Journal Articles (before-1995)

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Author: search.filters.author.Clark, K. P.Subject: search.filters.subject.Radiation Chemistry

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    Photochemistry and Radiation Chemistry of Anthraquinone-2-sodium-sulphonate in Aqueous Solution: Part 1.—Photochemical Kinetics in Aerobic Solution
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (4), 1972) Clark, K. P.; Stonehill, H. I.
    When aqueous solutions of anthraquinone-2-sodium-sulphonate (D) are photolyzed the quinone becomes hydroxylated and (in the absence of oxygen) reduced. On the basis of the kinetics of the photohydroxylation in air or oxygen saturated solutions (pH 2–14), two alternative mechanisms are proposed, the 3D*/S (S = H2O or OH–) and the 3D*/D. In the former, D attacks S to produce an adduct DOH– which is converted by ground-state D to the radical DOH·. In the latter, 3D* attacks D to form a solvent caged radical pair {D·+ D·–}, the D·+ constituent then reacting with S to give OH· radicals which with D yield DOH·. This intermediate is converted by oxygen to hydroxy product. Neither continuous irradiation kinetics nor conventional µs flash photolysis permits discrimination between these schemes. The thermodynamic feasibility of OH· production by the 3D*/D reaction is demonstrated.
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    Photochemistry and Radiation Chemistry of 9,10-Anthraquinone-2-sodium Sulphonate in Aqueous Solution: Part 2.—Photochemical Products 1
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (9), 1972) Clark, K. P.; Stonehill, H. I.
    Anthraquinone-2-sodium sulphonate in “aqueous” solutions within the range pH 14 to 100% H2SO4(and also in oleum) is both reduced and hydroxylated when irradiated with u.v. or visible light. The major hydroxy-photoproducts were isolated and identified as a 3 : 2 mixture of isomeric α-and β-hydroxy derivatives of the starting material in the range 40 % H2SO4 to pH 9; outside this region the relative amount of α isomer produced falls off rapidly and in strong acid or alkali only the β-hydroxy product is obtained. Prolonged irradiation produces also small amounts of polyhydroxy derivatives. The pH-dependence of the ratio of α- and β-hydroxy product yields is correlated with ionization of hydroxyl radical adduct intermediates.