ISSN:
0749-1581
Keywords:
Quinone cation radicals
;
Photo-induced electron transfer
;
ESR
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Benzoquinone cation radicals of 1,4-benzoquinone and methyl-, 2,5-dimethyl- and 2,6-dimethyl-1,4-benzoquinone were formed from the corresponding parent quinones by in situ UV photolysis in trifluoroacetic acid at ambient temperature, and detected by ESR. The cationic character of the radical species was confirmed by the electron transfer between the quinone cation radicals and N,N,Ń,Ń-tetramethyl-p-phenylenediamine (TMPD). In the case of tert-butyl substituted benzoquinones, instead of the corresponding cation radicals, cyclized radicals, i.e. the 3,3-dimethylcoumaran-5-oxy and 3,3-dimethyl-7-tert-butylcoumaran-5-oxy radicals and the 3,3-dimethyl-6-tert-butylcoumaran-5-hydroxy cation radical were detected from tert-butyl, 2,6-di-tert-butyl- and 2,5-di-tert-butyl-1,4-benzoquinones, respectively. A mechanism involving electron transfer between the photoexcited quinone and that in the ground state is proposed.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260260709
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