THE RATE OF REACTION OF ACTIVE NITROGEN WITH ETHANE, PROPANE, AND NEOPENTANE

1964 ◽  
Vol 42 (8) ◽  
pp. 1948-1956 ◽  
Author(s):  
W. E. Jones ◽  
C. A. Winkler
Keyword(s):  
Rate Constants ◽  
Reaction Times ◽  
Reactive Species ◽  
Hydrogen Atoms ◽  
Active Nitrogen ◽  
Probe Technique ◽  
Temperature Range ◽  
Excited Species ◽  
Rate Of Reaction ◽  
Dual Activation

The reactions of active nitrogen with ethane, propane, and neopentane have been studied over the temperature range 0 to 450 °C. A cobalt probe technique was used to stop the reactions after various reaction times. Second order rate constants have been calculated on the assumption that nitrogen atoms are the only reactive species in active nitrogen. Broken Arrhenius lines were obtained for both the ethane and neopentane reactions but this behavior was not observed with the propane reaction. The dual activation energies have been attributed to a mechanism involving initiation by both excited molecules and either nitrogen or hydrogen atoms. Methods are outlined by which an estimate has been made of the concentration of excited species assumed to be involved in the ethane reaction.

THE REACTIONS OF ACTIVE NITROGEN WITH THE BUTANES

1954 ◽  
Vol 32 (7) ◽  
pp. 718-724 ◽  
Author(s):  
R. A. Back ◽  
C. A. Winkler
Keyword(s):  
Nitrogen Atom ◽  
Rate Constants ◽  
Hydrogen Cyanide ◽  
Main Product ◽  
Activation Energies ◽  
Reactive Species ◽  
Atomic Nitrogen ◽  
Initial Attack ◽  
Active Nitrogen ◽  
Rate Controlling Step

The main product of the reactions of active nitrogen with n- and iso-butanes at 75 °C. and 250 °C. was hydrogen cyanide. Small amounts of C2 hydrocarbons, mainly ethylene and acetylene, were produced in both reactions. Second order rate constants were calculated on the assumption that the reactive species in active nitrogen is atomic nitrogen, and that the initial attack of a nitrogen atom is the rate-controlling step. The activation energies were then estimated to be 3.6 kcal. and 3.1 kcal. and the probability factors 4.5 × 10−4 and 4.4 × 10−4, for the n-butane and isobutane reactions respectively.

THE RATE OF REACTION OF ACTIVE NITROGEN WITH AMMONIA AND ETHYLENE

1962 ◽  
Vol 40 (1) ◽  
pp. 5-14 ◽  
Author(s):  
A. N. Wright ◽  
C. A. Winkler
Keyword(s):  
Gas Phase ◽  
Rate Constant ◽  
Reaction Times ◽  
Active Nitrogen ◽  
Atom Concentration ◽  
Initial Flow ◽  
Flow Rates ◽  
Average Value ◽  
Rate Of Reaction ◽  
Excited Nitrogen

The rate constants for the reactions of C2H4 and NH3 are determined by termination of the reactions in the gas phase after different times of reaction. The average value for the rate constant of the N atom–C2H4 reaction at 150 °C is 1.8 × 1010 cc mole−1 sec−1, when the initial N-atom concentration is determined from the maximum production of HCN. The average value for the rate constant for the over-all reaction of NH3 with excited nitrogen molecules, at 104 °C in the "poisoned" system, and 83 °C in the "unpoisoned" system, for low initial flow rates of NH3, or short reaction time, is 2.2 × 1010 cc mole−1 sec−1. The decrease in value of this rate constant at higher initial flow rates of NH3 and longer reaction times in the "poisoned" system indicates that the species responsible for NH3 decomposition is generated during the decay of N atoms in the presence of NH3. The value for the NH3 reaction is discussed in terms of energy transfer.

