Radical products of γ-radiolysis of 12-crown-4 at 77 K

Paramagnetic products of γ-radiolysis of 12-crown-4 and its solutions in CFCl3 and CFCl2CF2Cl at 77 K were studied by ESR spectroscopy. It was found that the ESR spectra of 12-crown-4 irradiated with γ-rays at 77 K contained superimposing signals of at least two species, the radicals resulting from macrocycle opening -ĊH-C(H) = O and macrocyclic radicals -O-ĊH-CH2-, which are formed with nearly equal yields. It was shown that -O-ĊH-CH2-radicals rapidly decayed at temperatures above 140 K. However, the -ĊH-C(H)=O radicals are stable almost up to the matrix softening temperature. The radical cations of 12-crown-4 are not stabilized in the matrices of Freon 11 and Freon 113, since they undergo transformation to macrocyclic radicals -O-ĊH-CH2-via the deprotonation reaction.