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KINETIC STUDIES ON ANTHRALIN PHOTOOXIDATION
Author(s) -
Müller Klaus,
Kanner Richard C.,
Foote Christopher S.
Publication year - 1990
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.1751-1097.1990.tb01785.x
Subject(s) - chemistry , photochemistry , kinetic energy , physics , quantum mechanics
— The photooxidation of the antipsoriatic drug anthralin (1,8‐dihydroxy‐9‐anthrone) has been studied by several kinetic techniques, including direct observation of 1 O 2 ( 1 Δ g ) luminescence at 1.27 μm. The rate of deactivation of 1 O 2 increases at higher pH, demonstrating that the trihydroxy‐anthracene anion is the reactive species. Direct determination of the rate constant of 1 O 2 deactivation ( k R +k Q ) in deuterated buffer systems by luminescence quenching gave a value of 3.0 times 10 8 M −1 −1 for the anion; the neutral anthrone is unreactive. The rate constant for the neutral anthrone in benzene‐ d 6 is 2.8 times 10 4 M −1 s −1 Competition experiments with tetramethylethylene in acetonitrile gave a rate constant for reaction alone ( k R ) of 2.1 times 10 8 M −1 s −1 for the anion.