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EPR study of radical intermediates from the oxidation of 6-ethoxy-2,2,4-trimethyl- and 6-ethoxy-2,2,4,8-tetramethyl-1,2-dihydroquinoline

Gunstone, Frank D. and Mordi, Raphael C. and Thorission, Snorri and Walton, John C. and Richard, Jackson A. (1991) EPR study of radical intermediates from the oxidation of 6-ethoxy-2,2,4-trimethyl- and 6-ethoxy-2,2,4,8-tetramethyl-1,2-dihydroquinoline. Journal of the Chemical Society, Perkin Transactions , 2 (12). pp. 1955-1958.

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Abstract

The EPR spectra of 1,2-dihydro-6-ethoxy-2,2,4-trimethyl- and 1,2-dihydro-6-ethoxy-2,2,4,8-tetramethyl-quinolin-1-yl radicals were observed in heptane solution. The hyperfine splittings showed that this class of radical is extensively delocalised with significant spin density at C(8). Both radicals decayed by second-order processes, the rate constants being 5 × 106 and 4 × 102 dm3 mol–1 s–1, respectively at 273 K. The latter reaction is much slower because the 8-methyl substituent blocks the formation of the 1,8′-dimer. Both radicals reacted with oxygen to give the corresponding nitroxides, although reaction was very slow for the 8-methyl derivative. A mechanism is proposed to rationalise product formation from 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline when used as an antioxidant

Item Type: Article
Subjects: Q Science > QD Chemistry
Divisions: Faculty of Engineering, Science and Mathematics > School of Chemistry
Depositing User: Mrs Patricia Nwokealisi
Date Deposited: 24 Nov 2015 13:08
Last Modified: 24 Nov 2015 13:08
URI: http://eprints.covenantuniversity.edu.ng/id/eprint/5660

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