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

ChemInform Abstract: Unimolecular Decomposition of Methylsubstituted Benzenes into Benzyl Radicals and Hydrogen Atoms

ChemInform ◽  
2010 ◽  
Vol 22 (8) ◽  
pp. no-no
Author(s):  
J. PARK ◽  
R. BERSOHN ◽  
I. OREF
Keyword(s):  
Unimolecular Decomposition ◽  
Hydrogen Atoms ◽  
Benzyl Radicals

Reactions of free radicals with aromatic compounds in the gaseous phase. I. Kinetics of the reaction of methyl radicals with toluene

1964 ◽  
Vol 17 (12) ◽  
pp. 1329 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams ◽  
JR Wilmshurst
Keyword(s):  
Flow System ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Hydrogen Atoms ◽  
Methyl Group ◽  
Benzyl Radical ◽  
Toluene Molecule ◽  
Benzyl Radicals ◽  
Butyl Peroxide ◽  
Kinetics Of

The kinetics of abstraction of hydrogen atoms from the methyl group of the toluene molecule by methyl radicals at 430-540�K have been determined. The methyl radicals were produced by pyrolysis of di-t-butyl peroxide in a stirred-flow system. The kinetics ,agree substantially with those obtained by previous authors using photolytic methods for generating the methyl radicals. At toluene and methyl-radical concentrations of about 5 x 10-7 and 10-11 mole cm-3 respectively the benzyl radicals resulting from the abstraction disappear almost entirely by combination with methyl radicals at the methylenic position. In this respect the benzyl radical behaves differently from the iso-electronic phenoxy radical, which previous work has shown to combine with a methyl radical mainly at ring positions. The investigation illustrates the application of stirred-flow technique to the study of the kinetics of free-radical reactions.

The non-isothermal oxidation of 2 -methylpentane. - III. The reaction at high pressure

1969 ◽  
Vol 313 (1513) ◽  
pp. 261-297 ◽  
Keyword(s):  
High Temperatures ◽  
Isothermal Oxidation ◽  
Gas Liquid Chromatography ◽  
Labile Hydrogen ◽  
Chain Process ◽  
Unimolecular Decomposition ◽  
Hydrogen Atoms ◽  
Radical Chain ◽  
Cool Flame ◽  
Alkylperoxy Radicals

The non-isothermal oxidation of 2-methylpentane has been studied at pressures of 1-4 MN m -2 and temperatures of 440 to 660 °C in an arrested-piston rapid-compression machine. The variations with pressure and temperature of the induction periods leading to cool-flame reaction and hot ignition have been determined, and the products of the reaction have been analysed by gas-liquid chromatography. At high temperatures and pressures the cool-flame reaction occurs by a free-radical chain process in which homogeneous isomerization and subsequent decomposition of alkylperoxy radicals propagate the chain. The resulting propa­gation cycle is substantially the same as that which has been established at lower tempera­tures and subatmospheric pressures. At high temperatures and pressures the reaction is, however, even more unselective, and oxidation of β -hydroperoxyalkyl radicals competes more successfully with their unimolecular decomposition, thus leading to the formation of β -ketoaldehydes. These compounds, together with the conjugated unsaturated carbonyl compounds, account quantitatively for the absorption of ultraviolet light by reacting 2-methylpentane/air mixtures. The mechanism of chain branching in the cool-flame reaction probably involves the pyrolysis of hydroperoxides. In the second stage of two-stage ignition, the propagation cycle is the same as that occurring in the cool flame but the important difference is that the cool flame has formed substantial concentrations of compounds with labile hydrogen atoms; these react readily with alkylperoxy radicals to form hydroperoxides, the pyrolysis of which again branches the chain.

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.

The reactions of benzyl radicals with hydrogen atoms, oxygen atoms, and molecular oxygen using EI/REMPI mass spectrometry

1989 ◽  
Vol 22 (1) ◽  
pp. 1041-1051 ◽  
Author(s):  
M. Bartels ◽  
J. Edelbüttel-Einhaus ◽  
K. Hoyermann
Keyword(s):  
Mass Spectrometry ◽  
Molecular Oxygen ◽  
Hydrogen Atoms ◽  
Benzyl Radicals ◽  
Oxygen Atoms

Photochemical studies of unimolecular processes III. Subsidiary processes in the photolysis of cycloheptatriene

1970 ◽  
Vol 316 (1524) ◽  
pp. 143-151 ◽  
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Hydrogen Atoms ◽  
Vibrationally Excited ◽  
Sufficient Energy ◽  
Benzyl Radicals

In addition to toluene, the photolysis of cyclo[l. 3. 5]heptatriene (CHT) in the gas phase yields small amounts of benzene, methane, ethane, cyclopentadiene and acetylene. Most of the toluene molecules formed by the photo-isomerization of CHT have sufficient energy to dissociate to benzyl radicals and hydrogen atoms; the small fraction which do are responsible for the first three minor products. Cyclopentadiene and acetylene arise from vibrationally excited ground state CHT molecules with energies greater than 268 ± 12 kJ/mol, bicyclo[2. 2. l]heptadiene being the intermediate involved.

Remarks on the diffuse interstellar lines

1967 ◽  
Vol 31 ◽  
pp. 91-93 ◽  
Author(s):  
G. Herzberg
Keyword(s):  
Hydrogen Atoms ◽  
Interstellar Gas

It is suggested that the diffuse interstellar lines are produced in the interstellar gas by molecules consisting of a few hydrogen atoms and one other atom, such as CH4+ or NH4. Diffuseness of the lines is assumed to result from predissociation of these molecules.

The broadening of strong lines of Ca+, Mg+ and Ba+ by collisions with neutral hydrogen atoms

1998 ◽  
Vol 300 (3) ◽  
pp. 863-871 ◽  
Author(s):  
P. S. Barklem ◽  
B. J. O'Mara
Keyword(s):  
Neutral Hydrogen ◽  
Hydrogen Atoms
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