An Electron Spin Resonance Study of the Arylsilyl Adducts of Phenyl tert-Butyl Nitrone and Their Decomposition Kinetics

Abstract

The formation and the stability of some arylsilyl adducts of phenyl tert-butyl nitrone were studied in a photochemical system using di-tert-butyl peroxide as solvent. The β-proton splittings of all the arylsilyl adducts, ranging from 5.6 to 8.3 G, are relatively larger than their carbon analogs, which are usually less than 4 G. The arylsilyl adducts are found to decompose in di-tert-butyl peroxide solvent by a first-order kinetics. The activation energy involved in the decomposition of a series of arylsilyl adducts varies from about 14 to about 9 kcal/mol, as the size of the silyl group increases. In all cases, very low values of the A factors (between 106 and 1010) were observed.