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 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 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 REACTION OF 2,2-DIPHENYL-1-PICRYLHYDRAZYL WITH SECONDARY AMINES

1958 ◽  
Vol 36 (12) ◽  
pp. 1729-1734 ◽  
Author(s):  
J. E. Hazell ◽  
K. E. Russell
Keyword(s):  
Secondary Amine ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Major Product ◽  
The Other ◽  
Secondary Amines ◽  
First Order ◽  
Kinetics Of

The reaction of DPPH (2,2-diphenyl-1-picrylhydrazyl) with N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, diphenylamine, and methylaniline has been studied and has been shown to be primarily a hydrogen abstraction process. Two moles DPPH react with 1–1.15 moles secondary amine to give 1.7–1.8 moles 2,2-diphenyl-1-picrylhydrazine and further products.The reaction between DPPH and N-phenyl-1-naphthylamine is first order with respect to each reactant. The reaction of DPPH with the other amines is retarded by the major product 2,2-diphenyl-1-picrylhydrazine and the kinetics of the over-all reaction are complex. However second-order rate constants and activation energies have been obtained using initial rates of reaction. Possible reaction mechanisms are discussed.

scholarly journals Allyl radicals from 3,3′-azo-1-propene

1970 ◽  
Vol 48 (17) ◽  
pp. 2745-2754 ◽  
Author(s):  
Basil H. Al-Sader ◽  
Robert J. Crawford
Keyword(s):  
Activation Energies ◽  
Major Product ◽  
Bond Dissociation Energies ◽  
Kcal Mole ◽  
Allyl Radical ◽  
First Order ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
First Order Kinetics

3,3′-Azo-1-propene (4), 3,3′-azo-1-propene-3,3′-d2 (5) and 3,3′-azo-1-propene-3,3,3′3′-d4 (6) have been synthesized and characterized. Thermolysis of 4, at 40–300 Torr, and in the region 150–170°, followed first order kinetics (Ea = 36.1 ± 0.2 kcal mole−1, log A = 15.54 ± 0.10) the major product, >99.9%, being 1,5-hexadiene (9). The presence of less than 0.1% propene suggests that the allyl radical is unable to abstract hydrogen from 4 or 9. Statistical scrambling of deuterium, in the products of thermolysis of 5 and 6, was observed. These results are interpreted in terms of a mechanism wherein allyl radicals are generated. Comparison of the activation energies for azoalkanes and 4 with the bond dissociation energies of hydrocarbons suggest that a good Polanyi plot is possible.

Thermal decomposition of propylene oxide

1968 ◽  
Vol 46 (14) ◽  
pp. 2454-2456 ◽  
Author(s):  
T. J. Hardwick
Keyword(s):  
Thermal Decomposition ◽  
Free Radicals ◽  
Propylene Oxide ◽  
First Order ◽  
Temperature Range ◽  
Rate Expression ◽  
Order Rate ◽  
Common Precursor

In the temperature range 402–425 °C, propylene oxide in a toluene medium decomposes to form propionaldehyde (60–70%), acetone (14%), and free radicals (25%). The ratio of products is invarient with temperature, suggesting a common precursor to all three products. Propionaldehyde further decomposes into free radicals. The first order rate expression for propylene oxide disappearance is3.7 × 1012 e−51900/RT s−1.

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.

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.

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