Kinetics of the reaction C2H5 + H2 → C2H6 + H from 1111-1200 K

1982 ◽  
Vol 60 (24) ◽  
pp. 3039-3048 ◽  
Author(s):  
J.-R. Cao ◽  
M. H. Back
Keyword(s):  
Rate Constant ◽  
Equilibrium Concentration ◽  
Reverse Reaction ◽  
Elementary Reaction ◽  
Hydrogen Atoms ◽  
Temperature Range ◽  
Lower Temperature ◽  
Kinetics Of ◽  
Rate Controlling Step ◽  
Hydrogenation Of Ethylene

A system for the measurement of the rate constant for the elementary reaction[Formula: see text]in the temperature range 1111–1200 K is described and is based on the thermal production of an equilibrium concentration of hydrogen atoms. In a mixture of hydrogen with about 10 ppm ethylene this reaction is the rate-controlling step in the hydrogenation of ethylene. The product ethane undergoes rapid secondary dissociation and the final product is methane. The values obtained in the present work, which are represented by the following expression,[Formula: see text](R = 1.987 cal mol−1 deg−1) are compared to those obtained at lower temperature (820–350 K) and to those calculated from measurements of the reverse reaction.

Kinetics of the reaction H + C2H6 → H2 + C2H5 in the temperature region of 1000 K

1984 ◽  
Vol 62 (1) ◽  
pp. 86-91 ◽  
Author(s):  
J.-R. Cao ◽  
M. H. Back
Keyword(s):  
Equilibrium Constant ◽  
Rate Constant ◽  
Temperature Region ◽  
Recent Measurement ◽  
Hydrogen Atoms ◽  
Elementary Reactions ◽  
Temperature Range ◽  
Hydrogen Molecules ◽  
Kinetics Of ◽  
Rate Controlling Step

A system for the measurement of rate constants for elementary reactions of hydrogen atoms in the temperature region of 1000 K is described. The concentration of hydrogen atoms is controlled by the equilibrium constant for dissociation of hydrogen molecules. The kinetics of the rate of conversion of ethane to ethylene in this system has been studied over the temperature range 876–1016 K. The results show that the rate-controlling step is[Formula: see text]and the value obtained for the rate constant is[Formula: see text](R = 1.987 cal mol−1 deg−1). This value is compared with values obtained from other methods over the temperature range 300–1400 K. Combination with a recent measurement of the rate constant for the reverse reaction yields an experimental value for the equilibrium constant for the reaction.

Reactions of hydrogen atoms with hexafluoroacetone

1978 ◽  
Vol 56 (20) ◽  
pp. 2638-2645 ◽  
Author(s):  
D. W. Grattan ◽  
K. O. Kutschke
Keyword(s):  
Rate Constant ◽  
Cross Sections ◽  
The Other ◽  
Hydrogen Atoms ◽  
Kinetics Of

Attempts were made to study the kinetics of the reaction of atomic H with (CF3)2CO vapour (HFA). Atomic H was generated from H2 by mercury photosensitization in the presence of C2H4 and HFA but the system was complicated by the loss of C2H5 radicals by addition to HFA and the kinetic results were intractable. When atomic H was generated from C3H8, the kinetics again were obscured by some unidentified reaction(s) which became more important at higher [HFA]/[C3H8]. An estimate of the rate constant for the addition of H to HFA obtained at low [HFA]/[C3H8] yielded k9 = 8.5 × 105 l mol−1 s−1. Trifluoroacetaldehyde was identified with some reliability but many of the other heavier products formed in the H2 + HFA reaction could not be identified. Quenching cross-sections were determined for C2H4, C3H8, C4H10, and HFA relative to that for N2O.

