Abstract
The photoreduction of eighteen different monoazo dyes in aqueous and ethanolic solutions, containing d, l‐mandelic acid or acetone as hydrogen donors, to the corresponding amines has been investigated by flash‐photolysis and rapid‐flow techniques. The photoreduction of azo dyes proceeds in stages involving hydrazyl radicals and hydrazo compounds. The former are formed in a rapid reaction of the azo dyes with the active reducing agent produced upon absorption of light by the hydrogen donor. These radicals are unstable and disproportionate with formation of hydrazo compounds and regeneration of the original azo dye. The hydrazo compounds are also unstable and decompose with formation of amines and regeneration of the dye. The reaction schemes presented are supported by kinetic evidence and electron spin resonance measurements.
Published Version
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