THE REACTIONS OF METHYL RADICALS WITH CYCLOPROPANE, ETHYLENE OXIDE, METHANOL, AND DIMETHYL ETHER

1950 ◽  
Vol 28b (7) ◽  
pp. 395-402 ◽  
Author(s):  
M. K. Phibbs ◽  
B. deB. Darwent
Keyword(s):  
Ethylene Oxide ◽  
Dimethyl Ether ◽  
Activation Energies ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Photochemical Decomposition

The reactions of methyl radicals, produced by the photochemical decomposition of dimethylmercury, with cyclopropane, ethylene oxide, methanol and dimethyl ether have been investigated between 100° and 250 °C. The following activation energies (kcal. mole−1) for the abstraction of hydrogen from the compounds by methyl radicals were found: cyclopropane, 10.2; ethylene oxide 9.6; methanol, 8.2; and dimethyl ether, 8.0. The probability factors have been shown to be about 10−4 for all the compounds investigated.

THE REACTIONS OF TRIFLUOROMETHYL RADICALS WITH PROPANE, n-BUTANE, AND ISOBUTANE

1956 ◽  
Vol 34 (2) ◽  
pp. 103-107 ◽  
Author(s):  
P. B. Ayscough ◽  
E. W. R. Steacie
Keyword(s):  
Rate Constants ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Methyl Radicals ◽  
Kcal Mole

A study of the reactions of trifluoromethyl radicals, produced by the photolysis of hexafluoroacetone, with propane, n-butane, and isobutane has been made. The rate constants of the hydrogen-abstraction reactions have been determined at temperatures between 27 °C and 119 °C and the activation energies found to be 6.5 ± 0.5, 5.1 ± 0.3, and 4.7 ± 0.3 kcal./mole respectively. These values are compared with those obtained for the reactions with methane and ethane, and with the corresponding reactions of methyl radicals.

THE VAPOR PHASE PHOTOLYSIS OF HEXAFLUOROACETONE IN THE PRESENCE OF METHANE AND ETHANE

1955 ◽  
Vol 33 (5) ◽  
pp. 743-749 ◽  
Author(s):  
P. B. Ayscough ◽  
J. C. Polanyi ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Vapor Phase ◽  
Activation Energies ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Photolytic Decomposition

The photolytic decomposition of hexafluoroacetone by light of wavelength 3130 Å has been used to produce trifluoromethyl radicals for a study of their reactions with methane and ethane. It has been shown that these radicals abstract hydrogen with greater facility than do methyl radicals. The activation energies for the two reactions[Formula: see text]and[Formula: see text]are found to be 10.3 ± 0.5 kcal./mole and 7.5 ±0.5 kcal./mole respectively, if one can assume zero activation energy for the recombination of trifluoromethyl radicals.

THE REACTION OF METHYL RADICALS WITH CH3CHO AND CH3CDO

1955 ◽  
Vol 33 (1) ◽  
pp. 31-38 ◽  
Author(s):  
P. Ausloos ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energies ◽  
Disproportionation Reaction ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Direct Photolysis

Azomethane has been photolyzed in the presence of CH3CHO and CH3CDO, and the results compared with the direct photolysis of the aldehydes. The activation energies found were 6.8 and 7.8 kcal./mole, respectively, for the reactions[Formula: see text]The results furnish evidence that only an acyl hydrogen is captured. Evidence has also been found for the occurrence of wall reactions and the disproportionation reaction[Formula: see text]

Reactions of trifluoromethyl and methyl radicals with ethylene oxide

1970 ◽  
Vol 48 (22) ◽  
pp. 3601-3604 ◽  
Author(s):  
S. H. Jones ◽  
E. Whittle
Keyword(s):  
Activation Energy ◽  
Ethylene Oxide ◽  
Published Data ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Arrhenius Parameters

The reaction between CF3 radicals and ethylene oxide was studied in the range 60–228 °C using CF3I as a radical source. For the reactions,[Formula: see text]we obtain[Formula: see text]where θ = 2.3 RT kcal mole−1Published data of Phibbs and Darwent on the reaction[Formula: see text]have been re-calculated and it is suggested that both the original and re-calculated values of the activation energy E5 are too low. The Arrhenius parameters for the reactions of CF3 and CH3 radicals with ethylene oxide are compared with those for related reactions.

THE REACTION OF METHYL RADICALS WITH ISOBUTANE

1953 ◽  
Vol 31 (5) ◽  
pp. 505-510 ◽  
Author(s):  
M. H. Jones ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Energy Of Activation ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
A Value ◽  
Photochemical Decomposition

An investigation is reported of the reaction of methyl radicals, produced in the photochemical decomposition of azomethane, with isobutane. The energy of activation of this process was found to be 6.7 ± 0.8 kcal./mole, assuming that the combination of methyl radicals has an activation energy of zero. From some experiments with n-butane, a value of 9 ± 1 kcal./mole was obtained.

