91983-31-2

The general procedure for the synthesis of methyl 5-bromo-2-hydroxy-3-nitrobenzoate from methyl 5-bromo-2-hydroxybenzoate was as follows: Methyl 5-bromo-2-hydroxybenzoate (231 g, 1 mol) was dissolved in concentrated sulfuric acid (500 mL), and cooled down in an ice bath to 0 °C. A mixture of concentrated nitric acid (108 g, 1.1 mol) and concentrated sulfuric acid (120 mL) was added to the above cooled down solution slowly by dropwise addition. The mixture of concentrated nitric acid (108 g, 1.1 mol) and concentrated sulfuric acid (120 mL) was slowly added dropwise to the above cooled solution at 0°C, and the rate of acceleration of the dropwise acceleration was controlled so as to maintain the temperature of the reaction system not exceeding 5°C. After the dropwise acceleration was completed, the ice bath was removed, and the reaction system was allowed to warm up to room temperature naturally, and the reaction was continued at room temperature for 3.5 hrs. The progress of the reaction was monitored by thin layer chromatography (TLC), and after confirming the completion of the reaction, the reaction mixture was slowly poured into crushed ice (2 L) and stirred until the crushed ice completely melted, at which time a large amount of light yellow solid precipitated from the system. The solid was collected by filtration, washed to neutrality with ice water and dried to give methyl 5-bromo-2-hydroxy-3-nitrobenzoate (243 g) as a light yellow solid in 88% yield.

[1] Patent: CN107573336, 2018, A. Location in patent: Paragraph 0096; 0097; 0098
[2] Patent: US2009/197863, 2009, A1. Location in patent: Page/Page column 56
[3] Chemical and Pharmaceutical Bulletin, 1992, vol. 40, # 3, p. 624 - 630