Rate constants and kinetic deuterium isotope effects for hydrogen atom abstraction from phenols by polyvinyl acetate radical

1975 ◽  
pp. 252a-252a ◽  
Author(s):  
Miklós Simonyi ◽  
Ilona Fitos ◽  
Julianna Kardos ◽  
István Lukovits ◽  
Jan Pospišil
Keyword(s):  
Hydrogen Atom ◽  
Rate Constants ◽  
Polyvinyl Acetate ◽  
Isotope Effects ◽  
Hydrogen Atom Abstraction ◽  
Deuterium Isotope Effects

Absolute rate constants for hydrocarbon oxidation. VIII. The reactions of cumylperoxy radicals

1968 ◽  
Vol 46 (6) ◽  
pp. 1017-1022 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold ◽  
M. Symonds
Keyword(s):  
Rate Constants ◽  
Isotope Effects ◽  
Hydrogen Abstraction ◽  
Cumene Hydroperoxide ◽  
Hydrogen Atom Abstraction ◽  
Hydrocarbon Oxidation ◽  
Peroxy Radicals ◽  
Absolute Rate ◽  
Substituent Constants ◽  
Deuterium Isotope Effects

Absolute rate constants have been measured for the reactions of cumylperoxy radicals with a number of hydrocarbons. The cumylperoxy radicals were produced from cumene hydroperoxide. Sufficient hydroperoxide was present to ensure that only cumylperoxy radicals were involved in the rate-determining propagation reaction.Primary and secondary deuterium isotope effects have been measured for propagation and termination in the oxidation of cumene. The rate of hydrogen atom abstraction from ring-substituted cumenes by cumylperoxy radicals can be correlated by the Hammett equation using σ+ substituent constants, ρ = −0.29. Primary and secondary peroxy radicals are about 3–5 times more reactive in hydrogen abstraction than tertiary peroxy radicals.

Absolute Rate Constants for Hydrocarbon Autoxidation. Part XX. Oxidation of Some Organic Sulfides

1971 ◽  
Vol 49 (12) ◽  
pp. 2178-2182 ◽  
Author(s):  
J. A. Howard ◽  
S. Korcek
Keyword(s):  
Liquid Phase ◽  
Hydrogen Atom ◽  
Rate Constants ◽  
Hydrogen Atom Abstraction ◽  
Absolute Rate ◽  
Organic Sulfides

Absolute rate constants for the liquid phase autoxidation of some organic sulfides at 30 °C have been measured. The reactivities of organic sulfides towards t-butylperoxy radicals are equal to or somewhat less than the reactivities of structurally analogous ethers. The α-alkylthiylalkylperoxy radicals appear to be about 3–5 times more reactive in hydrogen atom abstraction than the α-alkoxyalkylperoxy radicals.

The kinetics, isotope effects, and mechanism of the reaction of 2,2-di(4-nitrophenyl)-1,1,1-trifluoroethane with alkoxide bases in alcohol solvents

1985 ◽  
Vol 63 (3) ◽  
pp. 576-580 ◽  
Author(s):  
Arnold Jarczewski ◽  
Grzegorz Schroeder ◽  
Wlodzimierz Galezowski ◽  
Kenneth T. Leffek ◽  
Urszula Maciejewska
Keyword(s):  
Rate Constants ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Tert Butanol ◽  
Deuterium Isotope Effects ◽  
Alcohol Solvents ◽  
Multistep Reaction ◽  
Mechanism Of The Reaction

The reaction between 2,2-di(4-nitrophenyl)-1,1,1-trifluoroethane and the alkoxide bases ŌCH3, ŌC2H5, ŌnC4H9, ŌCH(CH3)2, and ŌC(CH3)3 in their corresponding alcohol solvents is a multistep reaction with several intermediates: 2,2-di(4-nitrophenyl)-1,1-difluoro-1-alkoxyethane (A), 2,2-di(4-nitrophenyl)-1-fluoro-1-alkoxyethene (B), 2,2-di(4-nitrophenyl)-1,1-dialkoxyethene (C), 2,2-di(4-nitrophenyl)-1,1-difluoroethene (D), and 4,4′-dinitrobenzophene (E). Rate constants and activation parameters have been measured for the appearance of the two stable products B and C. The kinetic deuterium isotope effects for the appearance of B fell in the range of kH/kD = 1 to 2 at 25 °C for the primary and secondary alkoxides, whereas kH/kD = 5.4 at 30 °C for the appearance of D with tert-butoxide. Exchange experiments showed that H/D exchange took place between the substrate and solvent to the extent of 100% with methoxide, 50% with ethoxide and isopropoxide, and 0% with tert-butoxide. It is concluded the HF elimination from the substrate follows an (ElcB)R mechanism with methoxide/methanol, changing to (ElcB)I or E2 with tert-butoxide/tert-butanol.

Absolute rate constants for hydrocarbon autoxidation. VI. Alkyl aromatic and olefinic hydrocarbons

1967 ◽  
Vol 45 (8) ◽  
pp. 793-802 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Hydrogen Atom ◽  
Steric Hindrance ◽  
Rate Constants ◽  
Peroxy Radical ◽  
Electron System ◽  
Chain Termination ◽  
The Self ◽  
Hydrogen Atom Abstraction ◽  
Peroxy Radicals ◽  
Absolute Rate

Absolute rate constants have been measured for the autoxidation of a large number of hydrocarbons at 30 °C. The chain-propagating and chain-terminating rate constants depend on the structure of the hydrocarbon and also on the structure of the chain-carrying peroxy radical. With certain notable exceptions which are mainly due to steric hindrance, the rate constants for hydrogen-atom abstraction increase in the order primary < secondary < tertiary; and, for compounds losing a secondary hydrogen atom, the rate constants increase in the order unactivated < acyclic activated by a single π-electron system < cyclic activated by a single Π-system < acyclic activated by two π-systems < cyclic activated by two π-systems. The rate constants for chain termination by the self-reaction of two peroxy radicals generally increase in the order tertiary peroxy radicals < acyclic allylic secondary  [Formula: see text] cyclic secondary  [Formula: see text] acyclic benzylic secondary < primary peroxy radicals < hydroperoxy radicals.

A hydrogen-atom transfer mechanism in the oxidation of alcohols by [FeO4]2− in aqueous solution

2018 ◽  
Vol 47 (1) ◽  
pp. 240-245 ◽  
Author(s):  
Jianhui Xie ◽  
Po-Kam Lo ◽  
Chow-Shing Lam ◽  
Kai-Chung Lau ◽  
Tai-Chu Lau
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Atom ◽  
Dft Calculations ◽  
Isotope Effects ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Bond Dissociation Energies ◽  
Dissociation Energies ◽  
Oxidation Of Alcohols ◽  
Deuterium Isotope Effects

The oxidation of alcohols by [FeO4]2− in aqueous solution is found to proceed via a hydrogen atom transfer (HAT) mechanism based on deuterium isotope effects, correlation between rate constants and bond dissociation energies (BDEs) and DFT calculations.

Isotope effects on selective hydrogen atom abstraction by H atoms in λ-radiolysis and UV-photolysis of neopentane-alkane mixtures at 77 K

1980 ◽  
Vol 15 (4) ◽  
pp. 561-570 ◽  
Author(s):  
Tetsuo Miyazaki ◽  
Norio Goshima ◽  
Kenji Fueki ◽  
Yasuyuki Aratono ◽  
Enzo Tachikawa
Keyword(s):  
Hydrogen Atom ◽  
Isotope Effects ◽  
Hydrogen Atom Abstraction ◽  
Uv Photolysis
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