Abstract
Decolorization of two azo dyes (C. I. Acid Orange 7_??_1a_??_ and C. I. Acid Orange 20_??_2a_??_ by sodium _??_ solution was pursued photometrically at 30°C. The initial decolorization products showing absorption maxima at 413nm for la and 374nm for 2a were isolated as tetrabutylammonium ion-complexes soluble in organic _??_. The measurements of the 1H-NMR and the two-dimensional COSY spectra revealed that the products were not krdrazabenzene derivatives which had been suggested so far, but Michael adducts of sodium sulfite to _??_-form of the dyes. The IR data also supported the structures.
