Direct Detection of Hydroxy‐Cyclohexadienyl in the Gas Phase by cw‐UV‐Laser Absorption

Fritz, B.; Handwerk, V.; Preidel, M.; Zellner, R.

doi:10.1002/bbpc.19850890347

Cited by 17 publications

(14 citation statements)

References 8 publications

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“…However, a value of σ(HO-C 6 H 6 ) ) (9.2 ( 2) × 10 -18 cm 2 molecule -1 at 308.3 nm has been obtained by flash photolysis combined with detection of OH and HO-C 6 H 6 with a frequency-doubled ring dye laser with a spectral resolution on the order of 10 -6 nm. 28 Thus, although the low-resolution spectrum of HO-C 6 H 6 shown in Figure 3 does not show any significant fine structure, it seems likely that a high-resolution spectrum may exhibit a dense vibronic structure at wavelengths above 300 nm. Our experimental results on OH-kinetics also show that σ(HOC 6 H 6 ) , σ(OH) at (309.04 ( 0.08) nm.…”

Section: Uv Spectrum and Kinetics Of Hydroxycyclohexadienyl Radicalsmentioning

confidence: 89%

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UV Spectrum and Kinetics of Hydroxycyclohexadienyl Radicals

Bjergbakke¹,

Sillesen²,

Pagsberg³

1996

J. Phys. Chem.

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High yields of H-atoms and OH-radicals were produced by pulse radiolysis of Ar/H2O mixtures, and in the presence of C6H6, the addition reactions (1a) OH + C6H6 → HO−C6H6 and (2) H + C6H6 → H−C6H6 have been studied by transient ultraviolet absorption spectroscopy of the short-lived radicals OH, HO−C6H6, and H−C6H6. The ultraviolet absorption spectra of HO−C6H6 and H−C6H6 have been recorded in the range 250−350 nm with a maximum value of σ(HO−C6H6) = (4.6 ± 0.7) × 10-18 cm2 molecule-1 observed at 280 nm. Studies of OH-decay and the simultaneous formation of HO−C6H6 have been used to determine an overall rate constant of k(OH + C6H6) = (1.2 ± 0.2) × 10-12 cm3 molecule-1 s-1 at T = 298 K. Phenol was identified as a primary product with a relative yield of 25 ± 5% derived from the amplitude of the strong absorption band at 275 nm. Different reaction mechanisms have been considered, but only the direct displacement reaction (1b) OH + C6H6 → H + C6H5OH seems to account for the experimental results. The kinetics of the reaction (3) HO−C6H6 + NO2 → products has been studied, and a rate constant of (1.1 ± 0.2) × 10-11 cm3 molecule-1 s-1 has been determined at T = 338 K. Attempts to identify the reaction products by UV spectroscopy were unsuccessful. Transient absorption signals observed in the presence of oxygen have been assigned to peroxy radicals produced in the reaction HO−C6H6 + O2 → HO−C6H6-O2. A rate constant of (5.0 ± 1.0) × 10-13 cm3 molecule-1 s-1 has been derived from the observed formation kinetics.

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Section: Uv Spectrum and Kinetics Of Hydroxycyclohexadienyl Radicalsmentioning

confidence: 89%

“…Previously, this technique has been employed by Zellner et al using a frequency-doubled ring dye laser for the detection of OH at 308.419 nm as well as HO-C 6 H 6 at 308.3 nm. 28 Recently, this technique has also been employed in studies of the reaction HO-C 6 H 6 + O 2 f products. 30 3.3.…”

Section: Uv Spectrum and Kinetics Of Hydroxycyclohexadienyl Radicalsmentioning

confidence: 99%

UV Spectrum and Kinetics of Hydroxycyclohexadienyl Radicals

Bjergbakke¹,

Sillesen²,

Pagsberg³

1996

J. Phys. Chem.

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“…This reaction leads solely to the ipso isomer, although other reaction products, including displacement of OH for H leading directly to phenol, have also been postulated to be competitive with OH-addition. 26,30 Previous calculations of the stability of the ipso isomer lie in the range −66 to −78 kJ mol −1 relative to phenol + H with an entrance channel barrier of 26 to 41 kJ mol −1 . [27][28][29] The energies of the other isomers have been calculated by Sander et al 27 Their hydroxy-CHD energies are slightly lower with respect to phenol + H than ours, but were not corrected for zpe.…”