THE REACTION OF METHYL RADICALS WITH FORMALDEHYDE

1959 ◽  
Vol 37 (9) ◽  
pp. 1462-1468 ◽  
Author(s):  
A. R. Blake ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Addition Reactions ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
A Value ◽  
Abstraction Reaction ◽  
Butyl Peroxide

The pyrolysis of di-t-butyl peroxide has been reinvestigated and used as a source of methyl radicals to study the abstraction reaction between methyl radicals and formaldehyde. At low [HCHO]/[peroxide] ratios the system was simple enough for kinetic analysis, and a value of 6.6 kcal/mole was obtained for the activation energy. At higher [HCHO]/[peroxide] ratios the system became very complicated, possibly due to the increased importance of addition reactions.

Coordination of silicon tetrafluoride with alicyclic ethers and dimethyl ether

1968 ◽  
Vol 46 (6) ◽  
pp. 987-993 ◽  
Author(s):  
J. P. Guertin ◽  
M. Onyszchuk
Keyword(s):  
Ethylene Oxide ◽  
Dimethyl Ether ◽  
Condensed Phase ◽  
Silicon Tetrafluoride ◽  
Relative Order ◽  
Trimethylene Oxide

Tensimetric titrations at −78° of silicon tetrafluoride with ethylene oxide, trimethylene oxide, tetrahydrofuran, tetrahydropyran, and dimethyl ether prove the formation of only 1:2 complexes, SiF4•2-(ether). All are unstable at 25° and either dissociate completely, as do SiF4•2(CH2)4O, SiF4•2(CH2)5O, and SiF4•2(CH3)2O, or decompose into SiF4 and a polymethylene oxide polymer, as do SiF4•2(CH2)2O and SiF4•2(CH2)3O. Silicon tetrafluoride does not coordinate with 1,4-dioxane in the range −94 to 25° and less than 1 atm pressure. Condensed phase heats of dissociation of SiF4•2(ether) complexes follow the order (CH2)3O > (CH2)4O > (CH2)5O ≥ (CH2)2O > (CH3)2O, which suggests that this is the relative order of basicities towards SiF4.

THE CHEMISTRY OF ETHYLENE OXIDE: V. THE REACTION OF ETHYLENE OXIDE WITH HALIDE IONS IN NEUTRAL AND ACID SOLUTION

1952 ◽  
Vol 30 (3) ◽  
pp. 169-176 ◽  
Author(s):  
A. M. Eastham ◽  
G. A. Latremouille
Keyword(s):  
Aqueous Solution ◽  
Ethylene Oxide ◽  
Acid Solution ◽  
Activation Energies ◽  
Hydrogen Halide ◽  
Halide Ions ◽  
Neutral Aqueous Solution ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The rates of reaction of halide ions with ethylene oxide in neutral aqueous solution and the rate of hydrolysis of ethylene oxide in acid solution have been measured and the activation energies determined. From these data and from the ratio of glycol to chlorohydrin formed when ethylene oxide reacts with excess aqueous hydrogen halide, the rates of the acid-catalyzed addition of halide ions to ethylene oxide at 25 °C. have been estimated.

The photochemical and thermal decompositions of hydrogen sulphide

1953 ◽  
Vol 216 (1126) ◽  
pp. 344-361 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Quantum Yield ◽  
Hydrogen Sulphide ◽  
Low Temperatures ◽  
Room Temperature ◽  
Large Fraction ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Photochemical Decomposition ◽  
Bimolecular Mechanism

The photochemical decomposition of hydrogen sulphide has been investigated at pressures between 8 and 550 mm of mercury and at temperatures between 27 and 650° C, using the narrow cadmium line ( λ 2288) and the broad mercury band (about λ 2550). At room temperature the quantum yield increases with pressure from 1.09 at 30 mm to 1.26 at 200 mm. Above 200 mm pressure there was no further increase in the quantum yield. Temperature had little effect on the quantum yield at λ 2550, but there was a marked increase in the rate of hydrogen production between 500 and 650° C with 2288 Å radiation. This may have been caused by the decomposition of excited hydrosulphide radicals. The results are consistent with a mechanism involving hydrogen atoms and hydrosulphide radicals. The mercury-photosensitized reaction is less efficient than the photochemical decomposition, the quantum yield being only about 0.45. The efficiency increased with temperature and approached unity at high temperatures and pressures. This agrees with the suggestion that a large fraction of the quenching collisions lead to the formation of Hg ( 3 P 0 ) atoms. The thermal decomposition is heterogeneous at low temperatures and becomes homogeneous and of the second order at 650° C. The experimental evidence suggests the bimolecular mechanism 2H 2 S → 2H 2 + S 2 . The activation energies are 25 kcal/mole (heterogeneous) and 50 kcal/mole (homogeneous).

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