The optical and ESR spectra of the trapped intermediates produced by γ irradiation of the cyclic thioether 2-methyltetrahydrothiophene (MTHT) in the glassy state at 77 K have been investigated for the purpose of comparing the radiation chemistry of MTHT with that of the much studied oxygen analogue 2-methyltetrahydrofuran (MTHF). The MTHT, in contrast to MTHF, does not physically trap electrons. The electrons react with the MTHT producing a product or products, with a broad absorption at 460 nm, assigned to paramagnetic anions such as CH3CH2CH2CH2ĊHS- or CH3CH2CH2Ċ(CH3)S-. A band centered at 625 nm, which is reduced by positive charge scavengers, is attributed to the cation radical of MTHT. Both the ESR and optical spectra show selective bleaching effects with near-ultraviolet and visible light. The products of γ radiolysis of solutions of 10% of MTHT in MTHF glass reveal both the electron scavenging ability of MTHT and positive charge stabilization by MTHF. Photolysis of MTHT glass at 254 nm produces thiyl radicals. Photoionization of tetramethyl-p-phenylenediamine (TMPD) in MTHT glass is accompanied by formation of MTHT radicals.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry