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 thermal decomposition of diethyl ether. V. The production of ethanol from diethyl ether and the pyrolysis of ethanol

1958 ◽  
Vol 245 (1240) ◽  
pp. 75-83 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Diethyl Ether ◽  
Type Reaction ◽  
First Order

The two modes of decomposition of ethanol at 525 °C, namely dehydration and dehydrogenation, are affected by nitric oxide in a manner similar to the analogous modes of decomposition of diethyl ether. Although the dehydration of ethanol is inhibitable to 30% (analogous ether mode nearly uninhibitable), the dehydrogenation is inhibitable to 2% (analogous ether mode inhibitable to about 25%). The overall reaction is approximately of the first order with respect to the initial ethanol pressure. Large amounts of nitric oxide accelerate the decomposition of ethanol, and a dehydrogenation type reaction is induced to a much greater extent than a dehydration type reaction (as for the analogous modes of ether decomposition). The mechanism is discussed.

The thermal decomposition of diethyl ether. III. The action of inhibitors and the mechanism of the reaction

1958 ◽  
Vol 245 (1240) ◽  
pp. 49-67 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Diethyl Ether ◽  
Rate Constant ◽  
Initial Pressure ◽  
Direct Analysis ◽  
Reaction Products ◽  
First Order ◽  
Molecular Decomposition ◽  
Induced Reaction

Small quantities of nitric oxide reduce the rate of thermal decomposition of diethyl ether at 525 °C to about one-quarter. Much larger amounts accelerate the decomposition, but the concentration ranges in which the ‘ maximally inhibited ’ reaction and the ‘ nitric-oxide-induced’ reaction can be studied are so widely separated that these reactions can be treated as two distinct entities. The ‘uninhibited’ reaction constitutes a third. Reaction products and kinetics are recorded for all three, and nitric oxide consumption is measured for the first two. In all three the major products are the same, with secondary differences which are discussed. In the presence of nitric oxide small amounts of cyanides and other compounds are formed. In the nitric-oxide-induced reaction 1.4 molecules of ether are decomposed for each molecule of nitric oxide used up: in the maximally inhibited reaction the ratio, which is dependent on the ether pressure, is very much greater. The rate of the maximally inhibited reaction is independent of the concentration of nitric oxide, or of propylene, and the same for the two inhibitors (as is now proved by direct analysis). The first-order rate constant varies with the initial pressure of ether according to the equation k inhib. = ( A [ether])/(1 + B [ether]) + C [ether]. The rate constant of the uninhibited reaction varies with ether pressure according to an expression which, although probably of different algebraical form, is empirically similar to the above over a considerable range. The nitric-oxide-induced reaction is nearly of the first order with respect both to ether pressure and to nitric oxide pressure. The maximally inhibited reaction is shown to be most probably a molecular decomposition of the ether. The uninhibited reaction is predominantly a chain reaction, the mechanism of which is discussed. The nitric-oxide-induced reaction, it is suggested on the basis of the experimental evidence, is largely initiated by a generation of radicals in an attack of nitric oxide on ether. It is possibly also in part a molecular decomposition of ether caused by collision with nitric oxide.

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 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.

The kinetics of hydration of tricalcium silicate

1970 ◽  
Vol 48 (21) ◽  
pp. 3291-3299 ◽  
Author(s):  
K. G. McCurdy ◽  
B. P. Erno
Keyword(s):  
Reaction Mechanism ◽  
Intermediate Product ◽  
Activation Energies ◽  
Tricalcium Silicate ◽  
Rate Data ◽  
Large Excess ◽  
First Order ◽  
Kinetics Of ◽  
Subsequent Decomposition

An investigation has been made of the kinetics of hydration of tricalcium silicate at several temperatures in a large excess of water in the presence of various added ions. The rate data have been interpreted by a reaction mechanism which involves: (a) the first order hydration of tricalcium silicate to form an intermediate product, 1.5CaO•SiO2, which can react by two pathways, (b) the direct first order decomposition of intermediate, 1.5CaO•SiO2, to form lime and silica or (b′) complexing of intermediate with silica and subsequent decomposition to form lime and silica. This reaction mechanism predicts the rate of production of base during the hydration. The effect of various added ions is interpreted in terms of the proposed mechanism.Rate constants and activation energies for the various steps in the proposed mechanism are reported.

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.

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 CUPRENE GROWTH

1950 ◽  
Vol 28b (7) ◽  
pp. 358-372
Author(s):  
Cyrias Ouellet ◽  
Adrien E. Léger
Keyword(s):  
Nitric Oxide ◽  
Activation Energy ◽  
Carbon Monoxide ◽  
Apparent Activation Energy ◽  
Copper Catalyst ◽  
Maximum Velocity ◽  
Static System ◽  
Reaction Velocity ◽  
First Order ◽  
Kinetics Of

The kinetics of the polymerization of acetylene to cuprene on a copper catalyst between 200° and 300 °C. have been studied manometrically in a static system. The maximum velocity of the autocatalytic reaction shows a first-order dependence upon acetylene pressure. The reaction is retarded in the presence of small amounts of oxygen but accelerated by preoxidation of the catalyst. The apparent activation energy, of about 10 kcal. per mole for cuprene growth between 210° and 280 °C., changes to about 40 kcal. per mole above 280 °C. at which temperature a second reaction seems to set in. Hydrogen, carbon monoxide, or nitric oxide has no effect on the reaction velocity. Series of five successive seedings have been obtained with cuprene originally grown on cuprite, and show an effect of aging of the cuprene.

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.

Studies on Metal Hydroxy Compounds. XIII. Thermal Analyses and Decomposition Kinetics of Hydroxystannates of Bivalent Metals

1971 ◽  
Vol 49 (17) ◽  
pp. 2813-2816 ◽  
Author(s):  
P. Ramamurthy ◽  
E. A. Secco
Keyword(s):  
Thermal Analyses ◽  
Decomposition Reaction ◽  
Decomposition Kinetics ◽  
Order Reaction ◽  
First Order ◽  
Calorimetric Measurements ◽  
Bivalent Metals ◽  
Hydroxy Compounds ◽  
Kinetics Of ◽  
Subsequent Decomposition

The thermal analyses of hexahydroxystannates of bivalent metals of the type Me[Sn(OH)6], where Me = Zn, Co, Cu, Ni, Mn, Ca, Mg, Cd, Sr, reveal that the primary mode of decomposition occurs by dehydroxylation and subsequent decomposition of the metastannate residue occurs in the Zn, Cu, Mn, Ca, and Mg compounds. Calorimetric measurements along with related enthalpic values for the decomposition reaction are given. The kinetics of thermal decomposition of all compounds studied, except the Cd and Mg analogues, follow first order reaction kinetics up to α ~ 0.9.

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