to remove the catalyst. The filtrate was concentrated by evaporation to give an orange oily product with a mass of 820 mg and a yield of 96%. The structure of the product was confirmed by 1H NMR (DMSO-d6) with the following chemical shifts: 3.32 (1H, s), 5.95 (1H, s), 6.49-6.53 (2H, m), 7.46-7.50 (1H, d, J = 8.8 Hz), 12.33 (2H, COOH, s).
References
[1] Patent: US6689922, 2004, B1. Location in patent: Page column 20
[2] Patent: US6706725, 2004, B1. Location in patent: Page column 11
[3] Chemical Communications, 2017, vol. 53, # 62, p. 8751 - 8754
[4] Justus Liebigs Annalen der Chemie, 1881, vol. 208, p. 230
[5] Journal of the American Chemical Society, 1908, vol. 30, p. 1143
