Fluoroaliphatic hydroxyketoradicals prepared by photochemicalreduction of the corresponding α-diketones and (i-C3F7)2C⋅C(O)CF3 react with hydrogen abstraction (according to ESR data). The hydroxyketoradicals are shown to dimerize reversibly, and the dimerization rate decreases in the presence of polyfluorinated alcohols due to the formation of radical–alcohol complexes.
Rate constants for the reactions of atomic oxygen (P-3) With selected alkanes (C-2-C-6 Straight chain alkanes, C-C6H12, neo-C5H12, and i-C4H10) have been determined directly by a laser photolysis-shock tube-atomic resonance absorption method at high temperatures (850-1250 K). For n-C6H14 and c-C6H12, rate constants have been also determined at lower temperatures (296-400 K) by a laser photolysis-vacuum ultraviolet laser-induced fluorescence method. Present results agree with the TST calculation by Cohen and Westberg [Int. J. Chem. Kinet. 1986, 18, 99] within experimental error limits except for O + c-C6H12 and O + neo-C5H12. The group additivity of the rate constants for different C-H bonds (primary, secondary, and tertiary) is examined and neo-C5H12 and c-C6H12 are found to be good representatives of primary and secondary C-H bonds, respectively, for C-4 and larger alkanes. A trial is made to investigate the J dependence of reactivity of atomic oxygen (P-3(J)) With c-C6H12 to examine the adiabatic correlation of reactants and products. No evidence for such J dependence can be observed due to the rapid relaxation among the spin-orbit components. Rate constants for the intratriplet relaxation processes are evaluated for He as a collision partner.
Tilman, P.; Tilquin, B.; Claes, P., Journal de Chimie Physique et de Physico-Chimie Biologique, 1982, vol. 79, # 9, p. 629 - 632
作者:Tilman, P.、Tilquin, B.、Claes, P.
DOI:——
日期:——
Paramagnetic relaxation of alkyl radicals in solid alkanes as studied by electron spin echo method: possibility of high-resolution solid-state ESR