2143-61-5Relevant articles and documents
Homolytic dissociation of 1-substituted cyclohexa-2,5-diene-1-carboxylic acids: An EPR spectroscopic study of chain propagation
Jackson, Leon V.,Walton, John C.
, p. 1758 - 1764 (2007/10/03)
Hydrogen abstraction from 1-substituted cyclohexa-2,5-diene-1-carboxylic acids containing linear, branched and cyclic alkyl substituents, as well as allyl, propargyl (prop-2-ynyl), cyanomethyl and benzyl substituents, has been studied by EPR spectroscopy. For each carboxylic acid, EPR spectra of the corresponding cyclohexadienyl radicals were observed at lower temperatures, followed by spectra due to ejected carbon-centred radicals at higher temperatures. Rate constants, for release of the carbon-centred radicals from the cyclohexadienyl radicals, were determined from radical concentration measurements for the above range of substituents. The rate of cyclohexadienyl radical dissociation increased with branching in the 1-alkyl substituent and with electron delocalisation in the ejected carbon-centred radical; 3,5-and 2,6-dimethyl-substitution of the cyclohexadienyl ring led to reductions in the dissociation rate constants. Rate data for abstraction of bisallylic hydrogens from the cyclohexadienyl acids were also obtained for ethyl, n-propyl and isopropyl radicals. These results indicated a sharp drop in the rate of hydrogen abstraction as the degree of branching in the attacking radical increased. Small decreases in the hydrogen abstraction rate constants were observed for cyclohexadienes containing CO2R substituents.
Kinetics and mechanisms of the reactions of chlorine atoms with ethane, propane, and n-butane
Tyndall,Orlando,Wallington,Dill,Kaiser
, p. 43 - 55 (2007/10/03)
Absolute (flash photolysis) and relative (FTIR-smog and GC) rate techniques were used to study the gas-phase reactions of Cl atoms with ethane (k1), propane (k3), and n-butane (k2). Experiments performed at 298-540 K give k2÷k1=(2.0±0.1)exp((183±20)÷T). At 296 K the reaction of Cl atoms with propane yields of 43 % 1-propyl and 57 % 2-propyl radicals, while the reaction of Cl atoms with n-butane produces 29% 1-butyl and 71% 2-butyl radicals. Butyl radicals were found to react with Cl2 with rates which are 3 times greater than the corresponding reactions with O2.
Kinetics of the Reactions of the CF3O Radical with Alkanes
Barone, Stephen B.,Turnipseed, Andrew A.,Ravishankara, A. R.
, p. 4602 - 4608 (2007/10/02)
Utilizing the technique of pulsed laser photolysis/pulsed laser induced fluorescence, we have investigated the atmospherically important reactions of the (trifluoromethyl)peroxy radical, CF3O, with several alkanes.The reaction rate coefficients for CF3O + CH4 (k3), C2H6 (k4), C3H8 (k5), (CH3)3CH (k6), and CD4 (k7) were measured, as functions of temperature, to be k3 = (1.92 +/- 0.33) x E-12 exp cm3 molecule-1 s-1, k4 = (4.84 +/- 1.11) x E-12 exp cm3 molecule-1 s-1, k5 = (5.12 +/- 1.12) x E-12 exp cm3 molecule-1 s-1, k6 = (4.32 +/- 0.42) x E-12 exp cm3 molecule-1 s-1, and k7 = (0.91 +/- 0.31) E-12 exp cm3 molecule-1 s-1, respectively.These kinetic data are compared with results from previous studies.The atmospheric implications of these findings are discussed.
