The thermal and photochemical decomposition of cis-1,2-cyclobutanedicarboxylic anhydride in the vapour phase

1982 ◽  
Vol 60 (21) ◽  
pp. 2692-2696
Author(s):  
R. A. Back ◽  
J. M. Parsons
Keyword(s):  
Thermal Decomposition ◽  
Vapour Phase ◽  
Major Product ◽  
Thermal Reaction ◽  
Static System ◽  
Unimolecular Decomposition ◽  
First Order ◽  
Major Process ◽  
Photochemical Decomposition ◽  
Ultraviolet Photolysis

The thermal decomposition of cis-1,2-cyclobutanedicarboxylic anhydride (CBA) has been studied in a static system in the range 625–725 K. The major process observed was a homogeneous unimolecular decomposition to form ethylene and maleic anhydride, with first-order rate parameters A = 1.14(± 0.1) × 1014s−1 and E = 55.1 ± 1 kcal/mol. A very minor decomposition channel yielding butadiene, CO2, and CO was also observed, with A = 8.4 (± 0.1) ×1014 s−1 and E = 67.5 ± 1 kcal/mol.The decomposition induced by a pulsed CO2 laser was also studied briefly; the same two decomposition channels were observed and their dependence on fluence and pressure examined.The ultraviolet photolysis of CBA was also investigated between 210 and 365 nm. In addition to the products found in the thermal reaction, cyclobutene was also a major product, and product ratios were measured as a function of wavelength and added CO2. Mechanisms in the three systems are discussed and compared.

The Thermal Decomposition of Boron Trimethyl

1962 ◽  
Vol 15 (4) ◽  
pp. 744 ◽  
Author(s):  
AS Buchanan ◽  
F Creutzberg
Keyword(s):  
Thermal Decomposition ◽  
Activation Energies ◽  
Major Product ◽  
Main Reaction ◽  
Static System ◽  
Hydrogen Formation ◽  
First Order ◽  
Rate Expression

The thermal decomposition of boron trimethyl has been studied in a static system in the range 468-513 �C and was found to be first order with a rate expression������������� k1=1.2 x 1012e-[56 000/RT] sec-1. The activation energies for methane and hydrogen formation were found to be 76 and 75 kcal, respectively. The stoicheiometry for the main reaction was found to be ���������������� 2B(CH3)3 → 2CH4 + H2 + [B(CH2)2]2. Preliminary experiments on the photolysis of boron trimethyl indicated that methane was the major product.

The gas-phase photochemistry and thermal decomposition of glyoxylic acid

1985 ◽  
Vol 63 (2) ◽  
pp. 542-548 ◽  
Author(s):  
R. A. Back ◽  
S. Yamamoto
Keyword(s):  
Thermal Decomposition ◽  
Carbon Monoxide ◽  
Absorption Spectrum ◽  
Gas Phase ◽  
Singlet State ◽  
Glyoxylic Acid ◽  
Static System ◽  
First Order ◽  
Increasing Temperature ◽  
Homogeneous Formation

The photolysis of glyoxylic acid vapour has been studied at five wavelengths, 382, 366, 346, 275, and 239 nm, and pressures from about 1 to 6 Torr, at a temperature of 355 K. Major products were CO2 and CH2O, initially formed in almost equal amounts, while minor products were CO and H2. Except at 382 nm, the system was complicated by the rapid secondary photolysis of CH2O. Three primary processes are suggested, each involving internal H-atom transfer followed by dissociation.The absorption spectrum is reported and shows the three distinct absorption systems. A finely-structured spectrum from about 320 to 400 nm is attributed to a transition to the first excited π* ← n+ singlet state; a more diffuse absorption ranging from about 290 nm to a maximum at 239 nm is assigned to the π* ← n− state, while a much stronger absorption beginning below 230 nm is attributed to the π* ← π transition. Product ratios vary with wavelength and depend on which excited state is involved.The thermal decomposition was studied briefly in a static system at temperatures from 470 to 710 K and pressures from 0.4 to 8 Torr. Major products were again CO2 and CH2O, but the latter was always less than stoichiometric. First-order rate constants for the apparently homogeneous formation of CO2 are described by Arrhenius parameters log A (s−1) = 7.80 and E = 30.8 kcal/mol. Carbon monoxide and H2 were minor products, and the CO/CO2 ratio increased with increasing temperature and showed some surface enhancement at lower temperatures. The SF6-sensitized thermal decomposition of glyoxylic acid, induced by a pulsed CO2 laser, was briefly studied, with temperatures estimated to be in the 1100–1600 K range, and the CO/CO2 ratio increased with increasing temperature, continuing the trend observed in the static system.

THE THERMAL DECOMPOSITION OF STYRENE–BUTADIENE POPCORN POLYMER

1950 ◽  
Vol 28b (1) ◽  
pp. 5-16
Author(s):  
C. A. Winkler ◽  
J. Halpern
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Linear Relation ◽  
Frequency Factor ◽  
Thermal Reaction ◽  
Cross Linking ◽  
First Order ◽  
Bond Scission ◽  
Styrene Butadiene ◽  
Kinetics Of

At temperatures of the order of 250 °C., popcorn polymer undergoes decomposition to soluble polymer. The reaction is catalyzed by peroxides present in the popcorn when the latter is formed. These peroxides may be removed by extracting the polymer with benzene. The kinetics of both the catalyzed and purely thermal solubilization reactions were investigated. The rates of both reactions are first order, the catalyzed degradation having a higher activation energy and a higher frequency factor. The rate of the thermal reaction decreases and its activation energy increases with increasing butadiene content of the polymer. A linear relation between the activation energy and the log of the frequency factor, for the decomposition of popcorn polymers of different butadiene contents, was observed. The results indicate that the rate of solubilization is determined by the activation energy of the bond scission process, and is independent of the degree of cross-linking of the polymer.

