Itaconic acid → 2-{[(1H-Benzimidazol-2-yl)sulfanyl]methyl}butanedioic acid

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Reaction Steps

47.4 g of 2-mercaptobenzimidazole and 40.7 g of itaconic acid, mixed in finely powdered form, are introduced into 150 ml of 70% aqueous sulfuric acid in the course of 1 hour. The temperature is kept at 40° to 43°, with stirring. The mixture is then allowed to react completely at the above temperature over a period of 11/2 hours and the reaction mixture is diluted with water and ice to about 2 liters. The product is precipitated by addition of 30% aqueous sodium hydroxide solution to pH 4 and filtered off. After washing with water and drying in vacuo at about 30°, 92.5 g of 3-(benzimidazol-2-ylthio)-propane-1,2-dicarboxylic acid are obtained in the form of a dihydrate of melting point 113° (decomposition), corresponding to 97% of theory.

Provenance & Evidence