Absolute Rate Constants for Hydrocarbon Autoxidation. XXII. The Autoxidation of some Vinyl Compounds

1972 ◽  
Vol 50 (14) ◽  
pp. 2298-2304 ◽  
Author(s):  
J. A. Howard
Keyword(s):  
Rate Constants ◽  
Addition Reaction ◽  
Peroxy Radical ◽  
Stabilization Energy ◽  
Peroxy Radicals ◽  
Absolute Rate ◽  
Termination Rate ◽  
Vinyl Compound ◽  
Rate Constants For Addition

Absolute propagation and termination rate constants have been determined for the autoxidation of some vinyl compounds at 30°. Rates of propagation depend on the structure of both the peroxy radical and the vinyl compound. The reactivity of peroxy radicals towards addition increases as the electron-withdrawing capacity of the α-substituent increases. Rate constants for addition of t-butylperoxy radicals to vinyl compounds, [Formula: see text] fit the equation[Formula: see text]where Es is the estimated stabilization energy of the β-peroxyalkyl radical (in kcal/mol) formed in the addition reaction.

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. XVII. The oxidation of some cyclic ethers

1969 ◽  
Vol 47 (20) ◽  
pp. 3809-3815 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Hydrogen Atom ◽  
Rate Constants ◽  
Transfer Rate ◽  
Chain Transfer ◽  
Hydrogen Atom Abstraction ◽  
Cyclic Ethers ◽  
Peroxy Radicals ◽  
Absolute Rate ◽  
Termination Rate

The propagation and termination rate constants have been determined for the autoxidation of 1,4-dioxan, tetrahydropyran, tetrahydrofuran, 2,5-dimethyltetrahydrofuran, and phthalan. The rate constants for α-hydrogen atom abstraction from some of the ethers by the tetralylperoxy radical and from tetralin by some ether peroxy radicals have been measured and compared. The chain transfer rate constants have been estimated for the reaction of the cumylperoxy radical with α-hydroperoxytetrahydrofuran, α-hydroperoxytetrahydropyran, and α-ethoxyethyl hydroperoxide.

Absolute rate constants for hydrocarbon autoxidation. XIX. Oxidation of some α-substituted toluenes

1970 ◽  
Vol 48 (14) ◽  
pp. 2165-2172 ◽  
Author(s):  
J. A. Howard ◽  
S. Korcek
Keyword(s):  
Liquid Phase ◽  
Rate Constants ◽  
Bromine Atom ◽  
Peroxy Radical ◽  
Phenyl Radical ◽  
Absolute Rate ◽  
Termination Rate ◽  
Substituted Toluenes

Absolute propagation and termination rate constants have been measured for the liquid phase autoxidation of some α-substituted toluenes at 30 °C. Rate constants for reaction of α-substituted toluenes with their own peroxy radical and with the t-butylperoxy radical have been compared. It would appear that the reactivity of an α-substituted benzylperoxy radical depends on the nature of the α-substituent.Reactivities of α-substituted toluenes towards the t-butylperoxy radical, the bromine atom, and the phenyl radical have been compared.

Absolute rate constants for hydrocarbon oxidation. XII. Rate constants for secondary peroxy radicals

1968 ◽  
Vol 46 (16) ◽  
pp. 2661-2666 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Rate Constants ◽  
Hydrogen Abstraction ◽  
Peroxy Radical ◽  
Hydrocarbon Oxidation ◽  
Peroxy Radicals ◽  
Absolute Rate ◽  
Lower Reactivity ◽  
Inductive Effects ◽  
Steric Factors

Rate constants have been measured for hydrogen abstraction from four aralkanes and addition to two aralkenes by five secondary and one primary peroxy radical. These rate constants appear to show a slight dependence on the structure of the attacking peroxy radicals which may be due to the inductive effects of the substituents on the radical. The secondary and primary peroxy radicals are generally about 2–4 times more reactive than tertiary peroxy radicals in abstraction and 4–8 times more reactive in addition. The lower reactivity of tertiary peroxy radicals is probably due to steric factors.

Absolute rate constants for hydrocarbon autoxidation. XIV. Termination rate constants for tertiary peroxy radicals

1969 ◽  
Vol 47 (20) ◽  
pp. 3793-3795 ◽  
Author(s):  
J. A. Howard ◽  
K. Adamic ◽  
K. U. Ingold
Keyword(s):  
Electron Spin Resonance ◽  
Rate Constants ◽  
Chain Termination ◽  
Peroxy Radicals ◽  
Absolute Rate ◽  
Termination Rate ◽  
Spin Resonance ◽  
After Effect ◽  
Effect Method ◽  
Good Agreement

Absolute rate constants for chain termination by ten t-peroxy radicals have been measured at 30° by the rotating sector technique, the photochemical pre- and after-effect method, and by electron spin resonance. The different methods generally give results in good agreement with one another. The termination rate constants vary from a low of ∼4 × 102 M−1 s−1 for t-butylperoxy to a high of ∼3 × 104 M−1 s−1 for 1,1-diphenylethylperoxy radicals.

