THE KINETICS OF THE THERMAL DECOMPOSITION OF DISULPHUR DECAFLUORIDE

1951 ◽  
Vol 29 (6) ◽  
pp. 508-525 ◽  
Author(s):  
W. R. Trost ◽  
R. L. McIntosh
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Heterogeneous Reaction ◽  
Homogeneous Reaction ◽  
Chain Reaction ◽  
First Order ◽  
Reaction Proceeds ◽  
Total Process ◽  
A Chain ◽  
Kinetics Of

The thermal decomposition of the gas disulphur decafluoride has been studied in a metal reactor. Analytical evidence showed that the reaction proceeds according to the equation S2F10 = SF6 + SF4.The reaction was found to be largely homogeneous, as the heterogeneous reaction accounted for less than 5% of the total process. The homogeneous reaction was shown to be first order, and in the temperature range investigated the rate is given by ln k = 47.09 − 49,200/RT. A chain reaction is postulated to explain the observed rate of the reaction. The effect of nitric oxide and acetylene dichloride on the rate and products of the reaction was investigated.

The thermal decomposition of aliphatic aldehydes

1963 ◽  
Vol 276 (1365) ◽  
pp. 278-292 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Chain Reaction ◽  
Chance Coincidence ◽  
Limited Success ◽  
Molecular Reaction ◽  
A Chain ◽  
The Stability ◽  
Oxide Inhibition ◽  
Chain Propagation And Termination

The thermal decomposition of acetaldehyde, propionaldehyde, n -butyraldehyde and iso-butyraldehyde, as investigated by the static method, is essentially homogeneous, inhibitable by propylene, isobutene and small amounts of nitric oxide, and generally catalyzed at high inhibitor concentrations. The kinetic order of the uninhibited decomposition exhibits little obvious regularity, but that of the maximally inhibited reaction is approximately 1.5 for all three inhibitors. Kates of the uninhibited decomposition do not follow the sequence in the homologous series, and there is no systematic variation in the extent of inhibition from one aldehyde to another. For each aldehyde, the minimum rates for the three inhibitors in general are not identical, nevertheless exhibit a correspondence probably close enough to eliminate chance coincidence. The kinetic and analytical results of the uninhibited decomposition can be approximately described by a Kice-Herzfeld-type mechanism, with the kinetics in each case largely determined by the stability of radicals and their reactions in chain propagation and termination. The question whether the maximally inhibited reaction is a molecular reaction or a chain reaction is surveyed. Although the results cannot be completely accounted for by a molecular reaction alone, a chain mechanism for propylene inhibition involving allyl radicals likewise has only limited success. For nitric-oxide inhibition, it is not certain how far the results are affected by the occurrence of the subsequent catalyzed reaction. No definite conclusion can thus be reached about the nature of the maximally inhibited reaction.

The kinetics of the thermal decomposition of normal paraffin hydrocarbons II. Comparative measurements on the series from propane to n -decane

1950 ◽  
Vol 201 (1064) ◽  
pp. 18-26 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
High Pressures ◽  
Single Mode ◽  
Second Order ◽  
Chain Reaction ◽  
Molecular Rearrangement ◽  
Normal Paraffin ◽  
Rearrangement Process ◽  
Kinetics Of

The rates of the nitric oxide-inhibited decompositions of hydrocarbons in the series propane to n -decane (which according to the results of Part I represent the chain-free molecular reactions) have been measured over a range of pressures. As inferred from the 'apparent chain length' the molecular rearrangement process increases in importance relatively to the chain reaction with the ascent of the series, and, for a given hydrocarbon, with increasing pressure. For each hydrocarbon, the order of reaction varies between the first and the second. The results are not consistent with a constant order of 1.5 as has been suggested. Nor is the pressure dependence consistent with the uniform transition from second order to first predicted for unimolecular reactions dependent upon a single mode of activation by collision. There appears to be a contribution to the overall reaction from processes which remain of second order up to high pressures. The decomposition rate for a given hydrocarbon pressure tends to a limit as the series is ascended, for reasons which are discussed.

The kinetics of the thermal decomposition of normal paraffin hydrocarbons - I. The inhibition of chains and the nature of the residual reaction

1950 ◽  
Vol 200 (1063) ◽  
pp. 458-473 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Steady State ◽  
Chain Reaction ◽  
Normal Paraffin ◽  
Residual Rate ◽  
Molecular Reaction ◽  
Kinetics Of ◽  
Limiting Value

The decomposition of paraffin hydrocarbons is lowered to a limiting value by additions of nitric oxide or of propylene. It has been a matter for discussion whether the residual rate corresponds to a molecular reaction or a steady state in which the chain reaction is imperfectly suppressed. Fresh evidence, including the facts that the limiting rates with the two inhibitors are identical, and that extra nitric oxide added during the reaction has no further effect, indicates that the former hypothesis is the more probable.

