UV absorption spectra and self-reaction rate constants for primary peroxy radicals arising from the chlorine-initiated oxidation of carbonyl compounds

A flash photolysis setup coupled to UV absorption spectrometry detection was used to measure the UV absorption spectra of the (CH3)(2)(CH2O2.)CC(O)C(CH3)(3) and (CH3)(2)(CH2O2.)CC(O)CH3 radicals between 207 and 290 nm. The self-reaction rate constants of these radicals were measured at 298 K: k((CH3)(2)(CH2O2.)CC(O)C(CH3)(3)+ (CH3)(2)(CH2O2.)CC(O)C(CH3)(3)) = (4.57 +/- 0.38) x 10(-12) cm(3) molecule(-1)s(-1);k((CH3)(2)(CH2O2.) CC(O)CH3 + (CH3)(2)(CH2O2.)CC(C))CH3) = (4.77 +/- 0.35) x 10(-12) cm(3) molecule(-1) s(-1), where quoted uncertainties only represent 2 sigma errors. Because of the similarities in both UV spectra and self-reaction kinetics between (CH3)(2)(CH2O2.)CC(O)C(CH3)(3) and (CH3)(2)(CH2O2.)CC(O)CH3 radicals, it was suggested to extend this results to all (CH3)(2)(CH2O2.)CC(O)R peroxy radicals (with R = H, alkyl), arising from the chlorine-initiated oxidation of carbonyl compounds. This trend has been tested successfully in the case of the Cl-initiated oxidation of pivalaldehyde (Le Crane et al, J Phys Chem A 2004, 108, 795). (c) 2006 Wiley Periodicals, Inc.