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.

scholarly journals Kinetic and spectrophotometric studies on the renaturation of deoxyribonucleic acid

1968 ◽  
Vol 109 (4) ◽  
pp. 543-557 ◽  
Author(s):  
K. J. Thrower ◽  
A. R. Peacocke
Keyword(s):  
Ionic Strength ◽  
Rate Constant ◽  
Base Pairs ◽  
Phage Dna ◽  
Dna Strands ◽  
Entropy Of Activation ◽  
T7 Phage ◽  
Kinetics Of ◽  
Rate Controlling Step ◽  
Adenine Thymine

The kinetics of the renaturation of Escherichia coli DNA in 0·4–1·0m-sodium chloride at temperatures from 60° to 90° have been studied. The extent of renaturation was a maximum at 65° to 75° and increased with ionic strength, and the rate constant increased with both ionic strength and temperature. The energy and entropy of activation of renaturation were calculated to be 6–7kcal.mole−1 and −40cal.deg.−1mole−1 respectively. It has been shown that renaturation is a second-order process for 5hr. under most conditions. The results are consistent with a reaction in which the rate-controlling step is the diffusion together of two separated complementary DNA strands and the formation of a nucleus of base pairs between them. The kinetics of the renaturation of T7-phage DNA and Bordetella pertussis DNA have also been studied, and their rates of renaturation related quantitatively to the relative heterogeneity of the DNA samples. By analysis of the spectra of DNA at different stages during renaturation it was shown that initially the renatured DNA was rich in guanine–cytosine base pairs and non-random in base sequence, but that, as equilibrium was approached, the renatured DNA gradually resembled native DNA more closely. The rate constant for the renaturation of guanine–cytosine base pairs was slightly higher than for adenine–thymine base pairs.

scholarly journals The rupture of carbon-nitrogen bonds. Kinetics of the thermal decomposition of ω-azotoluene vapour

1936 ◽  
Vol 156 (888) ◽  
pp. 455-462 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Energy Of Activation ◽  
Azo Compounds ◽  
Temperature Range ◽  
The Difference ◽  
Lower Temperature ◽  
Nitrogen Bonds ◽  
Kinetics Of

The energy of activation found for the benzalazine decomposition is somewhat higher than those hitherto recorded for the decompositions of azo-compounds. The difference between the azine- and azo-decompositions can only be appreciated, however, on comparing the decomposition of benzalazine with that of its aromatic azo-analogue, i . e ., ω-azotoluene. According to Thiele,* when the latter substance is heated in vacuo , gas liberation begins at 15°-180° C. C 6 H 5 . CH 2 ─ N = N ─ CH 2 . C 6 H 5 = N 2 + C 6 H 5 . CH 2 . CH 2 . C 6 H 5 . This reaction is analogous to the benzalazine decomposition (measured at 318°- 180° C), C 6 H 5 . CH = N ─ N = CH. C 6 H 5 = N 2 + C 6 H 5 . CH = CH. C 6 H 5 , and resembles the aliphatic azo-decompositions investigated by Rams-perger over the temperature range 250° - 350° C, though occurring at a lower temperature than these.

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

1976 ◽  
Vol 29 (7) ◽  
pp. 1483 ◽  
Author(s):  
NL Arthur ◽  
M Lee
Keyword(s):  
Free Radicals ◽  
Rate Constant ◽  
Rate Constants ◽  
Hydrogen Abstraction ◽  
Reverse Reaction ◽  
Thermochemical Data ◽  
Methyl Radicals ◽  
Dimethyl Sulphide ◽  
Temperature Range

Hydrogen abstraction from (CH3),S and CH3COCH3 by CH3 radicals CH3+CH3SCH3 → CH4+CH3SCH2 CH3 + CH3COCH3 → CH4 + CH3COCH2 has been studied in the temperature range 120-245�. The rate constants, based on the value of 1013.34cm3 mol-l s-1 for the recombination of CH3 radicals, are given by (k in cm3 mol-1 s-1, E in kJ mol-1, R = 0.008314 kJ K-1 mol-1): logk1 = (11.62 � 0.08) ? (38.35 � 0.68)/2.303RT logk3 = (11.61 � 0.05) ? (40.48 � 0.46)/2.303RT Combination of the results for (1) with thermochemical data gives a calculated value of Logk-1 = (11.8 -63.7/2.303RT for the rate constant of the reverse reaction. The results for CH3+(CH3)2S are compared with all of the available data for hydrogen abstraction by free radicals from both sulphur-containing compounds, and molecules of the type (CH3)xM.

