23201-84-5Relevant academic research and scientific papers
Electron Spin Resonance Study of Azoalkane and Imine Radical Cations
Rhodes, Christopher J.
, p. 3215 - 3222 (2007/10/02)
Radical cations of azoalkanes have been observed for the first time in low-temperature matrix by e.s.r. spectroscopy.The e.s.r. data show that they are ?-cations despite photoelectron studies which indicate the HOMO for an azoalkane to be the ? (n-) orbital.Interestingly, these species appear to be stable, at least up to ca. 160 K, and show no tendency to fragment to form alkyl radicals.This contrasts with the solution-phase behaviour of these species, which are intermediates in the oxidation of azoalkanes, and give rise to carbocations and alkyl radicals.Imines form similar ?-radical cations which show a greater tendency to decompose.The structures and stabilities of these cations are discussed.Attempts to observe the corresponding azoalkane anions in solid matrices resulted only in the formation of alkyl radicals, and so we conclude that the anions decompose by fragmentation, although they have been studied in solution under steady-state conditions.Previously derived coupling parameters predict isotropic 14N hyperfine couplings for these species which are larger than those observed.Therefore, new values are calculated, and these fit well with the observed couplings.In this way, spin polarisation parameters are obtained for individual contributions to the couplings, as opposed to previous approaches which treat them collectively.
Reactions of Alkylperoxyl Radicals in Solution. Part 1. A Kinetic and Product Study of Self-reactions of 2-Propylperoxyl Radicals between 253 and 323 K
Bennett, John E.,Brunton, George,Schmith, Lindsay John R.,Salmon, Tom M. F.,Waddington, David J.
, p. 2433 - 2448 (2007/10/02)
The self-reactions of 2-propylperoxyl radicals have been studied between 253 and 323 K in decane solution.The ratio of the major products, propanone and propan-2-ol, as a function of temperature is in good agreement with the behaviour of other secondary peroxyl radicals in solution.The roles played by the solvent are considered by comparison with pervious studies of this radical in the gas phase.It is concluded that the increase in ketone production relative to the alcohol as the temperature is lowered is best explained by the inclusion of the bimolecular reaction of the peroxyl radical producing propanone and hydrogen peroxide.It is suggested that this reaction has Arrhenius parameters of A ca.E+6 dm3 mol-1 s-1 and Ea ca. 5 kJ mol-1.
REACTIONS OF OXYGENATED RADICALS IN THE GAS PHASE. PART 16. DECOMPOSITION OF ISOPROPOXYL RADICALS
Akeel, Najah Y. Al,Waddington, David J.
, p. 1575 - 1580 (2007/10/02)
The photo-oxidation of trans-2,2'-azopropane has been studied between 333 and 434 K.The main products are propan-2-ol, isopropyl hydroperoxide, and acetone.Acetaldehyde becomes an increasingly important product as the temperature and pressure are increased.By altering the total pressure of the system, using nitrogen as diluent, quantitative data for the rate of decomposition of isopropoxyl radicals may be obtained. k11 varies markedly with pressure between 20 and 760 Torr in this temperature regime. .
Reactions of Oxigenated Radicals in the Gas Phase
Cowley, Leslie T.,Waddington, David J.,Woolley, Allan
, p. 2535 - 2546 (2007/10/02)
The principal product of the photo-oxidation of trans-2,2'-azopropane between 333 and 373 K are acetone, isopropyl alcohol, isopropyl hydroperoxide, acetaldehyde, formaldehyde, methyl alcohol and cis-2,2'-azopropane.The reaction mechanism has been simulated in detail, and, in conjunction with results obtained earlier for the overall self-reaction of isopropylperoxy radicals, the following rate data have been obtained for the reactions 2(CH3)2CHO2. --> (CH3)2CHOH + (CH3)2CO + O2 (3a) 2(CH3)2CHO2. --> 2(CH3)2CHO. + O2 (3b) k3b/k3a increases with temperature, from 1.39 +/-0.04 at 302 K and 2.80 +/- 0.08 at 373 K.Values of A3a and A3b of 2.44 +/- 0.31E7 and 1.38 +/-0.26E9 dm3 mol-1 s-1 and E3a and E3b of 12.0 +/- 1.0 and 21.3 +/- 1.5 kJ mol-1 were determined.
Reactions of Oxygenated Radicals in the Gas Phase. Part 11. Reaction of Isopropylperoxyl Radicals with 2,3-Dimethylbut-2-ene
Sway, Mohammed I.,Waddington, David J.
, p. 999 - 1004 (2007/10/02)
The reaction of isopropylperoxyl radicals with 2,3-dimethylbut-2-ene has been studied between 303 and 363 K, using the photo-oxidation of trans-2,2'-azopropane as a source of the radicals.The only product formed from the alkene is 2,3-dimethyl-2,3-epoxybutane.From a detailed study of the products, Arrhenius parameters for reaction (22) of log (A/dm3 mol-1s-1) = 7.96 +/- 0.50 and E/kJ mol-1 = 40.87 +/- 1.78 have been obtained.
