Steric Factor and Activation Energy of the Reaction Na+C2H5Cl = NaCl+C2H5

1952 ◽  
Vol 20 (6) ◽  
pp. 1016-1020 ◽  
Author(s):  
R. J. Cvetanović ◽  
D. J. Le Roy
Keyword(s):  
Activation Energy ◽  
Steric Factor

Aromatic oxidation by cobaltic acetate in acetic acid

1969 ◽  
Vol 47 (3) ◽  
pp. 387-392 ◽  
Author(s):  
Koichiro Sakota ◽  
Yoshio Kamiya ◽  
Nobuto Ohta
Keyword(s):  
Activation Energy ◽  
Electron Transfer ◽  
Acetic Acid ◽  
Bond Energy ◽  
Hydrogen Abstraction ◽  
Steric Factor ◽  
Benzyl Acetate ◽  
Kcal Mole ◽  
First Order ◽  
Reversible Electron Transfer

A detailed kinetic study of oxidation of toluene and its derivatives by cobaltic acetate in 95 vol% acetic acid is reported. The reaction was found to be profoundly affected by a steric factor and rather insensitive to the C—H bond energy. The order of reactivities of various alkylbenzenes is quite reversal to that of hydrogen abstraction reactions. The reaction was of first-order with respect to toluene, of second-order with respect to cobaltic ion and of inverse first-order with respect to cobaltous ion. The oxidation by cobaltic ion seems to proceed via an initial reversible electron transfer from toluene to cobaltic ion, yielding [Formula: see text] which is oxidized into benzyl acetate by another cobaltic ion. The apparent activation energy for toluene was found to be 25.3 kcal mole−1, and the same activation energy was found for ethylbenzene, cumene, diphenylmethane, and triphenylmethane.

ADDITION OF ETHYL RADICALS TO ETHYLENE

1957 ◽  
Vol 35 (7) ◽  
pp. 588-594 ◽  
Author(s):  
J. A. Pinder ◽  
D. J. Le Roy
Keyword(s):  
Activation Energy ◽  
Reaction Zone ◽  
Addition Reaction ◽  
Steric Factor ◽  
Square Root ◽  
Temperature Range ◽  
Ethyl Radical ◽  
Ethyl Radicals

The addition of ethyl radicals to ethylene has been studied in the temperature range 58° to 123 °C. The radicals were produced by the mercury photosensitized decomposition of hydrogen in the presence of ethylene, and the rate of the addition reaction was measured in terms of the rate of formation of n-hexane by the combination of ethyl and butyl radicals. Corrections were made for the non-uniformity of radical concentrations in the reaction zone. Assuming a negligible activation energy for the combination of two ethyl radicals, the activation energy for the addition reaction is 5.5 kcal. per mole; the steric factor, relative to the square root of the steric factor for ethyl radical combination, is 5.0 × 10−5.

THE STERIC FACTOR IN THE HYDROLYSIS OF β-1,4′-OLIGOGLUCOSIDES BY MYROTHECIUM CELLULASE

1956 ◽  
Vol 34 (1) ◽  
pp. 102-115 ◽  
Author(s):  
D. R. Whitaker
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Rate Constants ◽  
Activation Energies ◽  
Enzymic Activity ◽  
Degree Of Polymerization ◽  
Steric Factor ◽  
Collision Theory ◽  
Hydrolysis Of

A comparison of the rate constants and activation energies for the hydrolysis of cellobiose, cellotriose, cellotetraose, and cellopentaose by Myrothecium cellulase showed that while the rate constant was increased by a factor of about 450 as the degree of polymerization (D.P.) of the substrate was increased from two to five, the activation energy remained at about 12,000 cal. The results are interpreted, in terms of classical collision theory, as indicating that the increase in rate constant with D.P. is determined by an increase in the steric factor with D.P. Addition of a β-linked sorbityl group to an oligoglucoside increased the rate constant; the increase was less than that from addition of an anhydroglucose unit and, relative to the latter, diminished as the D.P. of the chain undergoing addition was increased. Exposing the enzyme to conditions favoring thermal or surface denaturation caused varying losses in enzymic activity towards the four oligoglucosides; wherever the loss in activity towards one oligoglucoside differed substantially from the loss in activity towards any other oligoglucoside, the greater loss was shown towards the substrate of lower D.P. The results are discussed.

THE PHOTO-OXIDATION OF AZOMETHANE

1955 ◽  
Vol 33 (3) ◽  
pp. 496-506 ◽  
Author(s):  
G. R. Hoey ◽  
K. O. Kutschke
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Room Temperature ◽  
Major Product ◽  
Steric Factor ◽  
Primary Process ◽  
Methyl Radicals ◽  
Low Oxygen ◽  
Secondary Product ◽  
Photo Oxidation

The photo-oxidation of azomethane has been studied at low oxygen pressures (0.02 to 1 mm.) in the temperature range ca. 25 °C. to 161 °C. The primary process in the normal photolysis of azomethane is essentially unaffected by the presence of oxygen. Carbon monoxide is probably a secondary product of the oxidation of methyl radicals. Carbon dioxide formation is quite small, and therefore neither methyl radicals nor CH3N=N—CH2 radicals are oxidized appreciably to carbon dioxide. Nitrous oxide, which is a major product of the oxidation, is most likely formed from the oxidation of CH3N=NCH2 radicals. The suggested mechanism of N2O formation is:[Formula: see text] The reaction of methyl radicals with oxygen was found to proceed with a negligible activation energy and a steric factor of the order of 10−2. Evidence for the occurrence of the reactions[Formula: see text]at room temperature was obtained.

