Acetic Acid → 1,3-Benzenedicarboxylic acid, 5-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)-

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Reaction Steps

211.2 g (1.0 mol) of 5-nitroisophthalic acid are dissolved in 1,590 g of aqueous sodium hydroxide (90.0 g of sodium hydroxide in 1,500 ml of water) and the solution is rendered neutral with 15 ml of anhydrous acetic acid and hydrogenated in the presence of 10 g of a palladium-on-charcoal catalyst (5% by weight of Pd). The catalyst is filtered off and a solution of 118.0 g (1.2 mols) of maleic anhydride in 150 ml of dioxane is added to the filtrate in the course of 2 hours, whilst stirring vigorously. A white suspension is formed and is stirred overnight at 20°-25° C., 250 ml of acetic acid are then added and the mixture is stirred for a further 2 hours. The amide-acid which has precipitated is filtered off, washed with water and methanol and dried at 30° C. in vacuo for 24 hours. The reaction product (315 g) is then heated, in 2,500 ml of acetic anhydride, whilst stirring, to 80°-85° C. for 30 minutes. About 1.8 liters of liquid (acetic acid + acetic anhydride) are distilled off under a waterpump vacuum. The residual suspension is poured onto 2,000 g of ice and the mixture is stirred overnight. The reaction product which has precipitated is filtered off, washed with water and methanol and dried at 60° C. in vacuo for 12 hours. 210 g of white, crystalline 5-maleimidylisophthalic acid are obtained; melting point > 300° C. (= 80% of theory, based on the nitroisophthalic acid).

Provenance & Evidence