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.

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.

Kinetics and mechanisms of the pyrolysis of diethyl ether II. The reaction inhibited by nitric oxide

1964 ◽  
Vol 278 (1375) ◽  
pp. 517-526 ◽  
Keyword(s):  
Nitric Oxide ◽  
Diethyl Ether ◽  
High Pressures ◽  
Radical Reaction ◽  
Free Radical Reaction ◽  
Order Component ◽  
Maximal Inhibition ◽  
First Order ◽  
A Chain ◽  
Low Pressures

The pyrolysis of diethyl ether, inhibited by nitric oxide, was studied in the temperature range of 560 to 640 °C, and at pressures between 10 and 360 mmHg. About 7 mm of nitric oxide gave maximal inhibition. The degree of maximal inhibition varied with the temperature but was independent of the ether pressure. As the nitric oxide pressure was increased beyond 35 to 40 mm the rate increased linearly. In the maximally inhibited region the order with respect to ether varied between 1 at high temperatures and low pressures to 3/2 at low temperatures and high pressures. A chain mechanism is proposed, in which nitric oxide is involved in both initiation and termination, and leads to a rate expression showing both first-order and three-halves-order dependence on ether pressure. The first-order component of the reaction is concluded to consist of both a molecular split into ethanol and ethylene and a free-radical reaction.

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.

The thermal decomposition of diethyl ether. I. Rate-pressure relations

1958 ◽  
Vol 245 (1240) ◽  
pp. 28-39 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Diethyl Ether ◽  
Order Rate Constant ◽  
Inert Gases ◽  
Chain Process ◽  
Chain Reactions ◽  
First Order ◽  
Molecular Reaction ◽  
A Chain ◽  
Reduced Rate

In the thermal decomposition of diethyl ether the first-order rate constant ( k ) varies with the pressure ( p ) of the ether itself, or that of added hydrogen, or that of various chemically inert gases according to a more complex pattern than has hitherto been supposed. In general, k increases approximately linearly with p X over a certain range: the slope of the curve then decreases as though a limit were being approached. When X refers to ether, hydrogen or certain other gases no limit is in fact reached, but k continues to increase at a considerably reduced rate. With certain gases, however, the slope of the curve becomes very small or zero. Changes in k are not explicable by variations in the chemical composition of the products. The forms of the k-p curves are qualitatively similar for the uninhibited reaction (largely a chain process) and for the nitric oxide-inhibited reaction (hypothetical molecular reaction), but the effects are quantitatively quite different. The k-p relations for the molecular reaction conform to those recently established for the decomposition of paraffins and of nitrous oxide, and may possibly be interpreted by the extended theory of unimolecular reactions proposed for these examples. The relations for the chain reactions are more complicated but the interpretation probably includes considerations similar to the above, applied to the initial molecular process by which the chains start.

Consecutive reactions in the thermal decomposition of phenylalkyldiazirines

1977 ◽  
Vol 55 (20) ◽  
pp. 3596-3601 ◽  
Author(s):  
Michael T. H. Liu ◽  
Barry M. Jennings
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Diazo Compounds ◽  
First Order ◽  
Temperature Range ◽  
Decomposition Reactions ◽  
Consecutive Reactions ◽  
Rate Processes ◽  
Subsequent Decomposition

The thermal decomposition of phenyl-n-butyldiazirine and of phenylmethyldiazirine in DMSO and in HOAc have been investigated over the temperature range 80–130 °C. The intermediate diazo compounds, 1-phenyl-1-diazopentane and 1-phenyldiazoethane respectively have been detected and isolated. The decomposition of phenyl-n-butyldiazirine and the subsequent decomposition of its product, 1-phenyl-1-diazopentane, are an illustration of consecutive reactions. The kinetic parameters for the isomerization and decomposition reactions have been determined. The isomerization of phenylmethyldiazirine to 1-phenyldiazoethane is first order and probably unimolecular but the kinetics for the subsequent reactions of 1-phenyldiazoethane are complicated by several competing rate processes.

Influence of Nitric Oxide on the Thermal Decomposition of Dimethyl Ether. Gaseous Catalysis

Nature ◽  
1936 ◽  
Vol 138 (3491) ◽  
pp. 546-547 ◽  
Author(s):  
P. F. GAY ◽  
MORRIS W. TRAVERS
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Dimethyl Ether

THE THERMAL DECOMPOSITION OF PERACETIC ACID IN AROMATIC SOLVENTS

1963 ◽  
Vol 41 (7) ◽  
pp. 1826-1831 ◽  
Author(s):  
F. W. Evans ◽  
A. H. Sehon
Keyword(s):  
Thermal Decomposition ◽  
Rate Constant ◽  
Peracetic Acid ◽  
First Order ◽  
Aromatic Solvents ◽  
Temperature Range ◽  
Polymeric Compounds

The thermal decomposition of peracetic acid in toluene, benzene, and p-xylene was studied over the temperature range 75–95°C. The main products of decomposition were found to be CH4, CO2, CH3COOH; small amounts of methanol, phenols, and polymeric compounds were also detected.The rate of the overall decomposition was first order with respect to peracetic acid, and the results could be explained by postulating the participation of the two simultaneous reactions:[Formula: see text] [Formula: see text]The rate constant of reaction (1) was independent of the solvent, whereas k2 was dependent on the solvent. The ratio k2/k1 was about 10.

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.

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 nitrous oxide I. Secondary catalytic and surface effects

1955 ◽  
Vol 231 (1185) ◽  
pp. 162-178 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Nitrous Oxide ◽  
Surface Reaction ◽  
Order Rate Constant ◽  
Side Reactions ◽  
Chain Reactions ◽  
First Order ◽  
Reaction Vessels ◽  
Decomposition Of Nitrous Oxide

In the region of pressure 0 to 500 mrn approximately to the equation the thermal decomposition of nitrous oxide conforms approximately to the equation k = an /1 + a'n + bn , where k is the form al first-order rate constant, — (1/n) d n /d t , n the initial concentration and a, a' and b are nearly constant. Above about 100 m m this expression approximates to k = A + bn , which holds up to several atmospheres. Fresh and more detailed experiments have once again disproved the suggestion that the first term in these expressions is due to a surface reaction. (In certain states of reaction vessels, made of a particular brand of silica, a surface reaction may appear but is immediately recognizable by special criteria, and can be eliminated.) Detailed study of the formation of nitric oxide in the course of the decomposition, and of the effect of inert gas upon this process, shows that side reactions involving oxygen atoms, chain reactions and catalysis by nitric oxide play only minor parts in determining the shape of the k-n curve. The form of this curve, which is an inherent character of the reaction N 2 O = N 2 + O, raises theoretical questions of considerable interest.

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