A color reaction of thioxolone with iodine solution

Abstract

A new method for the identification of thioxolone (4-hydroxy-2H-1, 3-benzoxathio1-2-one), used as antiseborrheic agent, based on the formation of its inclusion compound with iodine has been proposed.Thioxolone and its chlorinated derivatives on filter paper or thin layer plate of silica gel give a blue color, which is similar to that of iodine-starch, with spraying of 0.05 N iodine solution. Oxine and 2-methyloxine indicates same color reaction, although for many other phenolic compounds, such as phenol, resorcinol, salicylic acid, pentachlorophenol etc., and halogenated oxine derivatives, no remarkable color reaction is observed. Because the blue color does not appear in the solution, application of this reagent is limited. As shown in table I, the proposed reaction has not always high sensitivity, but is excellent in selectivity. As an example of application, this has been applied to the thin layer chromatography of alkaline decomposition products of thioxolone.