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.

Observation of a radical intermediate in the one electron oxidation of 5-methyl-1-thia-5-azacyclooctane by •Br2−

1984 ◽  
Vol 62 (9) ◽  
pp. 1874-1876 ◽  
Author(s):  
Warren Kenneth Musker ◽  
Parminder S. Surdhar ◽  
Rizwan Ahmad ◽  
David A. Armstrong
Keyword(s):  
Aqueous Solution ◽  
Rate Constant ◽  
Half Life ◽  
Cation Radical ◽  
Order Rate Constant ◽  
Type Structure ◽  
Radical Intermediate ◽  
Text Type ◽  
First Order ◽  
The One

The one electron oxidant •Br2− reacts with 5-methyl-1-thia-5-azacyclooctane (4) in aqueous solution at high pH with an overall rate constant of ~2 × 108 M s−1. The radical intermediate produced has a broad maximum at 500 nm with ε = 2400 M−1 cm−1 and at pH 10 decays with a first order rate constant of 2.3 ± 0.3 × 104 s−1, first half-life of 30 ± 5 μs. Its characteristics do not correspond to those of the [Formula: see text] species reported by Asmus and co-workers. The species appears to be the same as the cation radical reported earlier in the one electron oxidation of 4 in acetonitrile. This species is considered to have an [Formula: see text] type structure, which provides transannular stabilization.

ChemInform Abstract: GAS PHASE THERMAL DECOMPOSITION OF TERT.-BUTYL ALCOHOL

1974 ◽  
Vol 5 (38) ◽  
pp. no-no
Author(s):  
DAVID LEWIS ◽  
MARK KEIL ◽  
MICHAEL SARR
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Butyl Alcohol ◽  
Tert Butyl ◽  
Tert Butyl Alcohol

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.

Kinetics and mechanism of hydrolysis of substituted phenyl N-(4-methylphenyl)sulphonylcarbamates. Solvolysis of 3-nitrophenyl N-(4-methylphenyl)-sulphonylcarbamate in mixtures water-1,4-dioxane and water-tert-butyl alcohol and its decomposition to neutral molecules in non-aqueous media

1979 ◽  
Vol 44 (9) ◽  
pp. 2639-2652 ◽  
Author(s):  
Jitka Moravcová ◽  
Miroslav Večeřa
Keyword(s):  
Organic Solvents ◽  
Ph Dependence ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Base Catalysis ◽  
Hydrolysis Rate ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Hydrolysis Of

pH Dependence of hydrolysis rate of the substituted phenyl N-(4-methylphenyl)sulphonylcarbamates has been followed in aqueous medium. The activation parameters and the Hammet reaction constant (ρ = 2.4) have been determined at pH 11.3. For hydrolysis of 3-nitrophenyl N-(4-methylphenyl)sulphonylcarbamate (pK about 3.5) no general base catalysis has been found. The hydrolysis mechanism is discussed. Perturbation of the water structure by organic solvents (1,4-dioxane and tert-butyl alcohol) has been used for differentiation of ElcB and Bac2 mechanisms, 2,4-dinitrophenyl acetate being used for comparison. The decomposition rates of 3-nitrophenyl N(4-methylphenyl)sulphonylcarbamate have been determined in six organic solvents. Mechanism of spontaneous splitting of the carbamate molecule in non-aqueous media is discussed.

Secondary α-deuterium kinetic isotope effects for the E2 reaction of the 2-phenylethyl halides with tert-butoxide ion in tert-butyl alcohol

1985 ◽  
Vol 63 (1) ◽  
pp. 100-102 ◽  
Author(s):  
Peter James Smith ◽  
Kanchugarakoppal S. Rangappa ◽  
Kenneth Charles Westaway
Keyword(s):  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Order Rate Constant ◽  
Butyl Alcohol ◽  
Tert Butyl ◽  
Kinetic Isotope ◽  
Tert Butyl Alcohol ◽  
Elimination Reactions ◽  
Leaving Groups ◽  
High Base

