REACTIONS OF ALKOXY RADICALS: V. PHOTOLYSIS OF DI-t-BUTYL PEROXIDE

1958 ◽  
Vol 36 (9) ◽  
pp. 1227-1232 ◽  
Author(s):  
Garnett McMillan ◽  
M. H. J. Wijnen
Keyword(s):  
Activation Energy ◽  
Carbon Monoxide ◽  
Energy Difference ◽  
Butyl Alcohol ◽  
Reaction Products ◽  
Butyl Ether ◽  
Alkoxy Radicals ◽  
Temperature Range ◽  
Butyl Peroxide ◽  
Butoxy Radical

The photolysis of di-t-butyl peroxide has been investigated over the temperature range 25 ° to 79 °C. As reaction products were observed: acetone, t-butyl alcohol, methyl t-butyl ether, i-butylene oxide, ethane, methane, and carbon monoxide. The following reactions, involving the t-butoxy radical, have been studied:[Formula: see text]An activation energy difference of E2 − E6 = 3 kcal has been obtained.

Methanation on exfoliated and supported MoS2

1989 ◽  
Vol 67 (5) ◽  
pp. 862-866 ◽  
Author(s):  
Guenter A. Scholz ◽  
S. Roy Morrison
Keyword(s):  
Activation Energy ◽  
Carbon Monoxide ◽  
Transition Metal Catalysts ◽  
Surface Species ◽  
Reaction Products ◽  
Third Order ◽  
Ammonium Heptamolybdate ◽  
First Order ◽  
Methanation Reaction ◽  
Improved Performance

The methanation reaction on MoS2 exfoliated to a thickness of a few layers or less and adsorbed onto alumina is found to be very small. However, by calcining and resulfiding the exfoliated MoS2 catalysts, greatly improved performance is achieved that is at least equal to the commercial catalysts based on ammonium heptamolybdate. The creation of molybdenum oxysulflde surface species therefore appears to be a necessary step toward producing significant methanation rates with exfoliated and supported MoS2. The methanation products are almost exclusively CO2 and CH4, their mole ratios near unity, with otherwise only very much smaller amounts of longer chain hydrocarbons. The activation energy for methanation is generally observed to be near 100 kJ/mol, with the overall reaction being first order in the carbon monoxide concentration and third order in the hydrogen concentration. In contrast to the transition-metal catalysts, no water could be detected in the reaction products of the molybdenum based catalyst. Keywords: methanation reaction on MoS2, exfoliated and supported MoS2 as catalyst.

Dimethyl sulfoxide as a solvent in the Williamson ether synthesis

1969 ◽  
Vol 47 (11) ◽  
pp. 2015-2019 ◽  
Author(s):  
Russel G. Smith ◽  
Alan Vanterpool ◽  
H. Jean Kulak
Keyword(s):  
Reaction Time ◽  
Dimethyl Sulfoxide ◽  
Butyl Alcohol ◽  
Major Product ◽  
Hydroxyl Groups ◽  
Reaction Products ◽  
Butyl Chloride ◽  
Butyl Ether ◽  
Ether Synthesis ◽  
Williamson Ether Synthesis

Using the conventional Williamson ether synthesis, n-butyl ether was prepared from sodium hydroxide, n-butyl alcohol, and n-butyl chloride using excess of the alcohol as solvent in 61% yield after 14 h reaction time. However, when the excess alcohol was replaced by dimethyl sulfoxide, the yield of ether rose to 95% with 9.5 h reaction time. Other primary alkyl chlorides exhibited similar behavior to n-butyl chloride, but secondary alkyl chlorides and primary alkyl bromides gave little etherification, elimination being the major reaction. Unreactive halides, such as vinyl chloride, phenyl bromide, and 2,4-dinitrobromobenzene, were not etherified in dimethyl sulfoxide. The reaction products obtained from aliphatic dichlorides depended upon the relative positions of the chlorine atoms. Secondary alcohols reacted to give ethers, but tertiary alcohols were very unreactive. Polyols generally gave high yields of ethers, the major product being that in which all but one of the hydroxyl groups became etherified. Under forcing conditions, however, completely etherified polyols could be obtained.