The Thermal Decomposition of N-Benzoyl-N′-1-cyanocyclohexyl Diimide

1972 ◽  
Vol 50 (13) ◽  
pp. 2143-2146 ◽  
Author(s):  
Thomas R. Lynch ◽  
Frederick N. MacLachlan
Keyword(s):  
Thermal Decomposition ◽  
Major Product ◽  
First Order

N-Benzoyl-N′-1-cyanocyclohexyl diimide decomposes in toluene in a first-order manner between 81 and 102°, k = 1015.08e−32.54 ± 1.35/RT. The major product is N-benzoyl-N-cyclohexane carbonyl imide.

KINETICS OF THE THERMAL DECOMPOSITION OF TETRAMETHYLTETRAZEN

1960 ◽  
Vol 38 (2) ◽  
pp. 298-299 ◽  
Author(s):  
J. S. Watson ◽  
A. J. Waring
Keyword(s):  
Thermal Decomposition ◽  
Static System ◽  
Arrhenius Parameters ◽  
First Order ◽  
Kinetics Of

The kinetics of the thermal decomposition of tetramethyltetrazen (T.M.T.) have been studied in a static system at pressures up to 1.8 × 10−2 mm and temperatures between 125.5 and 147.5 °C by measuring the rate of production of nitrogen. The results show that the decomposition is first order in T.M.T. at the pressures used and give approximate values for the Arrhenius parameters.

Kinetics and mechanism of the thermal decomposition of the thiosulphatopentaamminecobalt(III) ion in dilute aqueous acid

1986 ◽  
Vol 64 (2) ◽  
pp. 311-313
Author(s):  
Anthony Martin Newton
Keyword(s):  
Thermal Decomposition ◽  
Acetic Acid ◽  
Sodium Acetate ◽  
Major Product ◽  
Order Kinetic ◽  
Sodium Acetate Buffer ◽  
Reaction Products ◽  
First Order ◽  
Aqueous Acid ◽  
Reactive Complex

In acetic acid – sodium acetate buffer of pH 5.6 (25 °C) the Co(NH3)5S2O3+ ion undergoes redox decomposition rather than aquation. First-order kinetic are observed and the reaction products Co2+, NH3, and S4O62− are due to internal reduction of Co(III) by coordinated S2O32−. In dilute perchloric acid of pH < 4 the rate is retarded, first-order plots are not linear, and S4O62− is not a major product of the reaction. It is proposed that, in dilute HClO4, protonation of Co(NH3)5S2O3+ depletes the concentration of the reactive complex and that decomposition of coordinated HS2O3− occurs. Conversion of O-bonded S2O32− to S-bonded S2O32− in the reactive complex is also considered.

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2019 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
Joseph Remias ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

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 THERMAL DECOMPOSITION OF HEXAFLUOROAZOMETHANE

1962 ◽  
Vol 40 (5) ◽  
pp. 930-934 ◽  
Author(s):  
Elizabeth Leventhal ◽  
Charles R. Simonds ◽  
Colin Steel
Keyword(s):  
Thermal Decomposition ◽  
High Pressure ◽  
Rate Constant ◽  
Static System ◽  
Homogeneous Reaction

The pyrolysis of hexafluoroazomethane has been studied in a static system between 0.3 mm and 73 mm and 572 °K and 634 °K by measuring the rate of nitrogen formation. The rate constant of the high-pressure homogeneous reaction is given by k = 1016.17±0.15 exp (−55,200 ± 400/RT) sec−1

Radicals derived from heteroaromatic systems. II. Thiazolyl radicals

1970 ◽  
Vol 48 (22) ◽  
pp. 3554-3562 ◽  
Author(s):  
Mrs. A. L. Lee ◽  
Donald Mackay ◽  
E. L. Manery
Keyword(s):  
Thermal Decomposition ◽  
Silver Oxide ◽  
Major Product ◽  
Phenyl Ester

2-Thiazolylhydrazine and all three thiazole carbonyl peroxides have been synthesized and examined as radical precursors in solution in benzene, bromobenzene, and cumene. Silver oxide oxidation of the hydrazine or thermal decomposition of the 2-peroxide gives good yields of 2-arylthiazoles but negligible amounts of esters; in cumene a trace of bicumyl is formed. The isomer ratios in bromobenzene and cumene fully support the involvement of 2-thiazolyl radicals (1).The 4-carbonyl peroxide gives fair yields of 4-arylthiazoles but the phenyl ester is also a major product in benzene, indicative of reactions of both 4-thiazolyl radicals (2) and thiazole-4-carbonyloxy radicals. The 5-peroxide gives no products clearly diagnostic of 5-thiazolyl radicals (3) or thiazole-5-carbonyloxy radicals. Bicumyl is a major product of the reactions of the 4- and the 5-peroxides in cumene.

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