Secondary α-deuterium kinetic isotope effects have been determined for the elimination reactions of 2-phenylethyl halides with tert-butoxide in tert-butyl alcohol at 40 °C in the presence and absence of the crown ether 18C6. The second-order rate constant k2 and the normal (kH/kD)α effect remained constant when the tert-butoxide concentration was varied for reaction of the iodo and bromo compounds. However, both the magnitude of k2 and the secondary α-deuterium isotope effect were significantly dependent on [t-BuO−] when chlorine and fluorine are the leaving groups. It is noteworthy that (kH/kD)α is inverse for the reaction of both the chloro and fluoro compounds at "low" base concentrations and normal at "high" base concentrations. These results are discussed in terms of both syn- and anti-elimination pathways promoted by various associated and dissociated base species. It is suggested that the (kH/kD)α effect may be useful as a criterion for determining the stereochemistry of E2 elimination reactions.

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.

Isolation of the initial step in the thermal decomposition of di-tert-butyl peroxide

1969 ◽  
Vol 47 (24) ◽  
pp. 4808-4809 ◽  
Author(s):  
C. K. Yip ◽  
H. O. Pritchard
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Initial Step ◽  
Butyl Alcohol ◽  
Major Product ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Peroxide Decomposition ◽  
Butyl Peroxide

The thermal decomposition of di-tert-butyl peroxide in the presence of propane has been studied at total pressures up to 100 atm. At the highest propane concentrations, the major product of the decomposition is tert-butyl alcohol, and extrapolation to infinite propane pressure indicates that the initial step in the peroxide decomposition is exclusively the formation of two tert-butoxy radicals. The activation energy for the abstraction of hydrogen from propane by t-BuO radicals is discussed.

Thermal decomposition of di-tert-butyl peroxide at high pressure

1968 ◽  
Vol 46 (16) ◽  
pp. 2721-2724 ◽  
Author(s):  
D. H. Shaw ◽  
H. O. Pritchard
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
High Pressure ◽  
Shock Tube ◽  
Total Pressure ◽  
Order Rate Constant ◽  
Kcal Mole ◽  
First Order ◽  
Tert Butyl ◽  
Butyl Peroxide

The thermal decomposition of di-tert-butyl peroxide has been studied in the presence of carbon dioxide at total pressures from 0.05 to 15 atm and temperatures from 90–130 °C. The first-order rate constant for the decomposition is independent of total pressure in this range, with Arrhenius parameters E = 37.8 ± 0.3 kcal/mole and log A(s−1) = 15.8+0.2. A reevaluation of previous data on this reaction leads us to recommend E = 37.78 ± 0.06 kcal/mole and log A(s−1) = 15.80 ± 0.03 over the temperature range 90–350 °C; extension of this range to higher temperatures using a shock tube would be worthwhile.

scholarly journals Mechanism of protection of adenosine from tert-butoxyl radicals and repair of adenosine radicals by α-tocopherol in aqueous solution

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
G. Vijayalakshmmi ◽  
M. Adinarayanna ◽  
P. Jayaprrakash Rao
Keyword(s):  
Aqueous Solution ◽  
Rate Constant ◽  
Butyl Alcohol ◽  
Quantum Yields ◽  
Oh Radicals ◽  
Butyl Hydroperoxide ◽  
Tert Butyl ◽  
Tert Butyl Hydroperoxide ◽  
Tert Butyl Alcohol

The rates of oxidation of adenosine and α-tocopherol by tert-butoxyl radicals (t-BuO•) were studied spectrophotometrically. Radicals (t-BuO•) were generated by the photolysis of tert-butyl hydroperoxide (t-BuOOH) in presence of tert-butyl alcohol to scavenge •OH radicals. The rates and the quantum yields () of oxidation of α-tocopherol by t-BuO• radicals were determined in the absence and presence of varying concentrations of adenosine. An increase in the concentration of adenosine was found to decrease the rate of oxidation of α-tocopherol, suggesting that adenosine and α-tocopherol competed for t-BuO• radicals. From competition kinetics, the rate constant of α-tocopherol reaction with t-BuO• was calculated to be 7.29 x 108 dm3 mol-1 s-1. The quantum yields expt and cal values suggested that α-tocopherol not only protected adenosine from t-BuO• radicals, but also repaired adenosine radicals, formed by the reaction of adenosine with t-BuO• radicals.

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