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Oxygen uptake upon photolysis of 3-benzoylpyridine and 3,3′-dipyridylketone in air-saturated aqueous solution in the presence of formate, ascorbic acid, alcohols and amines

Paper ID Volume ID Publish Year Pages File Format Full-Text
29333 44154 2007 8 PDF Available
Title
Oxygen uptake upon photolysis of 3-benzoylpyridine and 3,3′-dipyridylketone in air-saturated aqueous solution in the presence of formate, ascorbic acid, alcohols and amines
Abstract

The effects of oxygen in the photolysis of 3-benzoylpyridine (3-By) and 3,3′-dipyridylketone (3,3′-Dy) in aqueous solution were studied in the presence of appropriate donors: formate, ascorbic acid, amines, e.g. triethylamine and alcohols, e.g. 2-propanol. The quantum yield of oxygen uptake (Φ−O2)(Φ−O2) increases with the donor concentration, approaching Φ−O2=0.6Φ−O2=0.6, e.g. for ascorbic acid or triethylamine (>1 mM) and 2-propanol (>0.1 M). Quenching of the triplet state by the donor and subsequent reaction of both acceptor and donor radicals with oxygen leads to formation of hydrogen peroxide. The radicals of the mono- and dipyridylketones terminate into an “iso”benzpinacol-type product. This reaction is minor and major in the presence and absence of air, respectively. For N-methylphthalimide, a related heterocyclic sensitizer, the mechanism of oxygen uptake is the same: oxidation of the donor and conversion of oxygen via the hydroperoxyl radical into H2O2, but the Φ−O2Φ−O2 values are smaller. The relevant properties of donors, the radicals involved and the pH and concentration dependences are discussed.

Keywords
Superoxide radical; Triplet; Photooxidation; Photoreduction; Electron transfer
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Oxygen uptake upon photolysis of 3-benzoylpyridine and 3,3′-dipyridylketone in air-saturated aqueous solution in the presence of formate, ascorbic acid, alcohols and amines
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 187, Issue 1, 5 March 2007, Pages 105–112
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
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Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
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