p-Toluenesulfonic acid → Methyl 2-chloro-3-nitrobenzoate

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Reaction Steps

To a suspension of 2-chloro-3-nitrobenzoic acid (100 g, 495 mmol) in MeOH (600 mL) was added TsOH (20 g, 10%). Then the mixture was heated at reflux overnight. The solvent was removed. The residue was diluted with EtOAc (1 L). Then the pH was adjusted to around 9 by progressively adding saturated NaHCO3. The organic layer was separated. The aqueous layer was extracted with EtOAc (1 L×3). The combined organic layers were washed with water and brine successively, dried over Na2SO4, filtered and concentrated under reduced pressure to give the title compound (96 g, 90.6% yield). 1H NMR (400 MHz, CDCl3) δ ppm 7.90 (dd, J=1.8 Hz, 7.9 Hz, 1H), 7.81 (dd, J=1.5 Hz, 7.7 Hz, 1H), 7.45 (dd, J=7.7 Hz, 7.9 Hz, 1H), 3.94 (s, 1H).

Provenance & Evidence