Electron-transfer photochemistry of thianthrene. Nucleophile-assisted photooxidation to sulfoxide

Journal Article · Fri Apr 09 04:00:00 EDT 1993 · Journal of Organic Chemistry; (United States)

DOI:https://doi.org/10.1021/jo00060a016· OSTI ID:5620300

Jones, G II; Huang, B; Griffin, S F ^[1]

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1. Boston Univ., MA (United States)

The photochemistry of thianthrene (1) in the presence of a variety of electron acceptors in acetonitrile/water has been investigated. Diffusion-limited rates of fluorescence quenching were observed on excitation of 1 (with fumaronitrile and with methyl phthalate). Alternatively, addition of 1 led to quenching of the fluorescence emission of ketones, biacetyl, and fluorenone and to the quenching of the excited triplet states of quinones such as 2,5-dichloro-p-benzoquinone (5) and 9,10-anthraquinone (3). Steady irradiation of 1 with selected acceptors results in photooxidation yielding the sulfoxide (2) and the expected photoreduction products. The electron-transfer mechanisms were further studied by laser flash photolysis. The quenching of ketone triplets by 1 resulted in formation of the radical cation of 1([lambda][sub max]540 nm). The decay of this species and its dependence on the concentration of water present were determined; the bimolecular rate constant for trapping of 1[sup [center dot]+] by water in acetonitrile-water solution is 4.9 x 10[sup 4] M[sup [minus]1]s[sup [minus]1] under conditions in which 5 acts as a sensitizer. The nucleophilic trapping of the 1 radical cation by imidazole ([kappa] = 3.6 x 10[sup 7] M[sup [minus]1] s[sup [minus]1]) was also investigated. The mechanism of photoinduced two-electron oxidation of 1 and the role played by nucleophiles in facilitating the reaction are discussed in detail. 37 refs., 9 figs., 2 tabs.

• OSTI ID: 5620300
• Journal Information: Journal of Organic Chemistry; (United States), Journal Name: Journal of Organic Chemistry; (United States) Vol. 58:8; ISSN 0022-3263; ISSN JOCEAH
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
AROMATICS
CATIONS
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELECTRON TRANSFER
FLUORESCENCE
IONS
KETONES
KINETICS
LASER RADIATION
LUMINESCENCE
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDATION
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
QUENCHING
QUINONES
RADIATIONS
RADICALS
REACTION KINETICS