APPLICATION OF DIFFUSION FLAME TECHNIQUE TO THE REACTION BETWEEN NITROGEN ATOMS AND ETHYLENE

1949 ◽  
Vol 27b (8) ◽  
pp. 732-737
Author(s):  
C. A. Winkler ◽  
J. H. Greenblatt
Keyword(s):  
Activation Energy ◽  
Temperature Coefficient ◽  
Diffusion Flame ◽  
Rate Constants ◽  
Steric Factor ◽  
Temperature Range

Rate constants for the reaction between nitrogen atoms and ethylene have been obtained by diffusion flame technique over the temperature range 273° to 373 °C. An activation energy of about 3 kcal. has been obtained from the temperature coefficient of these rate constants, and using this value a steric factor of 10−2 has been calculated.

THE REACTION OF NITROGEN ATOMS WITH ETHYLENE

1949 ◽  
Vol 27b (8) ◽  
pp. 721-731
Author(s):  
C. A. Winkler ◽  
J. H. Greenblatt
Keyword(s):  
Activation Energy ◽  
Double Bond ◽  
Hydrogen Cyanide ◽  
Steric Factor ◽  
Methyl Radical

Reaction of nitrogen atoms with ethylene has been found to produce hydrogen cyanide, ethane, and a polymerizable material. The yield of hydrogen cyanide was approximately 70% of the ethylene consumed by nitrogen atoms, while the amount of polymerizable material averaged about 16% by weight of the hydrogen cyanide produced. The yield of ethane increased as the excess of ethylene over nitrogen atoms was increased. The reaction was found to proceed by "clean-up of nitrogen atoms. An activation energy of 6.9 kcal. was calculated from collision yields, a steric factor of 0.1 being assumed. A mechanism for the reaction has been proposed, involving rupture of the ethylene double bond with formation of hydrogen cyanide and a methyl radical, the methyl radical then reacting further with nitrogen atoms.

THE GAS PHASE REACTION OF METHYL RADICALS WITH HEXAFLUOROACETONE

1957 ◽  
Vol 35 (10) ◽  
pp. 1216-1224 ◽  
Author(s):  
G. O. Pritchard ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Steric Factor ◽  
Phase Reaction ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Gas Phase Reaction

The photolytic and thermal decomposition of azomethane in the presence of hexafluoroacetone produces small amounts of fluorinated products, mainly fluoroform. The mechanism of this and related reactions is discussed. It is concluded that the proposed reaction.[Formula: see text]has an activation energy of about 6 kcal./mole, with a steric factor of about 10−5.

The decomposition of n -hexane II. By reaction with atomic hydrogen

1958 ◽  
Vol 243 (1235) ◽  
pp. 449-457
Keyword(s):  
Activation Energy ◽  
Atomic Hydrogen ◽  
Flow System ◽  
Product Distribution ◽  
Steric Factor ◽  
Hydrogen Atoms ◽  
Initial Product ◽  
Molecular Weights ◽  
Main Component ◽  
Product Fraction

The reaction of hexane with hydrogen atoms produced by mercury photosensitization, has been studied in a flow system at 300° C. About one-third of the products had molecular weights greater than that of hexane, and dodecane was the main component of this product fraction. Hydrogen: hexane ratios up to 55:1 were employed and in these conditions virtually all the quenching of excited mercury atoms was brought about by hydrogen. The activation energy and steric factor of the reaction C 6 H 14 + H = C 6 H 13 + H 2 are estimated at 6 kcal and 10 -4 , respectively. These values are in accord with those recently obtained for the corresponding reactions involving other n -paraffins. The initial product distribution was similar to that obtained in the mercury photosensitized decomposition of hexane and the findings suggest that products of lower molecular weight than hexane derive almost completely from thermal decomposition of hexyl radicals. ‘Atomic cracking’ appears to be of little importance at these high temperatures.

THE KINETICS OF THE REACTION OF ATOMIC HYDROGEN WITH METHANE

1964 ◽  
Vol 42 (7) ◽  
pp. 1638-1644 ◽  
Author(s):  
J. W. S. Jamieson ◽  
G. R. Brown
Keyword(s):  
Activation Energy ◽  
Electric Discharge ◽  
Atomic Hydrogen ◽  
Flow System ◽  
Steric Factor ◽  
Primary Reaction ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Fast Flow ◽  
Kinetics Of

Reinvestigation of the reaction of hydrogen atoms, produced by electric discharge, with methane in a fast flow system has given an activation energy of 7.4 ± 1.1 kcal/mole and a steric factor of about 10−3 for the primary reaction, H + CH4 → H2 + CH3.

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