HYDROGEN ATOM ABSTRACTION BY ETHYL-d5 RADICALS. PART I

1960 ◽  
Vol 38 (9) ◽  
pp. 1576-1589 ◽  
Author(s):  
P. J. Boddy ◽  
E. W. R. Steacie
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Abstraction ◽  
Deuterium Atom ◽  
Structural Features ◽  
Activation Energies ◽  
Hydrogen Atom Abstraction ◽  
Kcal Mole ◽  
Temperature Range ◽  
Exponential Factors ◽  
Ethyl Radicals

The photolysis of 3-pentanone-d10 has been used as a source of deuterated ethyl radicals and some of their hydrogen abstraction reactions studied over the temperature range 50–300 °C.The compounds neopentane, n-butane, and isobutane were chosen as representative of the basic structural features in the alkane series. The activation energies for abstraction [Formula: see text] are respectively 12.60 ± 0.7, 10.4 ± 0.75, and 8.9 ± 0.6 kcal/mole and the pre-exponential factors (log10(A8/A4)) are 0.300 ± 0.09, 0.082 ± 0.09, and −0.334 ± 0.066 where[Formula: see text]For abstraction of a deuterium atom from the ketone the values obtained are [Formula: see text] in agreement with previous investigations (1, 2).The value of the disproportionation to combination ratio for C2D5 radicals is 0.0985 ± 0.008 independent of temperature.

Reactions of trifluoromethyl radicals. II. Hydrogen abstraction from monochlorosilane

1973 ◽  
Vol 26 (6) ◽  
pp. 1269 ◽  
Author(s):  
NL Arthur ◽  
BR Harman
Keyword(s):  
Hydrogen Atom ◽  
Rate Constant ◽  
Experimental Error ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Hydrogen Atom Abstraction ◽  
Temperature Range ◽  
Average Value

Hydrogen atom abstraction from SiH3Cl by CF3 radicals ����������������� CF3 + SiH3Cl → CF3H+SiH2Cl������������������� (1) has been studied in the temperature range 69-168�. The rate constant, based on Ayscough's value of 1013.36 cm3 mol-1 s-1 for the recombination of CF3 radicals, is given by (k1 in cm3 mol-1 s-1, E in kJ mol-1): ������������������ logk1 = (12.38�0.06)-(25.72�0.41)/2.303RT At 400 K, the rate constant for CF3 + SiH3Cl is greater than the average value reported for CF3+SiHCl3 by a factor of 3.6. This is due to a difference in A factors since the activation energies are equal within experimental error.

Reactions of trifluoromethyl radicals. I. Hydrogen abstraction from dimethyl sulphide

1972 ◽  
Vol 25 (4) ◽  
pp. 803 ◽  
Author(s):  
NL Arthur ◽  
KS Yeo
Keyword(s):  
Hydrogen Atom ◽  
Rate Constant ◽  
Hydrogen Abstraction ◽  
Reverse Reaction ◽  
Thermochemical Data ◽  
Hydrogen Atom Abstraction ◽  
Dimethyl Sulphide ◽  
Temperature Range

Hydrogen atom abstraction from (CH3)2S by CF3 radicals has been studied in the temperature range 79-167�: (1) CF3 + CH3SCH3 ←→ CF3H + CH3SCH2 (-1) The rate constant, based on Ayscough's value of 1013.36cmS mol-l s-l for the recombination of CF3 radicals, is given by (k1 in cm3 mol-1 s-l, E in J mol-l): Logk1 = (12.05 � 0.02)-(28710 � 130)/2.303RT Combination of these results with thermochemical data gives a calculated value of log k-1 = 12.2 - 62600/2.303RT for the rate constant of the reverse reaction. ΔH�f(CH3SCH2) and S�(CH3SCH2) are estimated to be 155.6 kJ mol-l and 290 J K-l mol-1 respectively.

THE REACTIONS OF METHYL AND ETHYL RADICALS WITH DIETHYL KETONE

1954 ◽  
Vol 32 (6) ◽  
pp. 593-597 ◽  
Author(s):  
P. Ausloos ◽  
E. W. R. Steacie
Keyword(s):  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Diethyl Ketone ◽  
Temperature Range ◽  
Steric Factors ◽  
Ethyl Radicals

The hydrogen-abstraction reactions of methyl and ethyl radicals from diethyl ketone have been studied in the temperature range 25 to 160 °C. Azomethane and azoethane were used as photochemical sources of methyl and ethyl radicals. The activation energies found were 7.0 and 7.6 kcal., respectively, for the reactions:[Formula: see text][Formula: see text]If the combination of both methyl and ethyl radicals is assumed to occur at every collision, the steric factors for the two reactions are E1 = 7.4 × 10−4, E2 = 7.1 × 10−4.

