Structural analysis of substituted 3-arylazo-2-hydroxy-6-pyridones

Abstract A structural analysis of substituted 3-arylazo-2-hydroxy-6-pyridones was based on the detection of the 2-hydroxy-6-pyridone coupling component by reaction of the dye with zinc and resorcinol in dilute ammonia, when a blue-coloured air oxidation product is formed. Identification of the 2-hydroxy-6-pyridone component was made using chromatographic comparison of the coloured product of the indophenol reaction with an authentic product and by fragmentation of the 2-hydroxy-6-pyridone component by the action of stannous chloride in concentrated hydrochloric acid, in conjunction with chromatographic identification of the characteristic products and also with data from IR, 1 H-NMR, 13 C-NMR and mass spectra. These techniques afforded a useful overall method for the identification of the structure of dyes of this type.