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Photocatalytic Activity of Anthraquinone Derivatives in Photochemical Reduction of Azo Dyes
Author(s) -
BEEK H. C. A.,
HEERTJES P. M.,
VISSCHER F. M.
Publication year - 1965
Publication title -
journal of the society of dyers and colourists
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 0037-9859
DOI - 10.1111/j.1478-4408.1965.tb02676.x
Subject(s) - chemistry , mandelic acid , semiquinone , photochemistry , anthraquinone , radical , hydrogen atom abstraction , organic chemistry , quinone
Azo dyes are photoreduced rapidly when solutions in water also containing dl–mandelic acid are exposed to ultraviolet radiation. Since the active reducing species in this reaction is formed from the photoexcited mandelic acid, the wavelength region responsible for the fading coincides with the region in which mandelic acid absorbs. The photoreduction reaction can be sensitised to longer wavelengths by the addition of sodium–9, 10–anthraquinone–2–sulphonate. The mechanism of sensitisation has been investigated and it has been found that semiquinone radicals are formed by hydrogen abstraction from dl–mandelic acid by the photoexcited anthraquinone derivative. The semiquinone radicals can reduce the azo dyes to the corresponding amines, the quantum efficiency of this reaction being almost unity.