Acetic Acid → N-(2-fluoro-4-chloro-5-carboxyphenyl)-2,3-dimethylmaleic acid imide

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Reaction Steps

11.4 g of N-(2-fluoro-5-carboxy-4-aminophenyl)-2,3-dimethylmaleic acid imide are introduced in portions, at a temperature of 25°-30°, into 60 ml of glacial acetic acid and 60 ml of 96% sulphuric acid and the whole is stirred at that temperature for 1 hour. The solution is then stirred at 5° and an aqueous solution of 2.9 g of sodium nitrite in 17 ml of water is added dropwise thereto. The resulting diazo solution is added in portions, while stirring vigorously at 30°, to a solution of 4.5 g of copper(I) chloride in 32 ml of concentrated hydrochloric acid. When the evolution of nitrogen has ceased, the reaction mixture is heated at 60° for a further 30 minutes, while stirring, and then poured onto ice. The product which precipitates is filtered with suction, washed with water and recrystallised from methanol/water. 9.8 g of N-(2-fluoro-5-carboxy-4-chlorophenyl)-2,3-dimethylmaleic acid imide having a melting point of 230°-231° are obtained.

Provenance & Evidence