Sodium Hydroxide → 4-Amino-3-chlorobenzoic acid

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The benzoate ester (2), 45.5 g (0.23 moles), was dissolved in 250 mL of hot MeOH and then 230 mL of 3N NaOH (3 equivalents, 0.69 moles) was added. The mixture was stirred at reflux for 5 hours. The solution was concentrated on a rotary evaporator at 80° C. to remove the MeOH and then the mixture was acidified to pH 2 with 3N HCl. The precipitated solids were filtered on a sintered glass funnel and washed with water. The product was homogeneous by TLC (Hexane: EtOAc, 4:1, Rf=0.1) and therefore was not further purified. The white solid was dried at 70° C. in a vacuum oven to give 38.1 (97%) of 4-amino-3 chlorobenzoic acid (3), mp 225-226° C. 1H NMR (DMSO d6) d 7.70 (d, 1H, J=0.9 Hz, ArH), 7.61-7.56 (dd, 1H, J=0.7 Hz, ArH), 6.78 (d, 1H, J=3.4 Hz, ArH), 6.15 (bs, 2H, NH2). IR (KBr) cm−1, 3515, 3410 (NH2, m), 1675, (C═O, s) 1640. MS(El) m/e 171 (M+), 173 (M+2). Anal. Calc'd for C7H6NO2Cl: C, 49.00; H, 3.62; N, 8.16. Fd. C, 49.22; H, 3.71, N, 7.9. The formula is:

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