1. 3-Hydroxy-5-nitrobenzoic acid (3.7 g, 20.00 mmol) was dissolved in methanol (70.0 mL) at 0 °C.
2. Thionyl chloride (12.0 mL) was slowly added to the above solution.
3. The temperature of the reaction mixture was raised to 6 °C and stirred continuously for 3 hours.
4. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure.
5. Water was added to the residue and subsequently extracted with ethyl acetate.
6. The organic phases were combined, washed with saturated brine and dried over anhydrous sodium sulfate.
7. After filtration, the organic phase was concentrated under reduced pressure to afford the crude product methyl 3-hydroxy-5-nitrobenzoate (3.9 g) as an off-white solid which did not require further purification. 8. The structure of the product was determined by 1H-1H-beta-hydroxy-5-nitrobenzoic acid.
8. The structure of the product was confirmed by 1H-NMR (300 MHz, DMSO-d6): δ 10.96 (s, 1H), 8.08 (m, 1H), 7.78 (m, 1H), 7.70 (m, 1H), 3.90 (s, 3H).