Temperature dependence of photocatalytic CO2reduction by trans(Cl)–Ru(bpy)(CO)2Cl2: activation energy difference between CO and formate production

2017 ◽  
Vol 198 ◽  
pp. 263-277 ◽  
Author(s):  
Hitoshi Ishida ◽  
Akihiko Sakaba
Keyword(s):  
Activation Energy ◽  
Carbon Monoxide ◽  
Temperature Dependence ◽  
Catalytic System ◽  
Energy Difference ◽  
Catalytic Cycle ◽  
The Difference ◽  
A Minor ◽  
Increasing Temperature ◽  
Formate Production

The temperature dependence of photocatalytic CO2reduction bytrans(Cl)–Ru(bpy)(CO)2Cl2(bpy: 2,2′-bipyridine) has been researched in ethanol (EtOH)/N,N-dimethylacetamide (DMA) solutions containing [Ru(bpy)3]2+(a photosensitizer) and 1-benzyl-1,4-dihydronicotinamide (BNAH, an electron donor). The catalytic system efficiently reduces CO2to carbon monoxide (CO) with formate (HCOO−) as a minor product. The mechanism of the catalysis consists of the electron-relay cycle and the catalytic cycle: in the former cycle the photochemically generated reduced species of the photosensitizer injects an electron to the catalyst, and in the latter the catalyst reduces CO2. At a low concentration of the catalyst (5.0 μM), where the catalytic cycle is rate-determining, the temperature dependence of CO/HCOO−is also dependent on the EtOH contents: the selectivity of CO/HCOO−decreases in 20% and 40%-EtOH/DMA with increasing temperature, while it increases in 60%-EtOH/DMA. The temperature dependence of the CO/HCOO−selectivity indicates that the difference in activation energy (ΔΔG‡) between CO and HCOO−production is estimated asca.3.06 kJ mol−1in 40%-EtOH/DMA at 298 K.

Hemolytic decomposition of di-sec-butyl peroxide

1970 ◽  
Vol 48 (4) ◽  
pp. 615-627 ◽  
Author(s):  
R. Hiatt ◽  
Sandor Szilagyi
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Hydrogen Production ◽  
Methyl Ethyl Ketone ◽  
Methyl Ethyl ◽  
Kcal Mole ◽  
Alkoxy Radicals ◽  
Solvent Cage ◽  
Butyl Peroxide

Rates and products have been determined for the thermal decomposition of sec-butyl peroxide at 110–150 °C in several solvents.The decomposition was shown to be unimolecular with energies of activation in toluene, benzene, and cyclohexane of 35.5 ± 1.0, 33.2 ± 1.0, 33.8 ± 1.0 kcal/mole respectively. The activation energy of thermal decomposition for the deuterated peroxide was found to be 37.2 + 1.0 kcal/mole in toluene.About 70–80% of the products could be explained by known reactions of free alkoxy radicals, and very little, if any, disproportionation of two sec-butoxy radicals in the solvent cage could be detected.The other 20–30% of the peroxide yielded H2 and methyl ethyl ketone. The yield of H2 was unaffected by the nature or the viscosity of the solvent, but H2 was not formed when s-Bu2O2 was photolyzed in toluene at 35 °C nor when the peroxide was thermally decomposed in the gas phase.α,α′-Dideutero-sec-butyl peroxide was prepared and decomposed in toluene at 110–150 °C. The yield of D2 was about the same as the yield of H2 from s-Bu2O2, but the rate of decomposition (at 135 °C) was only 1/1.55 as fast.Mechanisms for hydrogen production are discussed, but none satisfactorily explains all the evidence.

THE PHOTOLYSIS OF AZOISOPROPANE

1953 ◽  
Vol 31 (4) ◽  
pp. 377-384 ◽  
Author(s):  
R. W. Durham ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Excited Molecule ◽  
Energy Difference ◽  
Effect Of Pressure ◽  
Temperature Range ◽  
Excited Molecules

Azoisopropane has been photolyzed by 3600 Å radiation over the temperature range 30–120 °C. The effect of pressure indicates an excited molecule mechanism. Excited molecules which decompose give nitrogen and isopropyl radicals; the latter either combine, disproportionate, or react with azoisopropane. The activation energy difference between the two reactions[Formula: see text]has been found to be 6.5 ± 0.5 kcal. per mole.The difference in activation energy between the disproportionation and combination reactions is rendered ambiguous by the possibility of C3H7.N:N existing at the lower temperatures; but this is certainly small. The ratio of the rates of the two reactions is 0.5 at room temperature.

