3384-35-8Relevant academic research and scientific papers
On the thermal unimolecular decomposition of the cyclohexoxy radical - An experimental and theoretical study
Welz, Oliver,Striebel, Frank,Olzmann, Matthias
, p. 320 - 329 (2008/09/18)
The kinetics of the thermal unimolecular decomposition of the cyclohexoxy radical (c-C6H11O) was experimentally studied, and the results were analyzed in terms of statistical rate theory with molecular and transition state data from quantum chemical calculations. Laser flash photolysis of cyclohexylnitrite at 351 nm was used to produce c-C6H 11O radicals, and their concentration was monitored by laser-induced fluorescence after excitation at 356.2 or 365.2 nm. The experiments were performed at temperatures ranging from 293 to 341 K and pressures between 5 and 55 bar with helium as the bath gas. Over the whole temperature range, biexponential profiles were observed, which is an indication of a consecutive reaction with a pre-equilibrium. From our quantum chemical calculations, it follows that this pre-equilibrium corresponds to the reversible ring-opening via β-C-C bond fission to form the 6-oxo-1-hexyl radical (l-C 6H11O), c-C6H11O -? l-C 6H11O (1,-1). The following temperature-dependent rate coefficients were deduced with an estimated uncertainty of ±30%: k 1(T) = 3.80 × 1013 exp(-50.1 kJ mol-1/RT) s-1 and k-1(T) = 3.02 × 108 exp(-23.8 kJ mol-1/RT) s-1; a pressure dependence was not observed. In our theoretical analysis, the different conformers of c-C6H 11O were explicitly taken into account, and the C-C torsional motions in l-C6H11O were treated as hindered internal rotators using a recently suggested approach. This explicit consideration of the hindered internal rotators significantly improved the agreement between the experimentally determined rate coefficients and the results from the quantum chemical computations. the Owner Societies.
Kinetics of the cross reactions of CH3O2 and C2H5O2 radicals with selected peroxy radicals
Villenave, Eric,Lesclaux, Robert
, p. 14372 - 14382 (2007/10/03)
The kinetics of the reactions of selected peroxy radicals (RO2) with CH3O2 and with C2H5O2 have been investigated using two techniques: excimer-laser photolysis and conventional flash photolysis, both coupled with UV absorption spectrometry. Radicals were generated either by photolysis of molecular chlorine in the presence of suitable hydrocarbons or by photolysis of the appropriate alkyl chloride. All such cross-reaction kinetics were investigated at 760 Torr total pressure and room temperature except for the reaction of the allylperoxy radical with CH3O2, for which the rate constant was determined between 291 and 423 K, resulting in the following rate expression: k15 = (2.8 ± 0.7) × 10-13 exp[(515 ± 75)/T] cm3 molecule-1 s-1. Values of (2.0 ± 0.5) × 10-13, (1.5 ± 0.5) × 10-12, (9.0 ± 0.15) × 10-14, -12, (2.5 ± 0.5) × 10-12, and (8.2 ± 0.6) × 10-12 (units of cm3 molecule-1 s-1) have been obtained for the reactions of CH3O2 radicals with C2H5O2, neo-C5H11O2, c-C6H11O2, C6H5CH2O2, CH2ClO2, and CH3C(O)O2, respectively, and (1.0 ± 0.3) × 10-12, (5.6 ± 0.8) × 10-13, (4.0 ± 0.2) × 10-14, and (1.0 ± 0.3) × 10-11 (units of cm3 molecule-1 s-1) for the reactions of C2H5O2 with CH2=CHCH2O2, neo-C5H11O2, c-C6H11O2, and CH3C(O)O2 radicals, respectively. These rate constants were obtained by numerical simulations of the complete reaction mechanisms, which were deduced from the known mechanisms of the corresponding peroxy radical self-reactions. A systematic analysis of propagation of errors was carried out for each reaction to quantify the sensitivity of the cross-reaction rate constant to the parameters used in kinetic simulations. The rate constant for a given cross reaction is generally found to be between the rate constants for the self-reactions of RO2 and CH3O2 (or C2H5O2). However, when the RO2 self-reaction is fast, the cross reaction with CH3O2 (or C2H5O2) is also fast, with similar rate constants for both reactions, suggesting that these particular peroxy radical cross reactions can play a significant role in the chemistry of hydrocarbon oxidation processes in the troposphere and in low-temperature combustion. Relationships between cross-reaction and self-reaction rate constants are suggested.
Generation and Chemistry of Cyclohexyloxy Radicals
Druliner, J. D.,Krusic, P. J.,Lehr, G. F.,Tolman, C. A.
, p. 5838 - 5845 (2007/10/02)
In this paper we report our work on cyclohexyloxy radicals from dicyclohexyl hyponitrite (CyON2OCy) and the related CyO sources dicyclohexyl peroxydicarbonate and dicyclohexyl peroxide (CyO2Cy), including the 13C and 1H NMR spectra of the radical sources, the kinetics of the DCHN decomposition over a wide range of temperature (followed by both UV and chemiluminescence), ESR spin-trapping studies, the kinetics of hydrogen atom abstraction from a variety of substrates by CyO, and the effect of CyO radical source on product composition.We have also investigated the effects of dissolved O2 on DCHN decomposition in cyclohexane and comment on the source of the observed chemiluminescence.
