An EPR study of free radicals derived from 1,3-dioxolan-4-one and related compounds

Abstract

Electron paramagnetic resonance (EPR) spectra have been recorded during UV irradiation of di-tert-butyl peroxide in the presence of α-methyl-γ-butyrolactone (2), tetrahydrofuran-3-one (3), and the substituted 1,3-dioxolan-4-ones 4–10. tert-Butoxyl radicals abstract hydrogen atoms from the α-position of 2, position 2 of 3, and positions 2 and 5 of 4–10. The EPR parameters determined from the spectra include exceptionally large hyperfine splitting constants due to the γ-protons in the radicals derived from 4–10. The reactivities per equivalent hydrogen atom of tetrahydrofuran (1) and the substrates, 2–20, relative to the reactivity of a methoxy hydrogen atom of tert-butyl methyl ether (11) have been estimated from digitised EPR spectra, and these reactivities are discussed.