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 - 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.

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 KINETICS OF THE DECOMPOSITION REACTIONS OF THE LOWER PARAFFINS: IV. THE ROLE OF FREE RADICALS IN THE DECOMPOSITION OF n-BUTANE

1939 ◽  
Vol 17b (3) ◽  
pp. 105-120 ◽  
Author(s):  
E. W. R. Steacie ◽  
H. O. Folkins
Keyword(s):  
Nitric Oxide ◽  
Ethylene Oxide ◽  
Complete Suppression ◽  
Radical Chain ◽  
Decomposition Reactions ◽  
Maximum Inhibition ◽  
A Chain ◽  
Kinetics Of ◽  
Oxide Inhibition

An investigation has been made of the inhibition of free radical chain processes in the decomposition of n-butane by the addition of nitric oxide. The method was to initiate chains in butane at low temperatures by means of ethylene oxide, and then to investigate the efficiency of nitric oxide in suppressing these chains.It was found that nitric oxide is not completely efficient as a chain breaker, inasmuch as sensitization by ethylene oxide persisted in the presence of large amounts of nitric oxide. It is therefore concluded that maximum inhibition of organic decomposition reactions by nitric oxide does not in all cases correspond to complete suppression of chains, and hence the real chain length in such reactions may be greater than that inferred from the results of the nitric oxide inhibition method.

The thermal decomposition of aromatic compounds - II. Dichlorobenzenes

1954 ◽  
Vol 224 (1159) ◽  
pp. 544-551 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Thermal Stabilities ◽  
Carbonaceous Deposit ◽  
Chain Processes ◽  
Composition And Structure ◽  
Gaseous Decomposition Product ◽  
Molecular Reaction ◽  
Complete Exclusion ◽  
The Stability ◽  
Kinetic Features

A kinetic study of the thermal decomposition of the dichlorobenzenes shows that the three isomers behave similarly. The compounds differ strikingly from chlorobenzene, inasmuch as the rate of decomposition is not reduced by nitric oxide or ammonia. Other kinetic features suggest that the reaction is unimolecular, and that chain processes do not occur to an appreciable extent. The main gaseous decomposition product is hydrogen chloride, and nearly all the combined chlorine can be accounted for as this product. Very small amounts of gaseous hydrogen are also found, but the balance of the combined hydrogen remains in the carbon deposited on the walls of the reaction vessel; this carbonaceous deposit is of similar composition and structure to that formed from chlorobenzene. Comparison of the thermal stabilities of benzene, chlorobenzene and the dichlorobenzenes shows that the stability is dependent on the extent of substitution of the aromatic ring but is little influenced by the relative positions of the substituents. The increased rate of decomposition caused by a second chlorine atom is evidently due to its ability to facilitate a molecular reaction, which apparently operates to the complete exclusion of chain processes.

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.

Thermal decomposition of barium perchlorate

1969 ◽  
Vol 47 (16) ◽  
pp. 3031-3039 ◽  
Author(s):  
R. J. Acheson ◽  
P. W. M. Jacobs
Keyword(s):  
Thermal Decomposition ◽  
Ambient Pressure ◽  
Barium Chloride ◽  
Reaction Sequence ◽  
Chain Reaction ◽  
Gaseous Products ◽  
A Chain ◽  
Two Stages ◽  
Linear Period ◽  
Barium Perchlorate

The thermal decomposition of anhydrous barium perchlorate to barium chloride and oxygen has been studied by pressure measurements, or by weight loss, in vacuo, under the accumulated gaseous products (0–3 Torr oxygen), under dry air or nitrogen, and mixed with added barium chloride. The plots of fractional decomposition (α) against time (t) are complex, as would be expected for a reaction proceeding via unstable intermediates. The most pronounced features of the α(t) curves are an initial acceleratory period, which is succeeded by an approximately linear period and then, after a sharp break (reduction in rate), by a deceleratory period which conforms to the contracting-volume kinetic law. The latter stage is associated with the decomposition of barium chlorate and has an activation energy of 59 kcal/mole. The first two stages comprise the decomposition of perchlorate to chlorate with the approximate stoichiometry 3ClO4− = 2ClO3− + Cl− + 3O2. A chain reaction sequence, which involves O atoms as chain carriers, is proposed for these stages. The effect of the removal of products, of increasing the ambient pressure of inert gas, and of the addition of barium chloride, can all be explained on this model.

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.

Cracking of squalene into isoprene as chemical utilization of algae oil

2020 ◽  
Vol 22 (10) ◽  
pp. 3083-3087
Author(s):  
Kazuya Kimura ◽  
Kazuma Shiraishi ◽  
Takahiro Kondo ◽  
Junji Nakamura ◽  
Tadahiro Fujitani
Keyword(s):  
Thermal Decomposition ◽  
Chain Reaction ◽  
Algae Oil ◽  
A Chain ◽  
Chemical Utilization

Thermal decomposition of squalene proceeds as a chain reaction to produce isoprene (C5H8) and C10 hydrocarbons.

FREE RADICAL MECHANISMS FOR INHIBITED ORGANIC DECOMPOSITIONS

1960 ◽  
Vol 38 (7) ◽  
pp. 1027-1034 ◽  
Author(s):  
B. W. Wojciechowski ◽  
K. J. Laidler
Keyword(s):  
Nitric Oxide ◽  
Free Radical ◽  
Hydrogen Atom ◽  
Molecular Mechanisms ◽  
Rate Equations ◽  
Nitric Oxide Inhibition ◽  
A Chain ◽  
Oxide Inhibition

It is suggested that organic decompositions that are fully inhibited by substances such as nitric oxide and propylene proceed not by molecular mechanisms, but by special types of free radical mechanisms in which the inhibitor is involved in both initiation and termination. In the case of nitric oxide inhibition, initiation is considered to be by the abstraction of a hydrogen atom by NO, while termination involves reaction between the most plentiful chain carrier and either HNO or NO, depending upon whether or not H is a chain carrier. Specific mechanisms are proposed for the decompositions of paraffins, ethers, and aldehydes, when inhibited by nitric oxide, and the resulting rate equations are shown to be consistent with the behavior observed experimentally. It is shown for the ethane decomposition that the same limiting rate is obtained for any inhibitor that can become involved in the same type of mechanism.

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