SYNTHESIS AND SPIN-TRAPPING APPLICATIONS OF DIMETHYL-D(6)-4-METHYL-2H-IMIDAZOLE-1-OXIDE-1-N-15

A new spin trap, dimethyl-d(6)-4-methyl-2H-imidazole-1-oxide-1-N-15 (l TMIO), was synthesized and characterized. Hyperfine splitting (HFS) co nstants of spin adduct ESR spectra of this compound with oxygen-center ed, carbon-centered, thiyl and sulfite-derived radicals were determine d and compared with the data of the unsubstituted compound. The increa se in ESR spectral intensity and the accompanying decrease of the spec tral linewidth result in resolution of the HFS due to interaction with alpha-protons of alkyl radicals trapped by lTMIO. Trapping of the for mate radical in deoxygenated aqueous solution revealed a very low spec tral linewidth (Delta B-pp = 0.028 mT) of the corresponding adduct. A strong dependence of the ESR spectra on pH was observed when the autox idation product of sulfite, SO3.-, was trapped. The pK(a) was found to be 5.8 +/- 0.3. In comparison to other nitrones, application of this spin trap provides more detailed information on the structure of the s pecies trapped, especially for carbon-centered radicals.