KINETICS OF THE ABSTRACTION OF HYDROGEN ATOMS FROM HYDROGEN SULFIDE BY TRIFLUOROMETHYL RADICALS

1966 ◽  
Vol 44 (12) ◽  
pp. 1445-1449 ◽  
Author(s):  
N. L. Arthur ◽  
T. N. Bell
Keyword(s):  
Hydrogen Sulfide ◽  
Rate Constant ◽  
Hydrogen Sulphide ◽  
Hydrogen Atoms ◽  
Kinetics Of

Trifluoromethyl radicals generated from the photolysis of hexafluoroacetone abstract hydrogen atoms from hydrogen sulphide.[Formula: see text]The rate constant of this reaction measured by comparing the rate with that for the recombination of trifluoromethyl radicals (k = 2.3 × 1013 cc mole−1 s−1) is given by,[Formula: see text]

THE HYDROGEN ISOTOPE EFFECTS IN THE PYROLYSIS OF ETHYL-1,1,2,2-d4 BROMIDE AND OF ETHYL-d5 BROMIDE

1962 ◽  
Vol 40 (8) ◽  
pp. 1533-1539 ◽  
Author(s):  
Arthur T. Blades ◽  
P. W. Gilderson ◽  
M. G. H. Wallbridge
Keyword(s):  
Isotope Effect ◽  
Rate Constant ◽  
Hydrogen Isotope ◽  
Relative Rate ◽  
Isotope Effects ◽  
Side Reaction ◽  
Relative Rate Constant ◽  
Temperature Range ◽  
Rate Controlling Step ◽  
Constant Expression

The relative rate constant expression has been obtained for the decomposition of ethyl-1,1,2,2-d4 bromide under inhibiting conditions in the temperature range 697.6 to 999.1 °K,[Formula: see text]The pressure dependence of the isotope effect has been investigated both with and without inhibitor, and in each case it has been shown that the isotope effect increases with decreasing pressure.The relative rate constant expression for the ethyl-h5, ethyl-d5 bromide comparison was also obtained in the temperature range 730.9 to 964.8 °K,[Formula: see text]The isotope effect is again pressure dependent, falling to lower values as the pressure is decreased.The data are used to demonstrate that the inhibited decomposition of ethyl bromide is primarily a molecular process, and that the rate-controlling step involves a carbon–hydrogen bond break.A side reaction that produces small amounts of ethane has been observed.

KINETICS OF THE REACTION H + CH4 = CH3 + H2

1954 ◽  
Vol 32 (7) ◽  
pp. 650-659 ◽  
Author(s):  
M. R. Berlie ◽  
D. J. Le Roy
Keyword(s):  
Rate Constant ◽  
Methyl Radical ◽  
Temperature Range ◽  
Kinetics Of

The reaction H + CH4 = CH3 + H2 has been studied in the temperature range 99° to 163 °C. The rate constant is given by the expression k = 1.7 × 10−14 exp (−4500/RT). The data are in agreement with the results, but not the interpretations, of previous work. The entropy of the methyl radical has been calculated for several temperatures.

Halogenation with N-haloamines in strong acids. II. Kinetics and rate constants

1970 ◽  
Vol 48 (4) ◽  
pp. 554-560 ◽  
Author(s):  
J. Spanswick ◽  
K. U. Ingold
Keyword(s):  
Rate Constant ◽  
Decanoic Acid ◽  
Propagation Rate ◽  
The Self ◽  
Radical Chain ◽  
Rate Of Reaction ◽  
Propagation Rate Constant ◽  
Strong Acids ◽  
Kinetics Of ◽  
Rate Controlling Step

The kinetics of the radical chain chlorination of decanoic acid by N-chlorodimethylamine and N-chloropiperidine in 2 and 4 M H2SO4 in acetic acid have been examined at 30°. The rate of reaction is proportional to the decanoic acid concentration and to the square root of the rate of chain initiation. The rate controlling step for propagation involves the attack of an aminium radical on decanoic acid, and termination involves the self-reaction of two aminium radicals. The latter reaction may involve the prior, rapid deprotonation of one or both radicals. The propagation rate constant has been estimated to be in the range 7 × 102 to 1 × 104 M−1 s−1 and the termination rate constant to be in the range 6 × 106 to 5 × 107 M−1 s−1.

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