The nature and photochemistry of 2,2-dimethyloxirane radical cations in freonic matrices at 77 K

Abstract

† CFCl 3 (Freon 11, ~99%, Aldrich) and CF3CCl3 (Freon 113a, obtained synthetically 5 from Freon 113, 99%, Aldrich; the main product constituted more than 99% of the mixture) were used; in certain cases, Freons were purified additionally by a standard procedure. 2,2-Dimethyloxirane (97%, Aldrich) was used as received. The dimethyloxirane/Freon solutions (0.3–0.5 mol%) were inserted into quartz or SK-4B glass tubes, evacuated to ~0.1 Pa and irradiated with X-rays at 77 K to doses of 2–4 kGy. A 5BHV6-W X-ray source (33 kV, 80 mA) was used. UV and EPR spectroscopy techniques were employed; the photochemical experiments and quantum chemical computations were performed as described earlier for the isomers of dimethyloxirane. 6