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STUDIES ON SOME INTERMEDIATES AND PRODUCTS OF THE PHOTOREDUCTION OF 9,10‐ANTHRAQUINONE *,†
Author(s) -
CARLSON STEVEN A.,
HERCULES DAVID M.
Publication year - 1973
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1973.tb06341.x
Subject(s) - anthracene , chemistry , photochemistry , quantum yield , anthraquinone , absorption (acoustics) , flash photolysis , absorption spectroscopy , solvent , fluorescence , ethylene glycol , yield (engineering) , ion , reaction rate constant , organic chemistry , materials science , kinetics , physics , quantum mechanics , metallurgy , composite material
— The mechanism of the photoreduction of 9,10‐anthraquinone (AQ) in alcohol and hexane has been studied by flash photolysis. The fluorescence spectrum of the photoproduct, 9,10‐dihydroxy anthracene shows a large shift between hexane and ethanol. The quantum yields of photoreduction for AQ are solvent‐dependent, the reaction between the solvent radical and AQ determining the quantum yield. The absorption spectrum of the 9,10‐anthrasemiquinone (AQH.) has a long‐wavelength absorption band with peaks at 631 and 678 nm. The second‐order decay constants for AQH. were estimated to be 1.3 × 10 9 , 6.7 × 10 8 and 2.0 × 10 8 M ‐1 sec ‐1 in ethanol, 2‐propanol and ethylene glycol, respectively. A long‐wavelength absorption band was observed for 9,10‐anthrasemiquinone radical anion, having peaks at 776 and 860 nm; epsi; max = 1900 at 776 nm. This spectrum is compared with the spectra of 9,10‐dihydroxy anthracene mono‐ and di‐anions. The 9,10‐anthrasemiquinone radical anion was found to photoreduce quantitatively to 9,10‐dihydroxy anthracene mono‐anion with a quantum yield of 0.1.