Analgesic and Antipyretic Activities of 4-Hydroxyisophthalic Acid

4-HYDROXYisoPHTHALIC acid is a by-product of the manufacture of salicylic acid by the Kolbe-Schmitt reaction and has been found to be a major constituent of the `brown dust' residues from the sublimation process for the purification of salicylic acid<sup>1</sup>. Analysis of a typical sample of `brown dust' showed it to contain 10 per cent of salicylic, 82 per cent of 4-hydroxyisophthalic and 3 per cent of 2-hydroxyisophthalic acids, together with some inorganic material. From this source there is thus potentially available a considerable quantity of 4-hydroxyisophthalic acid, the chemistry of which is being investigated as part of a research programme on the Kolbe-Schmitt reaction at the Chemical Research Laboratory². From a consideration of its structural similarity to salicylic acid, it was suggested at the Chemical Research Laboratory that 4-hydroxyisophthalic acid might also possess similar pharmacological properties. Accordingly, in February 1954, a pharmacological investigation was initiated at Ware and, since the findings were favourable, biochemical studies were also undertaken.