Rate constants for chain termination in oxidized cyclohexylamine, di-n-butylamine, cyclohexanol, and cyclohexyl methyl ether

1974 ◽  
Vol 23 (11) ◽  
pp. 2546-2548
Author(s):  
G. A. Kovtun ◽  
A. V. Kazantsev ◽  
A. L. Aleksandrov
Keyword(s):  
Methyl Ether ◽  
Rate Constants ◽  
Chain Termination ◽  
Cyclohexyl Methyl

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.

Absolute rate constants for hydrocarbon autoxidation. V. The hydroperoxy radical in chain propagation and termination

1967 ◽  
Vol 45 (8) ◽  
pp. 785-792 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Rate Constants ◽  
Main Chain ◽  
Aqueous Media ◽  
Chain Termination ◽  
The Self ◽  
Absolute Rate ◽  
Nonpolar Solvents ◽  
Hydroperoxy Radical ◽  
Absolute Rate Constant ◽  
Chain Propagation And Termination

The hydroperoxy radical (HOO·) is the main chain propagating and terminating radical in the autoxidation of dilute solutions of 1,4-cyclohexadiene and 1,4-dihydronaphthalene in chlorobenzene at 30 °C. The absolute rate constant for the self-reaction of hydroperoxy radicals (chain termination) in nonpolar solvents is very much higher than previously reported values in aqueous media.

Reactions of 1-substituted 2,4,6-trinitrobenzenes with nucleophiles

1979 ◽  
Vol 44 (5) ◽  
pp. 1453-1459 ◽  
Author(s):  
Jaromír Kaválek ◽  
Ahmad Ashfaq ◽  
Vojeslav Štěrba
Keyword(s):  
Methyl Ether ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Nucleophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Phenyl Ester ◽  
Methyl Derivative ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

Rate constants have been determined of nucleophilic aromatic substitution of 2,4,6-trinitrophenyl methyl ether (Ia), 2,4,6-trinitrophenyl ethanoate (Ic), 2,4,6-trinitrochlorobenzene (Ib), 2,4,6-trinitrodiphenyl ether (Id), 2,4,6-trinitro-4'-bromodiphenyl ether (Ie), 2,3',4,6-tetranitrodiphenyl ether (If) and 2,4,4',6-tetranitrodiphenyl ether (Ig) with methoxide, ethanoate and methyl cyanoethanoate (II) anions in methanol. For the compounds Ia,b rate and equilibrium constants of addition of the anion II(-) at positions 3 and 5 have been measured, too. In reactions of the compounds Ia to Ig with ethanoate anion the first (rate-limiting) step produces the phenyl ester Ic which reacts with a further ethanoate anion to give 2,4,6-trinitrophenol (Ih) and ethanoic anhydride. In reactions of the bromo derivative Ie and, to a still larger extent, compound Id the methyl derivative Ia is formed besides the compound Ih.

Determination of the chain termination rate constants of the radical chain oxidation of organic compounds on antioxidant molecules by the QSPR method

2020 ◽  
Vol 69 (9) ◽  
pp. 1679-1691
Author(s):  
Yu. Z. Martynova ◽  
V. R. Khairullina ◽  
R. N. Nasretdinova ◽  
G. G. Garifullina ◽  
D. S. Mitsukova ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Rate Constants ◽  
Chain Termination ◽  
Radical Chain ◽  
Chain Oxidation ◽  
Termination Rate ◽  
Radical Chain Oxidation ◽  
Oxidation Of Organic Compounds

ABSOLUTE RATE CONSTANTS FOR HYDROCARBON AUTOXIDATION: II. DEUTERO STYRENES AND RING-SUBSTITUTED STYRENES

1965 ◽  
Vol 43 (10) ◽  
pp. 2737-2743 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Rate Constants ◽  
Isotope Effects ◽  
Peroxy Radical ◽  
Propagation Rate ◽  
Chain Termination ◽  
Absolute Rate ◽  
First Order ◽  
Oxidation Rates ◽  
Deuterium Substitution ◽  
Termination Process

The effect of deuterium substitution on the absolute rate constants for the bimolecular chain termination process in the oxidation of styrene indicates that the α-hydrogen is abstracted in this reaction. The first order chain termination process is suppressed both by deuteration of styrene at the α-position and by the addition of heavy water. A possible mechanism for this termination is proposed. There appear to be small secondary deuterium isotope effects in the propagation reaction.The overall oxidation rates and the propagation rate constants are increased by the addition to the aromatic ring of both electron-attracting and electron-releasing substituents. This is attributed in the former case to the increased stability of the resulting styryl radicals and in the latter case to the increased stability of a dipolar transition state. In hydrogen atom abstraction from 2,6-di-t-butyl-4-methylphenol, the peroxy radical from 3-chlorostyrene is more reactive than that from styrene which, in turn, is more reactive than the peroxy radical from 4-methoxy-styrene.

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