Electron paramagnetic resonance spectroscopic study of nitroxide radicals formed from oximes

Abstract

The addition of hydroxyl radicals to each of the oximes, acetaldoxime, acetoxime, and 2,3-butanedione monoxime, has been studied by mixing titanous chloride, hydrogen peroxide, and the oxime in an aqueous continuous-flow system. In each case a β-hydroxy nitroxide (functional structure [Formula: see text] is formed. In confirmation of these results, amino and hydroxymethyl radicals were added to the oximes using similar procedures to give in each case the radicals of functional structure [Formula: see text] and [Formula: see text], respectively. Attempts to add methyl radicals, prepared by the reaction between titanous chloride and t-butyl hydroperoxide, to these oximes gave no observable products save the methyl radicals. However, use of titanous chloride and peracetic acid gave results consistent with the addition of hydroxyl radicals. The addition of hydroxyl radicals to the oxime-O-methyl ethers of acetaldehyde and acetone gave radicals of functional structure [Formula: see text][Formula: see text] which have not previously been identified unambiguously. On the assumption that |QN| = |QHNH| = 23 G in all these radicals, ρNπ has been calculated and used to obtain a value for [Formula: see text] of ca. 11 G which is within the range of other estimates in the literature.