26830-95-5

153775-42-9

Example 17: Alternative preparation of 4-cyano-3-nitrobenzoic acid Periodic acid (492 g, 2.17 mol) was dissolved in acetonitrile (7.71 L) under an inert atmosphere with vigorous stirring. after 15 min, chromium (VI) oxide (25 g, 0.25 mol) and 4-methyl-2-nitrobenzonitrile (100 g, 0.62 mol) were added sequentially. The reaction mixture was stirred at room temperature for 16 hours. The reaction mixture was decanted and the supernatant was filtered. The filtrate was concentrated and the residue was partitioned between 1 M aqueous sodium carbonate solution and dichloromethane. The precipitate was separated by filtration to give 4-cyano-3-nitrobenzoic acid (150 g). The filtrate was extracted twice with dichloromethane and then acidified with aqueous 4N hydrochloric acid to pH 1. The acidified filtrate was extracted three times with dichloromethane. The organic extracts were combined, dried over sodium sulfate and concentrated. The residue was partitioned between 1 M aqueous sodium carbonate and dichloromethane. The precipitate was separated by filtration to give 4-cyano-3-nitrobenzoic acid (26.67 g). Total yield: 150 g + 26.67 g = 176.67 g; 74.5% yield.