50-30-6

55775-97-8

Step a: Synthesis of 2,6-dichloro-3-nitrobenzoic acid 2,6-Dichlorobenzoic acid (10 g, 52 mmol) was added to a pre-stirred mixture of nitric acid (15 mL) and sulfuric acid (30 mL) and reacted at 55 °C for 30 min, followed by continued stirring at room temperature for 30 min. Upon completion of the reaction, the reaction mixture was slowly poured into ice-cold water (1 L) and the precipitated solid was filtered and dried to afford 2,6-dichloro-3-nitrobenzoic acid (9 g). The filtrate was extracted with ethyl acetate (2 x 200 mL), the organic layers were combined, dried over anhydrous sodium sulfate and concentrated to dryness to give the additional product (2 g). The total yield was 11 g in 88% yield. 1H NMR (400 MHz, MeOH-d4): δ 7.98 (d, J=8.8 Hz, 1H), 7.67 (d, J=8.8 Hz, 1H).