On the question of negative activation energies: absolute rate constants by RRKM and G1 theory for methyl + hydrogen halide .fwdarw. methane + halogen (Cl, Br) reactions

1991 ◽  
Vol 95 (24) ◽  
pp. 9900-9908 ◽  
Author(s):  
Yonghua Chen ◽  
Arvi Rauk ◽  
E. Tschuikow-Roux
Keyword(s):  
Rate Constants ◽  
Activation Energies ◽  
Hydrogen Halide ◽  
Absolute Rate

The reactions of O(3P) with 2-propanone, 2-butanone, and 3-pentanone

1986 ◽  
Vol 64 (7) ◽  
pp. 1408-1414 ◽  
Author(s):  
John M. Roscoe
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Substrate Concentration ◽  
Activation Energies ◽  
Absolute Rate ◽  
The Absolute

The reactions of O(3P) with 2-propanone, 2-butanone, and 3-pentanone have been studied kinetically as a function of temperature and substrate concentration. The absolute rate constants for these reactions in the gas phase, in the units M−1 s−1, obey the following relations.[Formula: see text]The activation energies for these reactions are comparable to those for the reactions of O(3P) with alcohols, but the preexponential factors for the reactions of O(3P) with these ketones are significantly smaller than those for the analogous reactions with alcohols. The available data indicate that the reactivity of O(3P) toward ketones shows a variation with polar effects of substituents which is similar to that found for the reactions of OH with ketones.

The reactions of atomic oxygen with 1-propanol and 2-propanol

1979 ◽  
Vol 57 (11) ◽  
pp. 1269-1273 ◽  
Author(s):  
A. L. Ayub ◽  
John M. Roscoe
Keyword(s):  
Rate Constants ◽  
Atomic Oxygen ◽  
Activation Energies ◽  
Steric Effects ◽  
Absolute Rate ◽  
Exponential Factors ◽  
The Absolute

The reactions of O(3P) with n-propanol and isopropanol were studied as a function of temperature. The absolute rate constants for these reactions, in the units M−1 s−1, obey the following relations.[Formula: see text]The activation energies of these reactions are similar to those of the corresponding reactions of methanol and ethanol, although some dependence on the strength of the α-C—H bond is discernible. The nearly constant pre-exponential factors for the reactions of methanol, ethanol, n-propanol, and isopropanol suggest that no special steric effects are present in the reactions of these compounds with O(3P). Mechanisms are discussed for the reactions of n-propanol and isopropanol with O(3P).

The reactions of atomic oxygen with methanol and ethanol

1976 ◽  
Vol 54 (6) ◽  
pp. 984-989 ◽  
Author(s):  
Cynthia M. Owens ◽  
John M. Roscoe
Keyword(s):  
Carboxylic Acid ◽  
Rate Constants ◽  
Atomic Oxygen ◽  
Activation Energies ◽  
Absolute Rate ◽  
Data Support ◽  
The Absolute

The reactions of O(3P) with CH3OH and C2H5OH were studied as a function of temperature. The absolute rate constants for these reactions fit the following expressions:[Formula: see text](Activation energies are in kJ/mol. Rate constants are in 1 mol−1 s−1.) The data support abstraction of the α-H atom as the primary step. The α-C—H bond in ethanol is apparently weaker than that in methanol, and this alters the nature of subsequent steps in the mechanisms for these reactions. The presence of oxygen alters the stoichiometric coefficients for these reactions and produces the corresponding carboxylic acid.

Pulse radiolysis studies XI. Protonation reactions of aromatic anions in some aliphatic alcohols

1967 ◽  
Vol 45 (10) ◽  
pp. 1119-1123 ◽  
Author(s):  
Shigeyoshi Arai ◽  
E. L. Tremba ◽  
J. R. Brandon ◽  
Leon M. Dorfman
Keyword(s):  
Rate Constants ◽  
Pulse Radiolysis ◽  
Activation Energies ◽  
Aliphatic Alcohols ◽  
Absolute Rate ◽  
Protonation Reaction ◽  
Exponential Factors ◽  
Aromatic Anions ◽  
Anion Radicals

The protonation reaction of aromatic anion radicals in the aliphatic alcohols, [Formula: see text]has been investigated by the pulse radiolysis method. Activation energies for this reaction have been determined for the anthracenide anion and diphenylide anion in methanol, ethanol, and isopropanol, and for the naphthalenide anion in isopropanol. Absolute rate constants have been determined as well for the phenanthrenide, o-terphenylide, and m-terphenylide anions in isopropanol at 25 °C. The values for the rate constants, activation energies, and the pre-exponential factors are given. Those properties of the system which determine the kinetics are briefly discussed.

Kinetics of esterification of monoisopropylphenols with phosphoryl trichloride

1989 ◽  
Vol 54 (5) ◽  
pp. 1311-1317
Author(s):  
Miroslav Magura ◽  
Ján Vojtko ◽  
Ján Ilavský
Keyword(s):  
Liquid Phase ◽  
Rate Constants ◽  
Reaction Rates ◽  
Activation Energies ◽  
The Individual ◽  
Kinetics Of

The kinetics of liquid-phase isothermal esterification of POCl3 with 2-isopropylphenol and 4-isopropylphenol have been studied within the temperature intervals of 110 to 130 and 90 to 110 °C, respectively. The rate constants and activation energies of the individual steps of this three-step reaction have been calculated from the values measured. The reaction rates of the two isomers markedly differ: at 110 °C 4-isopropylphenol reacts faster by the factors of about 7 and 20 for k1 and k3, respectively. This finding can be utilized in preparation of mixed triaryl phosphates, since the alkylation mixture after reaction of phenol with propene contains an excess of 2-isopropylphenol over 4-isopropylphenol.

ChemInform Abstract: ABSOLUTE RATE CONSTANTS FOR REACTIONS OF PHENYL RADICALS

1978 ◽  
Vol 9 (20) ◽  
Author(s):  
V. MADHAVAN ◽  
R. H. SCHULER ◽  
R. W. FESSENDEN
Keyword(s):  
Rate Constants ◽  
Absolute Rate ◽  
Phenyl Radicals

Reactions of the hydroxyl radical. Part 2.—Determination of absolute rate constants

1965 ◽  
Vol 61 (0) ◽  
pp. 1417-1424 ◽  
Author(s):  
G. E. Adams ◽  
J. W. Boag ◽  
B. D. Michael
Keyword(s):  
Hydroxyl Radical ◽  
Rate Constants ◽  
Absolute Rate
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