KINETICS AND MECHANISMS OF THE PYROLYSIS OF DIMETHYL ETHER: II. THE REACTION INHIBITED BY NITRIC OXIDE AND PROPYLENE

1963 ◽  
Vol 41 (8) ◽  
pp. 1993-2008 ◽  
Author(s):  
D. J. McKenney ◽  
B. W. Wojciechowski ◽  
K. J. Laidler
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Dimethyl Ether ◽  
Chain Process ◽  
Maximal Inhibition ◽  
First Order ◽  
Temperature Range ◽  
Maximum Inhibition ◽  
A Chain

The thermal decomposition of dimethyl ether, inhibited by nitric oxide and by propylene, was studied in the temperature range of 500 to 600 °C. About 1.5 mm of nitric oxide gave maximal inhibition, the rate then being approximately 8% of the uninhibited rate. With propylene, approximately 70 mm gave maximal inhibition, the rate being slightly higher than that using nitric oxide (~12.5% of the uninhibited rate). In both cases the degree of inhibition was independent of the ether pressure. In the maximally inhibited regions both reactions are three-halves order with respect to ether pressure. As the pressure of nitric oxide was increased beyond 10–15 mm, the overall rate increased, and in this region the reaction is first order with respect to both nitric oxide and ether. A 50:50 mixture of CH3OCH3 and CD3OCD3, with enough NO to ensure maximum inhibition, was pyrolyzed. Even at very low percentage decomposition the CD3H/CD4 ratio was approximately the same as that in the uninhibited decomposition, proving that the inhibited reaction is largely a chain process. Detailed inhibition mechanisms are proposed in which the inhibitor is involved both in initiation and termination reactions.

Kinetic Studies in the Chemistry of Rubber and Related Materials. II. The Kinetics of Oxidation of Unconjugated Olefins

1947 ◽  
Vol 20 (3) ◽  
pp. 609-617 ◽  
Author(s):  
J. L. Holland ◽  
Geoffrey Gee
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Studies ◽  
Chain Termination ◽  
Low Oxygen ◽  
Chain Reaction ◽  
Kinetics Of Oxidation ◽  
Chain Initiation ◽  
A Chain ◽  
Kinetics Of ◽  
Direct Attack

Abstract A brief review is given of kinetic work on the oxidation of representative mono, 1,4 and 1,5 olefins. The essential process in each case is identified as a chain reaction in which hydrocarbon radicals are formed, absorb oxygen, and then react with another molecule of olefin to give a hydroperoxide and a new free radical. Three methods of chain initiation are considered: (1) direct attack of oxygen on the olefin, (2) thermal decomposition of the hydroperoxide, (3) thermal decomposition of added benzoyl peroxide. Chain termination results from interaction of two free radicals; except at low oxygen pressures, these are both peroxidic.

The kinetics of the thermal decomposition of normal paraffin hydrocarbons III. Activation energies and possible mechanisms of molecular reactions

1950 ◽  
Vol 203 (1075) ◽  
pp. 486-501 ◽  
Keyword(s):  
Nitric Oxide ◽  
Condensation Reaction ◽  
Volume Ratio ◽  
Chain Process ◽  
Normal Reaction ◽  
First Order ◽  
Rate Of Reaction ◽  
Molecular Reaction ◽  
A Chain ◽  
Kinetics Of

In part I it was concluded that the nitric oxide-inhibited decomposition of paraffins probably represents a molecular reaction. Further experiments in which the presence of hydrogen causes a marked increase in the normal reaction but not of the inhibited reaction strengthen this conclusion, by diminishing still further the likelihood that the inhibited reaction is a chain process not suppressible by nitric oxide. Experiments on variation of the surface/volume ratio and on the coating of the vessel surface with potassium chloride have been made for the normal reaction and for the reaction inhibited by nitric oxide and by propylene respectively. The effect of the surface change is either negligible or, in certain cases, to accelerate a condensation reaction* which may vitiate the measurement of the true decomposition rate. Over limited ranges the rate of reaction, r ∞ , is connected with the pressure by the relation r ∞ = Ap 0 + Bp 2 0 , but this is probably an approximation for an expression of the form r ∞ = ap 2 0 /1 + a'p 0 + bp 2 0 /1 + b'p 0 , the reaction mechanism being composite. A reaction nearly of the first order predominates at lower pressures and one nearly of the second order at higher pressures.

