The thermal decomposition of cyclobutane-1,2-dione

1985 ◽  
Vol 63 (11) ◽  
pp. 2945-2948 ◽  
Author(s):  
J.-R. Cao ◽  
R. A. Back
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Vapor Pressure ◽  
Gas Phase ◽  
Rate Constant ◽  
Surface Reaction ◽  
Order Rate Constant ◽  
Reaction Vessel ◽  
Arrhenius Parameters ◽  
First Order

The thermal decomposition of cyclobutane-1,2-dione has been studied in the gas phase at temperatures from 120 to 250 °C and pressures from 0.2 to 1.5 Torr. Products were C2H4 + 2CO, apparently formed in a simple unimolecular process. The first-order rate constant was strongly pressure dependent, and values of k∞ were obtained by extrapolation of plots of 1/k vs. 1/p to1/p = 0. Experiments in a packed reaction vessel showed that the reaction was enhanced by surface at the lower temperatures. Arrhenius parameters for k∞, corrected for surface reaction, were log A (s−1) = 15.07(±0.3) and E = 39.3(±2) kcal/mol. This activation energy seems too low for a biradical mechanism, and it is suggested that the decomposition is probably a concerted process. The vapor pressure of solid cyclobutane-1,2-dione was measured at temperatures from 22 to 62 °C and a heat of sublimation of 13.1 kcal/mol was estimated.

Thermal decomposition of citraconic anhydride

1971 ◽  
Vol 24 (4) ◽  
pp. 771 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constant ◽  
Arrhenius Equation ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
First Order ◽  
First Order Kinetics ◽  
Citraconic Anhydride

Citraconic anhydride decomposes in the gas phase over the range 440- 490� to give carbon dioxide, carbon monoxide, and propyne which undergoes some polymerization to trimethylbenzenes. The decomposition obeys first-order kinetics, and the Arrhenius equation ������������������� k1 = 1015.64 exp(-64233�500/RT) (s-1) describes the variation of rate constant with temperature. The rate constant is unaffected by the addition of isobutene or by increase in the surface/volume ratio of the reaction vessel. The reaction appears to be unimolecular and if a diradical intermediate is involved it may not be fully formed in the transition state.

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.

THE DECOMPOSITION OF SILYL PEROXIDES

1964 ◽  
Vol 42 (5) ◽  
pp. 985-989 ◽  
Author(s):  
Richard R. Hiatt
Keyword(s):  
Thermal Decomposition ◽  
Rate Constant ◽  
Half Life ◽  
Order Rate Constant ◽  
Butyl Alcohol ◽  
Base Catalysis ◽  
First Order ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Acid And Base

The thermal decomposition of tert-butyl trimethylsilyl peroxide has been investigated and found to be sensitive to acid and base catalysis and to the nature of the solvent. In heptane and iso-octane the first-order rate constant could be expressed as 1.09 × 1015e−41200/RT and in 1-octene as 3.90 × 1015e−41200/RT (sec−1). The half life at 203 °C was about 1 hour. The reaction was faster in aromatic solvents; in chlorobenzene it was complicated by formation of HCl from the solvent.Products of the reaction were acetone, tert-butyl alcohol and hexamethyldisiloxane.

Reactions with half-lives of several years

1964 ◽  
Vol 17 (4) ◽  
pp. 406 ◽  
Author(s):  
GA Bottomley ◽  
GL Nyberg
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Virial Coefficient ◽  
Energy Equation ◽  
Second Virial Coefficient ◽  
First Order ◽  
First Order Kinetics ◽  
Reciprocal Temperature ◽  
Temperature Activation

The gas-phase thermal decomposition of dimethyldiazirine, (CH3)2CN2, at very slow rates has been investigated using precision gas-volumetric techniques previously applied to second virial coefficient studies. At 50-70� the first-order kinetics correspond to half-lives about 0.3-3.0 years. The present results, together with data obtained by other workers using conventional apparatus at 124-174�, fit a single log rate-reciprocal temperature activation energy equation.

THE THERMAL DECOMPOSITION OF METHYL HYDROPEROXIDE

1965 ◽  
Vol 43 (8) ◽  
pp. 2236-2242 ◽  
Author(s):  
Alexander D. Kirk
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constants ◽  
Dimethyl Phthalate ◽  
Kcal Mole ◽  
First Order ◽  
Methyl Hydroperoxide ◽  
Expected Values ◽  
Homogeneous Decomposition

The thermal decomposition of methyl hydroperoxide has been studied in solution and in the gas phase. The decomposition was found to be partly heterogeneous in solution in dimethyl phthalate and no reliable rate constants were obtained. Use of the toluene carrier method for the gas phase work enabled measurement of the rate constant for the homogeneous decomposition. The first order rate constants obtained range from 0.19 s−1 at 292 °C to 1.5 s−1 at 378 °C, leading to log A, 11± 2, and activation energy, 32 ± 5 kcal/mole. These results are compared with the expected values of log A, 13–14, and activation energy, 42 kcal/mole. The significance of these findings is discussed.

