Spectral and kinetic measurements on a series of persistent iminoxyl radicals

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Department of Chemistry


A series of new iminoxyl radicals, Et3C(C=NO•)Bu-tert (1), tert-C5H11(C=NO•) Bu-tert (2), (tert-C5H11)2C = NO• (3), Et3C(C=NO•)Ph (4), PhCH2CMe2(C=NO•)Bu-tert (5), PhMe2(C=NO•)Bu-tert (6) and Me2CH(C=NO•)C5H11-tert (7), was characterized by EPR and in some cases visible spectra and decay kinetics in solution. Isolation of 1H and 3-tert-butyl-4,4-diethyl-5-methyl-4,5-dihydro-5-isoxazolol (9) among the decomposition products of 1 was consistent with a previously unrecognized mode of iminoxyl reaction in which the initial step is an internal β-H abstraction. Molecular orbital calculations on H2C=NO• indicate a C-N-O angle of about 140° and a 10 kcal mol-1 barrier to inversion. Rate constants for the reaction of tert-Bu2C=NO• (8) with a series of olefins were measured.

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Journal of Physical Organic Chemistry