Fourier transform electron paramagnetic resonance study of the photoreduction of anthraquinone with 4-methyl-2,6-di-tert-butylphenol in alcoholic solutions

Journal Article · Thu Oct 29 04:00:00 EST 1992 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/j100201a026· OSTI ID:458797

Plueschau, M; Kroll, G ^[1]; Dinse, K P ^[2]

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1. Universitaet Dortmund (Germany)
2. TH Darmstadt (Germany); and others

Using FT-EPR following laser excitation, the primary photochemical process in the photoreduction of anthraquinone with 4-methyl-2,6-di-tert-butylphenol was investigated. High-resolved spin-polarized EPR spectra taken with nanosecond time resolution gave unambiguous evidence for a two-step hydrogen abstraction reaction, consisting of a primary electron transfer followed by proton abstraction with a time delay, which allows for a noticeable escape probability of the initially generated anthrasemiquinone radical anion (AQ{sup {sm_bullet}minus}). The time dependence of the EPR intensities of the neutral 10-hydroxy-anthroxyl radical (AQH{sup {sm_bullet}}) as well as of AQ{sup {sm_bullet}} could be simulated for the full experimentally accessible time interval of 10 ns to 100 {mu}s. The kinetic model used invokes optical spin polarization, spin-lattice relaxation, radical generation, and AQH{sup {sm_bullet}}AQ interconversion. In addition, from an analysis of the highly-resolved FT-EPR spectra a complete set of AQH{sup {sm_bullet}} hyperfine splitting (hfs) constants could be measured in two different alcohols for the first time. 30 refs., 4 figs., 2 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 458797
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 22 Vol. 96; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
66 PHYSICS
ALCOHOLS
ANTHRAQUINONES
FOURIER TRANSFORMATION
METHYL RADICALS
PHENOLS
PHOTOCHEMICAL REACTIONS
REDUCTION