The Carboxylation of Phenol Derivatives. V.

Synthesis of p-Aminosalicylic Acid from Alkali Salts of m-Aminophenol in Dimethylformamide.

Abstract

It was found that the potassium and sodium salts of m-aminophenol gave p-aminosalicylic acid (PAS) by heating under carbon dioxide pressure in dimethylformamide, an aprotic polar solvent. The effects of reaction time, reaction temperature, carbon dioxide pressure, alkali carbonates added, and water on the yields of PASand the by-product, 4-amino-6-hydroxyisophthalic acid, were also studied.The alkali salts of m-aminophenol were readily carboxylated. This reaction is accelerated by the addition of potassium carbonate and depressed when a small amount of water is present.