Photosensitization by Cd(3P0,1) atoms. III. Gas phase decomposition of cyclopentane

1976 ◽  
Vol 54 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Bansi L. Kalra ◽  
Arthur R. Knight
Keyword(s):  
Gas Phase ◽  
Vapor Phase ◽  
Product Formation ◽  
Time Dependent ◽  
Primary Process ◽  
Phase Decomposition ◽  
Unimolecular Decomposition ◽  
Hydrogen Atoms ◽  
Volatile Products ◽  
Radical Decomposition

The triplet cadmium photosensitized decomposition of cyclopentane in the vapor phase has been studied at 355 °C and has been shown to give rise to cyclopentyl radicals and hydrogen atoms with close to unit efficiency in the primary process. Subsequent reactions of these species, including an important contribution from unimolecular decomposition of cyclopentyl radicals, yield the observed volatile products, hydrogen, methane, ethylene, ethane, propylene, and cyclopentene. As a result of significant olefin scavenging of H-atoms product yields are strongly time dependent. The system has been shown to be unaffected by addends. The temperature dependence of the rate of product formation is consistent with the known energetics of cyclopentyl radical decomposition.

Photosensitization by Cd(3P1) Atoms. II. Gas Phase Decomposition of Cyclohexane

1972 ◽  
Vol 50 (13) ◽  
pp. 2010-2016 ◽  
Author(s):  
B. L. Kalra ◽  
A. R. Knight
Keyword(s):  
Quantum Yield ◽  
Gas Phase ◽  
Vapor Phase ◽  
Exposure Time ◽  
Molecular Hydrogen ◽  
Primary Decomposition ◽  
Phase Decomposition ◽  
Hydrogen Atoms ◽  
Hydrogen Formation ◽  
Volatile Products

The photodecomposition of cyclohexane sensitized by Cd(3P1) atoms has been studied in the vapor phase at 355 °C. The primary decomposition gives hydrogen atoms and cyclohexyl radicals. The volatile products of the decomposition are H2, cyclohexene, propylene, ethane, ethylene, methane, propane, butadiene, and methylcyclopentane. Products other than H2 and cyclo-C6H10 arise from unimolecular reactions of cyclohexyl radicals, the most important such process being the production of propylene and allyl radicals. Hydrogen yields decrease rapidly with time because of H-atom scavenging reactions involving olefinic products. The quantum yield of molecular hydrogen formation at the shortest exposure time examined is 0.53.

The gas-phase decomposition of ethyl bromide

1971 ◽  
Vol 24 (10) ◽  
pp. 2031
Author(s):  
DA Kairaitis ◽  
VR Stimson
Keyword(s):  
Gas Phase ◽  
Initial Rate ◽  
Hydrogen Bromide ◽  
Bromine Atom ◽  
Ethyl Bromide ◽  
Phase Decomposition ◽  
Unimolecular Decomposition ◽  
Chain Reaction ◽  
Insight Into

The gas-phase decomposition of ethyl bromide at 423� in the presence of both ethylene and hydrogen bromide has been investigated. These additives, which are also the products, each influence the rate strongly but in opposite ways. The variation of initial rate with reactant pressure is given by (P in cm) ������������� k1 (min-1) = 15.2x10-3+19.5x10-3(PEtBrPHBr/PEne)1/2 This has been interpreted in terms of a unimolecular decomposition together with a bromine atom carried chain reaction with simple steps that involve the products. Some insight into the unaccompanied decomposition has been gained. Some remarks about the role of olefinic inhibitors in reactions producing hydrogen bromide have been made.

Reaction of methyl radicals with cis-butene-2

1969 ◽  
Vol 47 (16) ◽  
pp. 2987-3001 ◽  
Author(s):  
Nobuo Yokoyama ◽  
R. K. Brinton
Keyword(s):  
Gas Phase ◽  
Equilibrium Distribution ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Hydrogen Atoms ◽  
Radical Concentration ◽  
Radical Decomposition ◽  
Similar Temperature ◽  
Carbonyl Radical

Methyl radicals generated by di-t-butylperoxide pyrolysis interact at comparable rates with cis-butene-2 in the gas phase by both addition and hydrogen atom abstraction. The determination of the rate of these reactions was simplified by the addition of a large concentration of acetaldehyde to the system. The additive, a source of low activation energy abstractable hydrogen atoms, was effective in suppressing polymerization reactions, and in addition, maintained a high steady state methyl radical concentration as a result of the carbonyl radical decomposition. The rate constants, k5 and k6 for the reactions [5] and [6], were determined to be 4.5 × 1010exp (−7000/RT)and 1.8 × 1010exp (−7300/RT)[Formula: see text]cm3 mole−1 s−1, respectively, over the temperature range 126–163 °C. The butenyl radical formed in reaction [6] isomerizes much faster than its interaction with other species in the system, and the distribution of the various conformations is similar to the equilibrium distribution of the butenes at a similar temperature.