Thermal decomposition of methyl azide

1970 ◽  
Vol 48 (7) ◽  
pp. 1140-1147 ◽  
Author(s):  
M. S. O'Dell Jr. ◽  
B. deB. Darwent
Keyword(s):  
Thermal Decomposition ◽  
Rate Constant ◽  
Order Rate Constant ◽  
First Order ◽  
Hexamethylene Tetramine ◽  
Order Rate

The thermal decomposition of gaseous methyl azide has been investigated at conversions of less than 1% at 155, 170, and 200 °C. The reaction has been shown to be homogeneous and unimolecular, the first-order rate constant being kun1 = 2.85 × 1014 exp − (40 500/RT). The decomposition results in the formation of CH3N(X3∑−) and N2(X1∑g+). The CH3N(X3∑−) do not react with CH3N3 to produce N2, but do form a polymer of composition similar to hexamethylene tetramine and also react with olefins. The major products are N2 and polymer; small amounts of H2 and CH4, but no C2H6, are formed.

The thermal isomerization of 1.2-dimethyl cyclo propane I. Cis-trans isomerization

1960 ◽  
Vol 257 (1288) ◽  
pp. 122-131 ◽  
Keyword(s):  
Gas Chromatography ◽  
High Pressure ◽  
Order Rate Constant ◽  
Enthalpy Change ◽  
Reaction Vessel ◽  
Unimolecular Reaction ◽  
Arrhenius Parameters ◽  
Geometrical Isomerization ◽  
First Order ◽  
Structural Isomerization

This isomerization has been investigated between 380 and 453 °C. In this temperature range, in an ' aged ’ reaction vessel, cis-trans isomerization occurs as a reversible homogeneous unimolecular reaction. The rates of this geometrical isomerization have been measured and the Arrhenius parameters evaluated. In the case of cis 1. 2 -dimethyl cyclo propane, the rate equation obtained is k ∞ = 10 15.25 exp ( - 59 420 ± 500/ RT ) sec -1 . The values of the equili­brium constant for the reaction have also been determined at various temperatures between 380 and 476 °C, and the value of the enthalpy change calculated. The first-order rate constant begins to decrease at about 16 mm, and has fallen to approximately 70 % of the high-pressure value at 0.1 mm. Occurring simultaneously with the geometrical isomerization is a structural isomerization to yield cis and trans pent-2-ene, 2-methylbut-l-ene and 2-methylbut-2-ene. The geometrical isomerization is considerably faster than the structural isomerization. Approximate values for the Arrhenius parameters relating to the various products of the structural isomerization have been determined. Gas chromatography, by means of a katharometer detector with electronic integration, has been used throughout and has been developed to give a precision of ± 0.5 % in the analysis of the reaction mixtures.

THE THERMAL DECOMPOSITION OF PHENYLACETIC ACID

1960 ◽  
Vol 38 (8) ◽  
pp. 1261-1270 ◽  
Author(s):  
Margaret H. Back ◽  
A. H. Sehon
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Carbon Monoxide ◽  
Rate Constant ◽  
Phenylacetic Acid ◽  
Order Process ◽  
First Order ◽  
Kinetics Of ◽  
Dissociation Step

The thermal decomposition of phenylacetic acid was investigated by the toluene-carrier technique over the temperature range 587 to 722 °C. The products of the pyrolysis were carbon dioxide, carbon monoxide, hydrogen, methane, dibenzyl, and phenylketene. From the kinetics of the decomposition it was concluded that the reaction[Formula: see text]was a homogeneous, first-order process and that the rate constant of this dissociation step was represented by the expression k = 8 × 1012.e−55,000/RT sec−1. The activation energy of this reaction may be identified with D(C6H5CH2—COOH). The possible reactions of carboxyl radicals are discussed.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: XII. THE DECOMPOSITION OF GLYOXAL TETRA-ACETATE

1940 ◽  
Vol 18b (12) ◽  
pp. 410-413 ◽  
Author(s):  
J. C. Arnell ◽  
J. R. Dacey ◽  
C. C. Coffin
Keyword(s):  
Activation Energy ◽  
Acetic Anhydride ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Independent Factor ◽  
First Order ◽  
Order Rate ◽  
Gas Reactions

The decomposition of gaseous glyoxal tetra-acetate to acetic anhydride and glyoxal is homogeneous and unimolecular. Both the activation energy and the temperature independent factor of the first order rate constant are substantially larger than in the case of the diacetate esters. The decomposition velocity is given by the equation k = 1.8 × 1012e−39200/RT.

The thermal decompositions of carbamates. II. Methyl N-methylcarbamate

1972 ◽  
Vol 25 (7) ◽  
pp. 1453 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Gas Phase ◽  
Rate Constants ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
Phase Reaction ◽  
Methyl Isocyanate ◽  
Gas Phase Reaction ◽  
First Order

Methyl N-methyloarbamate decomposes in the range 370-422� to give methyl isocyanate and methanol. The reaction is first order in carbamate, and the variation of the rate constants with temperature is given by the equation. k = 1012.39 exp(-4806O/RT) (s-l; activation energy in cal mol-l) Rate constants are unaffected by the addition of isobutene or by increase in the surface to volume ratio of the reaction vessel. The addition of alcohols or amines does not reverse the process. The decomposition is considered to be a homogeneous, unimolecular gas-phase reaction, probably proceeding through a four-centred transition state.

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