The reaction of hydrogen atoms with propylene

1971 ◽  
Vol 324 (1559) ◽  
pp. 433-446 ◽  
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Flow System ◽  
Primary Process ◽  
Absolute Rate ◽  
Hydrogen Atoms ◽  
Vibrationally Excited ◽  
Flow Rates ◽  
Detailed Mechanism ◽  
Excited Species

A detailed study has been made of the products of the reaction of hydrogen atoms with propylene. A discharge-flow system at 290±3 K was used. Total pressures in the range 4 to 16 Torr (550 to 2200 N m -2 ) of argon were used and the flow rates of hydrogen atoms and propylene ranged individually up to about 12 μ mol s -1 . As found by others the main products are methane, ethane, ethylene, propane and isobutane. Trivial amounts of 2,3-dimethylbutane, but no n-butane, were detected. A detailed mechanism accounting adequately for the reaction is proposed. It is confirmed that formation of the vibrationally excited species, i-C 3 H 7 *, is the predominant primary process. Novel processes which are shown to be important are H+i-C 3 H 7 * → CH 3 +C 2 H 5 and, C 3 H 8 * → CH 4 +C 2 H 4 . A number of rate constant ratios have been evaluated from the data and these allow calculation of absolute rate constants of some individual reactions. The agreement with previously reported values is, in most instances, good.

The reaction of hydrogen atoms with isobutene

1971 ◽  
Vol 324 (1559) ◽  
pp. 447-458 ◽  
Keyword(s):  
Rate Constants ◽  
Reaction System ◽  
Primary Process ◽  
Absolute Rate ◽  
Hydrogen Atoms ◽  
Vibrationally Excited ◽  
Flow Rates ◽  
Detailed Mechanism ◽  
Product Distributions ◽  
Excited Species

A detailed study has been made of the products of the reaction of hydrogen atoms with isobutene in a discharge flow reaction system at 290±3 K. Total pressures in the range 4 to 12 Torr (550 to 1650 N m -2 ) of argon were used and flow rates of hydrogen atoms and isobutene ranged individually up to about 10 μ mol s -1 . The main products were methane, ethane, ethylene, propane, propylene, isobutane and neopentane. A detailed mechanism accounting adequately for the observed product distributions and their dependence upon pressure and reactant mixture composition is proposed. The formation of the vibrationally excited species t-C 4 H 9 * is shown to be the predominant primary process. A number of rate constant ratios have been evaluated and absolute rate constants for some individual reactions have been estimated from the data. Some of the details of an earlier analogous study of the reaction of hydrogen atoms with propylene have been confirmed and some interesting correlations are indicated.

Mechanism and rate parameters for the pyrolysis of 2,3-dimethylbutane

1975 ◽  
Vol 342 (1629) ◽  
pp. 259-277 ◽  
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Rate Constants ◽  
Previous Measurement ◽  
Hydrogen Atoms ◽  
Differential Activation ◽  
Temperature Range ◽  
Thermochemical Calculation

The pyrolysis of 2,3-dimethylbutane (DMB) was investigated in the ranges of 667-770K and 10-181 Torr (1.3-24kPa) at up to 3% decomposition. A Rice-Herzfeld chain terminated by recombinations of methyl and isopropyl radicals is postulated with self-inhibition due to the abstraction of hydrogen atoms from the major olefin product, 2-methyl-2-butene (2M2B), giving resonance-stabilized 2-methyl-2-butenyl radicals which participate in termination reactions. DMB---- >2i-C 3 H 7 (1a) DMB----> CH 3 + C 5 H 11 (1b) can be represented for the temperature range investigated, by k 1 = k 1a + k 1b — 10 16.7 exp ( — 322 kj mol -1 / RT ) s -1 which is in agreement with a previous measurement, with thermochemical calculation and with the results of the present investigation. The values of the ratios of rate constants for the reactions i-C 3 H 7 — -►H + C 3 H 6 (3a) i-C 3 H 7 — —> CH 3 + C 2 H 4 (3b) 2,3-dimethylbutyl —->i-C 3 H 7 + C 3 H 6 (5a) 2,3-dimethylbutyl ——> CH 3 + 3-methyl-1-butene (5b) are estimated to be k 3b / k 3a = 0.040 and k 5a / k 5a = 55.6, independent of temperature. The values of the rate constants for the reactions CH 3 + DMB----> CH 4 + C 6 H 13 (7) i-C 3 H 7 + DMB -> C 3 H 8 + C 6 H 13 (4) CH 3 + 2M2B -> CH 4 + C 5 H 9 (12) are estimated to be k 7 = 10 13.3 exp ( — 60 kJ mol -1 / RT ) cm 3 mol -1 s -1 , k 4 = 10 13.2 exp (— 89 kJ mol -1 / RT ) cm 3 mol -1 s -1 , and, k 12 = 10 13.7 exp (— 63 k J mol -1 / RT ) cm 3 mol -1 s -1 . The differential activation energy for abstraction of primary/tertiary hydrogen atoms from DMB is found to be 21 k J mol -1 . The results confirm also the value 10 11.6 cm 3 mol -1 s -1 for the rate constant of the mutual recombination of isopropyl radicals.

