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Oxygen Uptake and Involvement of Superoxide Radicals upon Photolysis of Ketones in Air‐saturated Aqueous Alcohol, Formate, Amine or Ascorbic Acid Solutions
Author(s) -
Görner Helmut
Publication year - 2006
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 - 10.1562/2005-12-06-ra-746
Subject(s) - chemistry , benzophenone , radical , photochemistry , ascorbic acid , triethylamine , acetophenone , ketone , aqueous solution , hydrogen peroxide , amine gas treating , formate , acetone , quenching (fluorescence) , inorganic chemistry , organic chemistry , catalysis , physics , food science , quantum mechanics , fluorescence
The photolysis of acetophenone, benzophenone, 4‐carboxy‐benzophenone and benzil was studied in air‐saturated aqueous solution in the presence of alcohols. The overall reaction is an oxidation of 2‐propanol to acetone. The quantum yield of oxygen uptake (φ ‐O2 ) increases with increasing 2‐propanol concentration up to 0.9. The photoreaction can also be initiated by quenching of the ketone triplet state by ascorbic acid, formate or an amine e.g . triethylamine. Subsequent reactions of the involved radicals with oxygen yield the super‐oxide radical and eventually hydrogen peroxide. For the ketones in the presence of 3–30 m M ascorbic acid or triethylamine φ ‐O2 = 0.3–0.9. The specific properties of ketones, including 4‐methoxyacetophenone and 2‐acetonaphthone, the radicals involved and the pH and concentration dependences of φ ‐O2 are discussed.