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.

Reactions of Alkoxy Radicals. I. The Reactions of Di-tert.-butyl Peroxide with n-Butyric Acid and Ethyl n-Butyrate

1960 ◽  
Vol 13 (2) ◽  
pp. 244 ◽  
Author(s):  
ALJ Beckwith
Keyword(s):  
Butyric Acid ◽  
Electron Acceptor ◽  
Dicarboxylic Acids ◽  
Cupric Chloride ◽  
Hydrogen Atoms ◽  
Alkoxy Radicals ◽  
Tert Butyl ◽  
Butyl Peroxide ◽  
Butoxy Radical

The relative yields of meso- and racernic-2,3-diethylsucoinic and 2-ethyl-3-methyl-glutaric acids from the reaction of di-tert.-butyl peroxide with n-butyric acid indicate that abstraction of hydrogen atoms from the acid by tert.-butoxy radicals occurs preferentially at the α-position. A similar directive effect has been noted in the reaction of ethyl n-butyrate with di-tert.-butyl peroxide. These results suggest that the tert.-butoxy radical has negligible electron-acceptor properties and that polar effects do not influence the course of its reactions. Catalytic amounts of cupric chloride profoundly modify the reaction of di-tert.-butyl peroxide with n-butyric acid. New analytical methods for the separation and determination of hydroxy- and dicarboxylic acids are described.

THE OXIDATION OF DI-tertiary-BUTYL PEROXIDE

1961 ◽  
Vol 39 (2) ◽  
pp. 278-284 ◽  
Author(s):  
A. R. Blake ◽  
K. O. Kutschke
Keyword(s):  
Carbon Monoxide ◽  
Major Product ◽  
Static System ◽  
Peroxy Radicals ◽  
Tertiary Butyl ◽  
Stationary Concentration ◽  
Methyl Hydroperoxide ◽  
Butyl Peroxide ◽  
High Yields ◽  
Butoxy Radical

The oxidation of di-t-butyl peroxide has been investigated in a static system at low conversion at 124 °C with sufficient oxygen present to suppress completely the formation of methane and ethane. The decomposition of the t-butoxy radical is unaffected by the presence of oxygen. A major product of the oxidation is formaldehyde whose yield rapidly approaches a stationary value. It is postulated that the major source of formaldehyde is the decomposition of methyl peroxy radicals, which may also abstract hydrogen from formaldehyde to form methyl hydroperoxide, and that this competition leads to the stationary concentration of formaldehyde actually observed. Methyl hydroperoxide was demonstrated to be unstable in the system and the predominant decomposition product was methanol, a compound also found in high yields in the oxidation. Experiments with added formaldehyde-C13 showed that formaldehyde can be converted to carbon monoxide in the system and indicated that formaldehyde was a likely precursor to the carbon monoxide found in the oxidation.

Kinetics of carbon monoxide methanation on a Ni/SiO2 catalyst

1990 ◽  
Vol 55 (7) ◽  
pp. 1678-1685
Author(s):  
Vladimír Stuchlý ◽  
Karel Klusáček
Keyword(s):  
Carbon Monoxide ◽  
Reaction Rate ◽  
Catalyst Activity ◽  
Adsorbed Hydrogen ◽  
Reaction Products ◽  
Co Methanation ◽  
Molar Ratios ◽  
Rate Determining Step ◽  
Higher Temperature ◽  
Kinetics Of

Kinetics of CO methanation on a commercial Ni/SiO2 catalyst was evaluated at atmospheric pressure, between 528 and 550 K and for hydrogen to carbon monoxide molar ratios ranging from 3 : 1 to 200 : 1. The effect of reaction products on the reaction rate was also examined. Below 550 K, only methane was selectively formed. Above this temperature, the formation of carbon dioxide was also observed. The experimental data could be described by two modified Langmuir-Hinshelwood kinetic models, based on hydrogenation of surface CO by molecularly or by dissociatively adsorbed hydrogen in the rate-determining step. Water reversibly lowered catalyst activity and its effect was more pronounced at higher temperature.

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