The kinetics of the oxidation of mixtures of benzaldehyde and n -decanal

1953 ◽  
Vol 218 (1133) ◽  
pp. 163-175 ◽  
Keyword(s):  
Co Oxidation ◽  
Rate Constants ◽  
Peroxy Radical ◽  
Peroxy Radicals ◽  
Absolute Rate ◽  
Kinetic Chain ◽  
Reaction Coefficient ◽  
The Individual ◽  
Kinetics Of ◽  
Oxidation System

The photo-induced co-oxidation of liquid benzaldehyde and decanal mixtures has been investigated as representative of a co-oxidation system of two components. The kinetics of the reaction clearly show that these aldehydes do not separately oxidize; instead, both molecules are involved in a single kinetic chain. The system is analogous to that encountered in copolymerization. By analysis of the aldehyde ratio during oxidation the relative reactivity of the two aldehydes to a given peroxy radical may be determined. Utilizing the rate constants for the oxidation of the individual aldehydes, the absolute rate constants for the four propagation steps in the co-oxidation system can be calculated. By making use of the retarder technique the rate of initiation of oxidation has been determined as a function of aldehyde composition. The measurement of the overall rate of oxidation makes it possible to determine the cross-reaction coefficient for the interaction of the peroxy radicals. A so-called Φ value for this coefficient is 4.

Absolute rate constants for hydrocarbon autoxidation. 25. Rate constants for hydrogen atom abstraction from alkanes by the tert-butylperoxy radical

1978 ◽  
Vol 56 (24) ◽  
pp. 3047-3053 ◽  
Author(s):  
J. H. B. Chenier ◽  
S. B. Tong ◽  
J. A. Howard
Keyword(s):  
Hydrogen Atom ◽  
Rate Constants ◽  
Kinetic Isotope Effect ◽  
Peroxy Radical ◽  
Hydrogen Atom Abstraction ◽  
Labile Hydrogen ◽  
Absolute Rate ◽  
Steric Strain ◽  
Kinetic Isotope ◽  
Tert Butyl Hydroperoxide

Rate constants for abstraction of secondary and tertiary hydrogens from structurally different alkanes by the tert-butylperoxy radical in solution at 30 °C have been determined by competitive experiments in the presence of tert-butyl hydroperoxide. Rate constants fall in the range 1 × 10−4to 9 × 10−4and 1 × 10−3–2 × 10−2 M−1 s−1 for secondary and tertiary aliphatic C—H bonds, respectively. The most reactive secondary hydrogen is, therefore, almost as reactive as the least reactive tertiary hydrogen. Differences in reactivity within a type of aliphatic C—H bond are governed by differences in steric hindrance to attack by the peroxy radical and by relief of steric strain upon removal of the labile hydrogen. Rate constants for reaction of perdeuterated methylcyclohexane and 3-methylpentane are much smaller than the values calculated from the maximum primary kinetic isotope effect for this reaction.

Solvent, Substituent, and Temperature Effects on the Absolute Rate Constants for Addition of Methoxytrimethylsilane to 1,1-Diarylsilenes

2001 ◽  
Vol 20 (5) ◽  
pp. 932-936 ◽  
Author(s):  
William J. Leigh ◽  
Christine J. Bradaric ◽  
Tracy L. Morkin ◽  
Xiaojing Li
Keyword(s):  
Rate Constants ◽  
Temperature Effects ◽  
Absolute Rate ◽  
The Absolute ◽  
Rate Constants For Addition

Absolute rate constants for hydrocarbon autoxidation. XVIII. Oxidation of some acyclic ethers

1970 ◽  
Vol 48 (6) ◽  
pp. 873-880 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Rate Constants ◽  
Propagation Rate ◽  
Phenyl Ether ◽  
Isopropyl Ether ◽  
Benzyl Ether ◽  
Absolute Rate ◽  
Butyl Ether ◽  
Termination Rate ◽  
Benzyl Phenyl Ether

Propagation and termination rate constants have been measured for autoxidation of benzyl phenyl ether, benzyl-t-butyl ether, isopropyl ether, and benzyl ether. In the case of isopropyl ether and benzyl ether, estimates have been made of inter- and intramolecular propagation rate constants. Reactivities of acyclic ethers towards the t-butylperoxy radical have been determined. Rate constants for autoxidation of cyclic and acylic ethers have been summarized and compared.

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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