Disproportionation-Combination Reactions of Alkyl Radicals and Hydrogen Atoms at Low Temperatures

Klein, Ralph; Scheer, Milton D.; Kelley, R. D.

doi:10.1021/j100785a027

Cited by 21 publications

(16 citation statements)

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“…Reactions of gas phase atomic hydrogen with solid olefins at low temperatures (<150 K) have also been investigated, and hydrogen addition to the double bond to form an alkyl radical is the primary process observed. − The alkyl radicals produced either react with other alkyl radicals or react with hydrogen atoms depending on the mobility of alkyl radicals in the solid …”

Section: Introductionmentioning

confidence: 99%

“…For instance, undiluted solid 1-hexene does not appear to react with atomic hydrogen at 77 K but shows considerable reactivity when diluted with inerts which enhance mobility . The estimated activation energy for hydrogen atom addition to solid olefins is approximately 1.5 kcal/mol …”

Section: Introductionmentioning

confidence: 99%

“…1 Reactions of gas phase atomic hydrogen with solid olefins at low temperatures (<150 K) have also been investigated, and hydrogen addition to the double bond to form an alkyl radical is the primary process observed. [2][3][4][5] The alkyl radicals produced either react with other alkyl radicals or react with hydrogen atoms depending on the mobility of alkyl radicals in the solid. 5 Reactions between alkyl radicals predominate in solids where diffusion of alkyl radicals is rapid, while reactions with atomic hydrogen dominate when high-viscosity matrices are employed.…”

Section: Introductionmentioning

confidence: 99%

“…5 The estimated activation energy for hydrogen atom addition to solid olefins is approximately 1.5 kcal/mol. 3 Disproportionation of the alkyl radicals produced appears to proceed without activation energy.…”

Section: Introductionmentioning

confidence: 99%

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Gas Phase Atomic Hydrogen-Induced Hydrogenation of Cyclohexene on the Ni(100) Surface

Son

Gland

1997

J. Phys. Chem. B

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Gas phase hydrogen atoms add to adsorbed cyclohexene at 100 K on the Ni(100) surface, resulting in cyclohexane formation during subsequent TPR (temperature-programmed reaction) experiments. No C-C bond activation is observed after exposure to gas phase atomic hydrogen. Vibrational and isotope studies indicate that a cyclohexyl intermediate is formed by the addition of gas phase atomic hydrogen to adsorbed cyclohexene. This adsorbed cyclohexyl is hydrogenated primarily by surface hydrogen to form cyclohexane during subsequent heating. Cyclohexane yields increase with increasing atomic hydrogen exposure, and yields in the 90% range have been observed with large atomic hydrogen exposures. In the presence of only coadsorbed hydrogen, no significant hydrogen addition to adsorbed cyclohexene is observed, and cyclohexene desorption dominates during subsequent TPR experiments. Vibrational spectroscopy indicates that π-bonded cyclohexene with the CdC bond parallel to the surface is the dominant surface species in the presence of coadsorbed surface hydrogen. In contrast, di-σ-bonded cyclohexene is the dominant species in the absence of coadsorbed hydrogen. In the absence of coadsorbed hydrogen, dehydrogenation of the adsorbed cyclohexene results in benzene formation with increasing temperature. Adsorbed benzene formed by dehydrogenation has been identified after heating to 390 K in the absence of hydrogen using vibrational spectroscopy.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Gas Phase Atomic Hydrogen-Induced Hydrogenation of Cyclohexene on the Ni(100) Surface

Son

Gland

1997

J. Phys. Chem. B

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“…Falconer & Burton, bearing in mind that G(H2) does not change much with LET, conclude that reaction 13 is the most probable reaction occurring in the spurs and tracks, with a yield of about 1 molecule per 100 eV. Independent studies of reaction 13 are not available, but Klein, Scheer & Kelley (136) have found that disproportionation predominates over combination for the reaction of hydrogen atoms with sec butyl radicals at 90° K, in agreement with reaction 13.…”

Section: Free Radical Processesmentioning

confidence: 80%

Radiation Chemistry

Schwarz¹

1965

Annu. Rev. Phys. Chem.

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The photolysis of 2‐fluorocyclohexanone in the 313‐nm region. The elimination of hydrogen fluoride from vibrationally excited fluorocyclopentane

Pritchard

Gute

1978

Int J of Chemical Kinetics

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The gas-phase photolysis of 2-fluorocyclohexanone at 313 nm and 120°C is reported. The primary dissociative step appears to be The 1-fluoropentanediyl species can disproportionate to form the 1-and 5-fluoro-l-pentenes, or cyclize to form vibrationally excited fluorocyclopentane. The latter molecule either undergoes collisional stabilization or decomposes unimolecularly to give cyclopentene and HF. The half-quenching pressure for the latter reaction was 2 torr. The disproportionation-to-combination ratio for the diradical was found to be 1.2. Some brief preliminary experiments on the liquid-phase photolysis of 2-chlorocyclohexanone and 8-fluorocyclohexanone are also described.

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Disproportionation-Combination Reactions of Alkyl Radicals and Hydrogen Atoms at Low Temperatures

Cited by 21 publications

References 0 publications

Gas Phase Atomic Hydrogen-Induced Hydrogenation of Cyclohexene on the Ni(100) Surface

Gas Phase Atomic Hydrogen-Induced Hydrogenation of Cyclohexene on the Ni(100) Surface

Radiation Chemistry

The photolysis of 2‐fluorocyclohexanone in the 313‐nm region. The elimination of hydrogen fluoride from vibrationally excited fluorocyclopentane

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