The Temperature Dependence of the Ratio kd/kc for Ethyl Radicals

1975 ◽  
Vol 53 (8) ◽  
pp. 1237-1244 ◽  
Author(s):  
D. G. Hooper ◽  
M. Simon ◽  
M. H. Back
Keyword(s):  
Liquid Phase ◽  
Transition State ◽  
Gas Phase ◽  
Rate Constants ◽  
Low Temperatures ◽  
Experimental Error ◽  
Hydrogen Atoms ◽  
Direct Photolysis ◽  
Temperature Range ◽  
Ethyl Radicals

The ratio of the rate constants for disproportionation and combination for ethyl radicals, kd/kc[Formula: see text]has been measured over the temperature range 298–173 K in the gas phase. Ethyl radicals were produced by direct photolysis of ethylene followed by addition of hydrogen atoms to ethylene. At low temperatures the only important reactions of the radicals were combination and disproportionation. The ratio kd/kc was obtained from measurements of the rates of formation of ethane, butane, and butene. No change in the ratio kd/kc was observed over the temperature range studied, leading to the conclusion that Ed − Ec = 0, within the experimental error. The significance of this result is discussed in relation to other measurements in both gas and liquid phase and to the nature of the transition state for this reaction.

THE REACTIONS OF ACTIVE NITROGEN WITH METHANE AND ETHANE

1956 ◽  
Vol 34 (10) ◽  
pp. 1457-1463 ◽  
Author(s):  
P. A. Gartaganis ◽  
C. A. Winkler
Keyword(s):  
Hydrogen Atom ◽  
Flow Rate ◽  
Hydrogen Cyanide ◽  
Induction Effect ◽  
Hydrogen Atoms ◽  
Active Nitrogen ◽  
Temperature Range ◽  
Methane Flow Rate ◽  
Methane Flow

Reinvestigation of the active nitrogen – methane reaction in the temperature range 45° to 500 °C. has confirmed hydrogen cyanide as the only product, other than hydrogen, formed in measurable amounts. An “induction” effect in the hydrogen cyanide production was observed with increase of methane flow rate. This induction decreased with increase of temperature and was shown to be due to concomitant hydrogen atom reactions, since it could be eliminated by addition of hydrogen atoms to the reaction mixture. Reinvestigation of the active nitrogen – ethane reaction over the temperature range −100° to 475 °C. also confirmed hydrogen cyanide to be the only measurable product, other than hydrogen, of that reaction. There was some indication that an induction effect was present with ethane, as with methane, and it may be concluded tentatively that both reactions are carried substantially by hydrogen atom reactions.

Critical Review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (⋅OH/⋅O− in Aqueous Solution

1988 ◽  
Vol 17 (2) ◽  
pp. 513-886 ◽  
Author(s):  
George V. Buxton ◽  
Clive L. Greenstock ◽  
W. Phillips Helman ◽  
Alberta B. Ross
Keyword(s):  
Aqueous Solution ◽  
Hydroxyl Radicals ◽  
Rate Constants ◽  
Critical Review ◽  
Hydrogen Atoms ◽  
Hydrated Electrons

Deactivation of O(1S) and O2(b1Σg+)

1969 ◽  
Vol 47 (10) ◽  
pp. 1870-1877 ◽  
Author(s):  
F. Stuhl ◽  
K. H. Welge
Keyword(s):  
Rate Constants ◽  
Excited Species ◽  
Intensity Decay

Rate constants for the collisional deactivation of O(1S) and O2(b1Σg+) are reported. They are obtained by measuring the intensity decay of the O(1S → 1D) and O2(b1Σg+ → X2Σg+) emissions after a pulsed production of the excited species.

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