Study of the isolation and stability of α-trichloromethylbenzyl(tert-butyl)aminoxyl, the trichloromethyl radical adduct of α-phenyl-tert-butylnitrone (PBN)

The aminoxyl produced from trapping trichloromethyl radicals by α-phenyl-tert-butylnitrone (PBN) has been isolated. Isolation has been achieved from the metabolism of carbon tetrachloride by rat liver microsomal dispersions followed by extraction or by photolysis of bromo(trichloro)methane in benzene. Chromatographic techniques were used to purify the isolated aminoxyl. The stability of this spin adduct aminoxyl has been evaluated in various solvents and at different pH in buffer solutions. The intrinsic stability of this spin adduct is remarkable. Solutions of this aminoxyl survive in aromatic solvents almost unchanged for over 90 days. In aqueous media the spin adduct is stable for over 30 days. Light and low pH cause decay but the rates are moderate. The spin adduct is difficult to oxidize and slow to reduce. The outstanding stability of this alkyl spin adduct must be associated in some manner with the proximity of the trichloromethyl group.