Reactions of trifluoromethyl radicals. V. Hydrogen abstraction from methyl acetate and methyl (2H3)Acetate

1980 ◽  
Vol 33 (7) ◽  
pp. 1437
Author(s):  
NL Arthur ◽  
PJ Newitt
Keyword(s):  
Isotope Effect ◽  
Rate Constants ◽  
Methoxy Group ◽  
Methyl Acetate ◽  
Kinetic Isotope Effect ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Temperature Range ◽  
Kinetic Isotope ◽  
Acetyl Group

Hydrogen abstraction by CF3 radicals from CH3COOCH3 and CD3COOCH3 has been studied in the temperature range 78-242°, and data have been obtained for the reactions: CF3 + CH3COOCH3 → CF3H+[C3H5O2] �������������(3) CF3 + CH3COOCH3 → CF3H+CH2COOCH3������������ (4) CF3 + CD3COOCH3 → CF3D+CD2COOCH3������������ (6) CF3 + CD3COOCH3 → CF3H+CD3COOCH2������������ (7) The corresponding rate constants, based on the value of 1013.36 cm3 mol-1 S-1 for the recombination of CF3 radicals, are given by (k in cm3 mol-1 s-1 and E in J mol-1): logk3 = (11.52�0.05)-(35430�380)/19.145T ���� (3)logk4 = (11.19�0.07)-(34680�550)/19.145T ���� (4)logk6 = (11.34�0.06)-(46490�490)/19.145T ���� (6)logk7 = (11.26�0.05)-(36440�400)/19.145T ���� (7)At 400 K, 59% of abstraction occurs from the acetyl group, and 41 % from the methoxy group. The kinetic isotope effect at 400 K for attack on the acetyl group is 25, due mainly to a difference in activation energies.

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.

Theoretical Pre-exponential Factors for Hydrogen Atom Abstraction Reactions1

1957 ◽  
Vol 79 (1) ◽  
pp. 29-32 ◽  
Author(s):  
David J. Wilson ◽  
Harold S. Johnston
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Atom Abstraction ◽  
Exponential Factors

Influence of the double bond on the hydrogen abstraction reactions of methyl esters with hydrogen radical: an ab initio and chemical kinetic study

RSC Advances ◽  
2015 ◽  
Vol 5 (84) ◽  
pp. 68314-68325 ◽  
Author(s):  
Quan-De Wang ◽  
Weidong Zhang
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Ab Initio ◽  
Kinetic Study ◽  
Rate Constants ◽  
Methyl Esters ◽  
Hydrogen Abstraction ◽  
Chemical Kinetic ◽  
Hydrogen Atom Abstraction ◽  
Hydrogen Radical

This work reports a systematic ab initio and chemical kinetic study of the rate constants for hydrogen atom abstraction reactions by hydrogen radical on the isomers of unsaturated C6 methyl esters.

THE REACTIONS OF PERFLUOROETHYL RADICALS WITH HYDROGEN AND METHANE

1960 ◽  
Vol 38 (11) ◽  
pp. 2128-2135 ◽  
Author(s):  
S. J. W. Price ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Hydrogen Abstraction ◽  
Frequency Factor ◽  
Activation Energies ◽  
Recombination Reaction ◽  
Limited Data ◽  
Kcal Mole ◽  
Fluorinated Radical

The reactions of C2F5 radicals, produced by the photolysis of (C2F5)2CO, with methane and hydrogen have been studied. Assuming zero activation energy for 2C2F5 → C4F10 the activation energies for C2F5 + CH4 → C2F5H + CH3 and C2F5 + H2 → C2F5H + H are 10.6 kcal/mole and 11.9 kcal/mole respectively. The present results have been correlated with data on the reactions of CF3, C3F7, and CH3 radicals with H2, D2, CH4, and C2H6. Taking Erecombination ≈ 0 in all cases and assuming the frequency factor for the recombination reaction varies little from radical to radical, the order of ease of hydrogen abstraction from a given substrate is CF3 > C2F5 > C3F7 > CH3. Similarly the ease of hydrogen abstraction from a substrate by a given fluorinated radical is C2H6 > H2 > CH4 > D2. A calculation based on very limited data indicates the reaction CH3 + C2F5COC2F5 → CH3COC2F5 + C2F5 may occur with an activation energy of approximately 7 kcal/mole.

THE ABSTRACTION OF HYDROGEN ATOMS FROM AMINES AND RELATED COMPOUNDS

1960 ◽  
Vol 38 (8) ◽  
pp. 1339-1345 ◽  
Author(s):  
R. K. Brinton
Keyword(s):  
Reaction Rates ◽  
Activation Energies ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Temperature Range ◽  
Exponential Factors ◽  
Related Compounds

The reaction of methyl radicals with a group of amines and amine-like compounds has been investigated in the temperature range 125° to 157 °C. The abstraction activation energies of hydrogen atoms from these compounds, the corresponding pre-exponential factors, and the actual reaction rates indicate that the N—H hydrogen atoms are more labile than the C—H atoms in these compounds.

Reactions of Methyl Radicals. II. Hydrogen Abstraction from Methyl Trifluoroacetate

1979 ◽  
Vol 32 (5) ◽  
pp. 1025 ◽  
Author(s):  
NL Arthur ◽  
PJ Newitt
Keyword(s):  
Rate Constants ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Methyl Radicals ◽  
Temperature Range ◽  
Cf3 Radical

Hydrogen abstraction from CF3COOCH3 and CH3COCH3 by CH3 radicals CF3 + CF3COOCH3 → CH4 + CF3COOCH2 (1) CF3 + CF3COOCH3 → CH4 + CH3COCH2 (3) has been studied in the temperature range 117-244�. The rate constants, based on the value of 1013.34 cm3 mol-1 s-1 for the recombination of CH3 radicals, are given by (k in cm3 mol-1 s-1 and E in J mol-1) : logk1 = (10.39 � 0.11)- (37680 � 880)/19.145T logk3 = (11.53 � 0.02)- (40590 � 170)/19.145T CF3COOCH3 is less susceptible to attack by CH3 radicals than by CF3 radicals by a factor of 2.8 at 400 K, due mainly to a difference in A factors, since the activation energies of the two reactions are almost identical. These results can be rationalized in terms of intermolecular polar repulsion between the CF3 radical and CF3COOCH3.

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