34207-39-1Relevant articles and documents
REACTION OF PHENOXY RADICAL WITH NITRIC OXIDE
Yu, T.,Mebel, A. M.,Lin, M. C.
, p. 47 - 53 (1995)
The association of C6H5O with NO was studied with the cavity-ring-down method by directly monitoring the decay of C6H5O in the presence of varying, excess amounts of NO.The bimolecular rate constant determined in the temperature range 297-373 K can be effectively represented by k1=10-12.12+/-0.24e(194+/-185)/T cm3 molecule-1 with a negative activation energy of 0.8 kcal mol-1 (1 kcal=4.184 kJ).In order to understand better the mechanism of the reaction, ab initio molecular orbital calculations were also carried out at the MP4(SDQ)/6-31G* level of theory using the HF optimized geometries.The molecular structures and energetics of five C6H5N1O2 isomers were calculated.Among them, the most likely and stable association product, phenyl nitrite (C6H5ONO), was found to be 17 kcal mol-1 below the reactants, C6H5O+NO.Combining the measured rate constant and the calculated equilibrium constant for the association reaction, C6H5O+NO=C6H5ONO the rate constant for the unimolecular decomposition of C6H5ONO was obtained as k-1=4.6*1015E-8580/T s-1.The relatively large frequency factor suggests that a loose transition state was involved in the reaction, akin to those of its alkyl analogs (RONO, R=CH3, C2H5, etc.).
Atmospheric chemistry of the phenoxy radical, C6H5O(?): UV spectrum and kinetics of its reaction with NO, NO2, and O2
Platz,Nielsen,Wallington,Ball,Hurley,Straccia,Schneider,Sehested
, p. 7964 - 7974 (2007/10/03)
Pulse radiolysis and FT-IR smog chamber experiments were used to investigate the atmospheric fate of C6H5O(?) radicals. Pulse radiolysis experiments gave σ(C6H5O(?))235 nm = (3.82 ± 0.48) × 10-17 cm2 molecule-1, k(C6H5O(?) + NO) = (1.88 ± 0.16) × 10-12, and k(C6H5O(?) + NO2) = (2.08 ± 0.15) × 10-12 cm3 molecule-1 s-1 at 296 K in 1000 mbar of SF6 diluent. No discernible reaction of C6H5O(?) radicals with O2 was observed in smog chamber experiments, and we derive an upper limit of k(C6H5O(?) + O2) -21 cm3 molecule-1 s-1 at 296 K. These results imply that the atmospheric fate of phenoxy radicals in urban air masses is reaction with NOx. Density functional calculations and gas chromatography-mass spectrometry are used to identify 4-phenoxyphenol as the major product of the self-reaction of C6H5O(?) radicals. As part of this study, relative rate techniques were used to measure rate constants for reaction of Cl atoms with phenol [k(Cl + C6H5OH) = (1.93 ± 0.36) × 10-10], several chlorophenols [k(Cl + 2-chlorophenol) = (7.32 ± 1.30) × 10-12, k(Cl + 3-chlorophenol) = (1.56 ± 0.21) × 10-10, and k(Cl + 4-chlorophenol) = (2.37 ± 0.30) × 10-10], and benzoquinone [k(Cl + benzoquinone) = (1.94 ± 0.35) × 10-10], all in units of cm3 molecule-1 s-1. A reaction between molecular chlorine and C6H5OH to produce 2- and 4-chlorophenol in yields of (28 ± 3)% and (75 ± 4)% was observed. This reaction is probably heterogeneous in nature, and an upper limit of k(Cl2 + C6H5OH) ≤ 1.9 × 10-20 cm3 molecule-1 s-1 was established for the homogeneous component. These results are discussed with respect to the previous literature data and to the atmospheric chemistry of aromatic compounds.
Cw laser absorption study of the reactions of phenyl radicals with NO, NO2, O2 and selected organics between 298-404 K
Preidel,Zellner
, p. 1417 - 1423 (2007/10/02)
The applied aspect concerning the reactivity of phenyl relates to its suggested participation in the formation mechanisms of polycyclic aromatic hydrocarbons (PAHs) and of soot. In the present paper we report the first application of a direct detection method of phenyl in the gas phase. It will be shown that by using the 488 nm laser line absorption in the $UNK2A1 - $UNK2B1 transition phenyl can be detected with sufficient sensitivity to enable kinetic investigations of its reactions. To our knowledge this has not been achieved before. Rate constant for the reactions of phenyl (C6H5) radicals with NO, NO2, O2, C2H4, 2-butene, benzene, toluene and CCl4 have been determined using a combined laser photolysis laser absorption technique. Phenyl radicals were generated by 248 nm excimer laser photolysis of C6H5X, where X = Cl, Br and NO. Their temporal behaviour was monitored using cw-laser line absorption in the $UNK2A1 - $UNK2B1 transition at 488 nm. The magnitude of the rate coefficients k1 and k2 and their negative temperature dependence suggest that the reactions between phenyl and NO/NO2 occur as radical recombination and/or (in the case of NO2) as O-atom metathesis reaction. The apparent low reactivity of phenyl with O2 is likely to be caused by insufficient thermal stability of the phenylperoxi radical.