scholarly journals The kinetics of the thermal decomposition of acetophenone

1940 ◽  
Vol 176 (967) ◽  
pp. 468-473 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Diethyl Ether ◽  
First Order ◽  
Aldehydes And Ketones ◽  
Kinetics Of ◽  
Subsequent Decomposition

The mechanisms involved in the thermal decomposition of aldehydes and ketones are varied, and the relations between them somewhat complex. In particular, an interesting contrast in behaviour has recently been found between benzaldehyde and acetaldehyde. An investigation of acetophenone has therefore been made for comparison with acetone. The thermal decomposition of acetophenone takes place predominantly by the step C 6 H 5 COCH 3 = C 6 H 5 CH 3 + CO, the toluene undergoing a subsequent decomposition to give chiefly benzene, methane and carbon. It differs from that of acetone in yielding hardly any ketene. It is homogeneous and nearly of the first order, with no sharp falling off in rate at 20 mm . There is no retardation by nitric oxide or by greatly increased surface, nor can an increased rate of decomposition be induced by the presence of radicals from decomposing diethyl ether. This is taken as evidence for the absence of reaction chains. In this respect the behaviour resembles that of acetone, but other differences in kinetics exist. These are briefly discussed.

The kinetics of the thermal decomposition of branched-chain paraffin hydrocarbons - II. The isomeric hexanes

1952 ◽  
Vol 214 (1118) ◽  
pp. 339-343 ◽  
Keyword(s):  
Nitric Oxide ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Order Transition ◽  
First Order ◽  
Single Transition ◽  
Branched Chain ◽  
Kinetics Of ◽  
Constant Activation Energy ◽  
Methyl Pentane

In the study of the thermal decomposition of paraffins the contrast of iso -butane with n -butane and of the branched pentanes with normal pentane has led to the investigation of the isomeric hexanes. The nitric oxide-inhibited reaction of neo -hexane possesses a constant, activation energy at different initial pressures and shows a single transition from second to first order with increasing pressure. The reactions of 2:3-dimethyl-butane, 2-methyl-pentane and 3-methyl-pentane show a double-order transition and a rise in activation energy at lower initial pressures, as previously found for the higher normal paraffins.

scholarly journals Reaction chains in the thermal decomposition of hydrocarbons. A comparison of methane, ethane, propane and hexane

1938 ◽  
Vol 167 (931) ◽  
pp. 447-455 ◽  
Author(s):  
J. E. Hobbs ◽  
Cyril Norman Hinshelwood
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Chain Length ◽  
Homologous Series ◽  
Normal Rate ◽  
Chain Mechanism ◽  
Reaction Proceeds ◽  
Decomposition Of Hydrocarbons ◽  
A Chain

The inhibition by nitric oxide of the thermal decomposition of ethane at 600° shows that the reaction proceeds partly by a chain mechanism, the apparent chain length, as measured by the ratio of the normal rate to that of the chain-free reaction, being of the order 5-15 over the range of pressure 50-500 mm., and falling with increasing pressure (Staveley 1937; Hobbs and Hinshelwood 1938). In passing up a homologous series of compounds the chain length may rise or fall. With the series of ethers, for examples, it decreases rapidly, whereas with the aldehydes it increases (Staveley and Hinshelwood 1937).

THE KINETICS OF THE THERMAL DECOMPOSITIONS OF THE LOWER PARAFFINS: V. THE NITRIC OXIDE INHIBITED DECOMPOSITION OF n-BUTANE

1940 ◽  
Vol 18b (1) ◽  
pp. 1-11 ◽  
Author(s):  
E. W. R. Steacie ◽  
H. O. Folkins
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Free Radical ◽  
High Pressures ◽  
Free Radical Processes ◽  
Temperature Range ◽  
Radical Recombination ◽  
Radical Processes ◽  
Kinetics Of ◽  
Good Agreement

A detailed investigation of the inhibition by nitric oxide of the thermal decomposition of n-butane has been carried out over the temperature range 500° to 550 °C.In all cases it was found that inhibition decreased with increasing butane concentration. This suggests that radical recombination occurs in the normal decomposition by ternary collisions with butane molecules acting as third bodies.The activation energies of the normal and inhibited reactions have been determined. For high pressures the two values are in good agreement, viz., 58,200 and 57,200 cal. per mole respectively. The products of the inhibited reaction were also found to be the same as those of the normal reaction.It is concluded that free radical processes predominate, involving comparatively short chains.

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