Chapter 2 Metathetical Reactions of Atoms and Radicals

Kerr, J. A.

doi:10.1016/s0069-8040(08)70122-5

Cited by 8 publications

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“…For a series of the H + R−H → H 2 + R gas-phase reactions, where R is an alkyl, a much smaller slope, a = 0.38, is observed. 19 Mechanistically, slopes above and below 0.5 are commonly interpreted as the indication of the product-like and reactant-like transition states, respectively. If valid, this comparison suggests the change from an early to a late transition state upon hydration.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…This equation is equivalent to the Polanyi activation energy correlation: E a = a Δ H + constant. For a series of the H + R–H → H 2 + R gas-phase reactions, where R is an alkyl, a much smaller slope, a = 0.38, is observed . Mechanistically, slopes above and below 0.5 are commonly interpreted as the indication of the product-like and reactant-like transition states, respectively.…”

Section: Resultsmentioning

confidence: 99%

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Hydrogen Atom Reactivity toward Aqueous tert-Butyl Alcohol

Lymar

Schwarz

2012

J. Phys. Chem. A

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Through a combination of pulse radiolysis, purification, and analysis techniques, the rate constant for the H + (CH(3))(3)COH → H(2) + (•)CH(2)C(CH(3))(2)OH reaction in aqueous solution is definitively determined to be (1.0 ± 0.15) × 10(5) M(-1) s(-1), which is about half of the tabulated number and 10 times lower than the more recently suggested revision. Our value fits on the Polanyi-type, rate-enthalpy linear correlation ln(k/n) = (0.80 ± 0.05)ΔH + (3.2 ± 0.8) that is found for the analogous reactions of other aqueous aliphatic alcohols with n equivalent abstractable H atoms. The existence of such a correlation and its large slope are interpreted as an indication of the mechanistic similarity of the H atom abstraction from α- and β-carbon atoms in alcohols occurring through the late, product-like transition state. tert-Butyl alcohol is commonly contaminated by much more reactive secondary and primary alcohols (2-propanol, 2-butanol, ethanol, and methanol), whose content can be sufficient for nearly quantitative scavenging of the H atoms, skewing the H atom reactivity pattern, and explaining the disparity of the literature data on the H + (CH(3))(3)COH rate constant. The ubiquitous use of tert-butyl alcohol in pulse radiolysis for investigating H atom reactivity and the results of this work suggest that many other previously reported rate constants for the H atom, particularly the smaller ones, may be in jeopardy.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Hydrogen Atom Reactivity toward Aqueous tert-Butyl Alcohol

Lymar

Schwarz

2012

J. Phys. Chem. A

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Vertical distribution of disequilibrium species in Jupiter's troposphere

Lewis

Fegley

1984

Space Sci Rev

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Sources of organic matter and inorganic tracers on Jupiter, including solar UV pbotolysis, lightning discharges, and convective quenching of hot gases from the lower atmosphere, are reviewed in light of Earth-based and Voyager data with the purpose of predicting the tropospheric steady-state abundances and vertical distributions of HCN, CH20 , and other species.It is concluded that a steady-state mole fraction of HCN in the Jovian troposphere of only ~ 10-a2 could be maintained by vertical transport of hot gases from the deep atmosphere. The observed HCN abundance (roughly Xnc N = 10-9) appears to be due to photochemical reactions.After HCN, the most abundant organic disequilibrium species in the troposphere is probably C2H6, derived from direct photolysis of CH 4 at high altitudes, with a mole fracton of ~ 10-1o at the H20 cloud level. Inorganic tracers of disequilibrium processes are also briefly summarized.

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