Section: Discussionmentioning

confidence: 99%

Hydrogen-atom attack on phenol and toluene is ortho-directed

Krechkivska

Wilcox

Troy

et al. 2016

Phys. Chem. Chem. Phys.

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The reaction of H + phenol and H/D + toluene has been studied in a supersonic expansion after electric discharge. The (1 + 1') resonance-enhanced multiphoton ionization (REMPI) spectra of the reaction products, at m/z = parent + 1, or parent + 2 amu, were measured by scanning the first (resonance) laser. The resulting spectra are highly structured. Ionization energies were measured by scanning the second (ionization) laser, while the first laser was tuned to a specific transition. Theoretical calculations, benchmarked to the well-studied H + benzene → cyclohexadienyl radical reaction, were performed. The spectrum arising from the reaction of H + phenol is attributed solely to the ortho-hydroxy-cyclohexadienyl radical, which was found in two conformers (syn and anti). Similarly, the reaction of H/D + toluene formed solely the ortho isomer. The preference for the ortho isomer at 100-200 K in the molecular beam is attributed to kinetic, not thermodynamic effects, caused by an entrance channel barrier that is ∼5 kJ mol(-1) lower for ortho than for other isomers. Based on these results, we predict that the reaction of H + phenol and H + toluene should still favour the ortho isomer under elevated temperature conditions in the early stages of combustion (200-400 °C).

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“…The reaction of OH radicals with aromatic hydrocarbons containing side chains have been studied [20,21,23,24,[26][27][28][29][30][31][32] with the result that the reaction rates are in the range 9.2.10'' I k/cm3/(mol. s) 5 3.8 .…”

Section: Discussionmentioning

confidence: 99%

Elementary reactions of fluorine atoms with benzene, toluene, p‐xylene and etylbenzene

Ebrecht¹,

Hack²,

Wagner³

1989

Ber Bunsenges Phys Chem

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The rate constants of the reactions of fluorine atoms with benzene, toluene, p‐xylene and ethylbenzene were studied in a discharge flow reactor at room temperature and low pressure. — The aromatic compounds R were followed under pseudo first order conditions ([R]0 ≪ [F]) by mass spectrometry (MS). The rate constants. F + C6H6 k1 (296 K) = (3.0 ± 0.7). 1013 cm3/mol·s (1). F + C6H5CH3 k2 (296 K) = (4.0 ± 0.8). 1013 cm3/mol·s (2). F + C6H4(CH3)2 k3 (296 K) = (4.2 ± 0.6). 1013 cm3/mol·s (3). F + C6H5C2H5 k4 (296 K) = (4.5 ± 0.6). 1013 cm3/mol·s (4). were obtained. — The products of reaction (1) were C6H5F (80%) and HF (< 8%) and those of reaction (2) were C‐H‐F (50%), C6H5F (20%) and HF (20%). For reaction (3) the exchange mechanism is dominant, C7H7F, C8H9F (65%), and the abstraction contributes 35% (HF). In reaction (4) the abstraction is dominant (HF (50%)) with an exchange pathway of 50% C6H5F and C8H9F.

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Direct Detection of Hydroxy‐Cyclohexadienyl in the Gas Phase by cw‐UV‐Laser Absorption

Cited by 17 publications

References 8 publications

UV Spectrum and Kinetics of Hydroxycyclohexadienyl Radicals

UV Spectrum and Kinetics of Hydroxycyclohexadienyl Radicals

Hydrogen-atom attack on phenol and toluene is ortho-directed

Elementary reactions of fluorine atoms with benzene, toluene, p‐xylene and etylbenzene

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