Gas phase photolysis of 1-pentene and 1-pentene-d10 at 7.1 and 7.6 eV. Kinetic considerations

1978 ◽  
Vol 56 (10) ◽  
pp. 1435-1441 ◽  
Author(s):  
Andrzej Więckowski ◽  
Guy J. Collin
Keyword(s):  
Gas Phase ◽  
Isotope Effects ◽  
Distribution Functions ◽  
Static System ◽  
Hydrogen Atoms ◽  
Photochemical Process ◽  
Radical Decomposition ◽  
Energy Distribution Functions ◽  
Kinetics Of ◽  
Non Equilibrium

The gas phase photolysis of n-pentene was carried out in a static system using nitrogen resonance lines at [Formula: see text] and the bromine line at [Formula: see text] The mechanism for the photolysis was proposed and compared to what was concluded at 8.4 eV (147 nm, the xenon resonance line). The kinetics of the decomposition of the excited C3H5* radicals formed in the primary photochemical process and the C5H11* radicals formed by the addition of hydrogen atoms to the parent molecules were discussed. The investigations were extended to the n-C5D10 photolytic System. The observed decomposition rate constants of the excited pentyl radicals as well as the secondary non-equilibrium isotope effects agree with the data published earlier. It is concluded from these experiments that, at least at 7.6 eV, hot hydrogen atoms are produced.Only a small fraction of the C3H5* radicals décompose and yield aliène. At the same time the combined primary–secondary non-equilibrium isotope effects are much less than those calculated for the 'pure' primary isotope effects. To account for these observations, it is assumed that the C3H5* radicals are formed with a wide spread in the internal energies. Since the threshold of the decomposition of the excited C3H5* radical lies above its mean excess energy (calculated on the statistical basis), an analogy in the energy-distribution functions on the radicals activated photochemically and thermally may be suggested. If so, an inverse secondary isotope effect may contribute to the gross effect involved in the C3H5* radical decomposition.

The role of excited states in the gas-phase photolysis of acetaldehyde

1973 ◽  
Vol 334 (1598) ◽  
pp. 411-426 ◽  
Keyword(s):  
Triplet State ◽  
Gas Phase ◽  
Excited States ◽  
Product Formation ◽  
Vibrationally Excited ◽  
Liquid Phases ◽  
Radical Decomposition ◽  
A Chain ◽  
Low Pressures

The cis-trans isomerization of butene-2 has been used to measure the triplet state yields in the photolysis of acetaldehyde at various wavelengths between 313 and 254 nm over the temperature range 35 to 140 °C. The results, together with those derived from chemical product formation, are consistent with data from luminescence studies. Dissociation into molecular products occurs rapidly, probably by predissociation, from a non-quenchable excited state formed by absorption. The main free radical decomposition occurs from the triplet state and this, in the absence of additives, such as butene-2, is responsible for the chain decomposition. The intersystem crossing and non-quenchable processes are independent of temperature. Isopentyl radicals formed from methyl addition to butene-2 can also propagate a chain reaction for acetaldehyde decomposition. At high temperatures and low pressures, dissociation of vibrationally excited isopentyl radicals can contribute to the measured isomerization yield. This is shown by the effect of addition of inert gas. Evidence is put forward that geometrical isomerization of the olefin involves a triplet aldehyde-olefin complex that can be decomposed by collision with ground state aldehyde molecules without cis-trans rearrangement of the olefin. This conclusion is consistent with other work in the gas and liquid phases.

A vibrational spectroscopic and computational study of the structures of protonated imidacloprid and its fragmentation products in the gas phase

2021 ◽  
Vol 23 (5) ◽  
pp. 3377-3388
Author(s):  
Kelsey J. Menard ◽  
Jonathan Martens ◽  
Travis D. Fridgen
Keyword(s):  
Computational Chemistry ◽  
Gas Phase ◽  
Vibrational Spectroscopy ◽  
Computational Study ◽  
Unimolecular Decomposition ◽  
Decomposition Products

Vibrational spectroscopy and computational chemistry studies were combined with the aim of elucidating the structures of protonated imidacloprid (pIMI), and its unimolecular decomposition products.

Unimolecular decomposition of methylsubstituted benzenes into benzyl radicals and hydrogen atoms

1990 ◽  
Vol 93 (8) ◽  
pp. 5700-5708 ◽  
Author(s):  
Jeunghee Park ◽  
Richard Bersohn ◽  
Izhack Oref
Keyword(s):  
Unimolecular Decomposition ◽  
Hydrogen Atoms ◽  
Benzyl Radicals

A Combined Experimental and Theoretical Study of the Homogeneous, Unimolecular Decomposition Kinetics of 3-Chloropivalic Acid in the Gas Phase

2001 ◽  
Vol 105 (10) ◽  
pp. 1869-1875 ◽  
Author(s):  
Gabriel Chuchani ◽  
Alexandra Rotinov ◽  
Juan Andrés ◽  
Luís R. Domingo ◽  
V. Sixte Safont
Keyword(s):  
Gas Phase ◽  
Theoretical Study ◽  
Decomposition Kinetics ◽  
Unimolecular Decomposition ◽  
Kinetics Of

The kinetics of the gas phase decomposition reactions of the hexafluoro-t-butoxy radical

1983 ◽  
Vol 15 (3) ◽  
pp. 293-303 ◽  
Author(s):  
Roger M. Drew ◽  
J. Alistair Kerr
Keyword(s):  
Gas Phase ◽  
Phase Decomposition ◽  
Decomposition Reactions ◽  
Butoxy Radical ◽  
Kinetics Of
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