Reactions of HCCCO and NCCO radicals with O 2 have been studied by a combination of pulsed laser photolysis and photoionization mass spectrometry. HCCCO was produced by 193-nm photolysis of methylpropiolate or 3-butyn-2-one, and NCCO was formed by 193-nm photolysis of acetylcyanide. The rate constan
Pressure dependence of phenylperoxy radical formation in the reaction of phenyl radical with molecular oxygen
β Scribed by K. Tanaka; M. Ando; Y. Sakamoto; K. Tonokura
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 301 KB
- Volume
- 44
- Category
- Article
- ISSN
- 0538-8066
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β¦ Synopsis
Pressure dependence of the phenylperoxy radical (C 6 H 5 O 2 ) formation in the reaction of phenyl radical (C 6 H 5 ) with molecular oxygen (O 2 ) has been investigated with the cavity ring-down method by detecting the C 6 H 5 O 2 at 504 nm. The rate constant of the C 6 H 5 + O 2 reaction was determined to be k = (1.2 Β± 0.1) Γ 10 -11 cm 3 molecule -1 s -1 by the least-square analysis of several sets of the C 6 H 5 O 2 rise profiles at 30 Torr and at 296 K. This value is almost identical to those previously obtained at 40 Torr (Yu and Lin, J Am Chem Soc 1994, 98, 9571-9576) and 760 Torr (Tonokura et al., J Phys Chem A 2002, 106, 5908-5917), indicating that the rate constant has no pressure dependence in the pressure range of 30-760 Torr. The signal intensity ratio of C 6 H 5 O 2 to C 6 H 5 was obtained in the pressure range of 5-120 Torr. Varying the third body carrier gas (N 2 ) had a significant effect on the production of the C 6 H 5 O 2 . To validate the k determination by C 6 H 5 O 2 rise detection and determine the branching ratio of C 6 H 5 O 2 in the C 6 H 5 + O 2 reaction system, theoretical calculations were also performed. The rate constant obtained with Rice-Ramsperger-Kassel-Marcus/master equation calculations is in good agreement with that measured in this experiment. The branching ratio forming C 6 H 5 O 2 obtained by the theoretical calculation also exhibited pressure dependence, which is consistent with the experimental results. The branching ratio increases with increasing pressure and reaches approximately 0.85 at 120 Torr.
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