Color Reactions of 3-Methyl-2-benzothiazolone Hydrazone with Phenol Derivatives. I. The Spectrophotometric Microdetermination of Catechol, Hydroquinone and Resorcinol

Abstract

Abstract New spectrophotometric procedures for determining microgram amount of catechol, hydroquinone and resorcinol with MBTH have been described. The sensitivities and selectivites of the reaction are largely dependent on the pH and on the conditions of oxidation: 1) In an ammoniacal medium MBTH gives a stable pink color with catechol and, with hydroquinone, a blue color which is srabilized by acetone. Resorcinol gives only a faint color under these conditions. 2) When ferricyanide is used as a oxidant in a weakly alkaline solution, MBTH gives a sensitive orange color with resorcinol. 3) In an acidic ferric-ferrous redox catechol. At pH 3 the reaction is selective for catechol. 4) Ferric chloride in 1.2n hydrochloric acid is favorable for the determination of hydroquinone and resorcinol in a mixture of the two.