Kinetics of free radicals generated by IR laser photolysis. IV. Intersystem crossings and reactions of C2(X 1Σ+g) and C2(a 3Πu) in the gaseous phase

1980 ◽  
Vol 73 (5) ◽  
pp. 2280-2286 ◽  
Author(s):  
H. Reisler ◽  
M. S. Mangir ◽  
C. Wittig
Keyword(s):  
Free Radicals ◽  
Gaseous Phase ◽  
Laser Photolysis ◽  
Ir Laser ◽  
Kinetics Of

Kinetics of polyatomic free radicals produced by laser photolysis. 4. Study of the equilibrium isopropyl + oxygen .tautm. isopropylperoxy between 592 and 692 K

1985 ◽  
Vol 107 (7) ◽  
pp. 1838-1845 ◽  
Author(s):  
Irene R. Slagle ◽  
Emil Ratajczak ◽  
Michael C. Heaven ◽  
David Gutman ◽  
Albert F. Wagner
Keyword(s):  
Free Radicals ◽  
Laser Photolysis ◽  
Kinetics Of

Kinetics of polyatomic free radicals produced by laser photolysis. 3. Reaction of vinyl radicals with molecular oxygen

1984 ◽  
Vol 106 (16) ◽  
pp. 4356-4361 ◽  
Author(s):  
Irene R. Slagle ◽  
Jong Yoon Park ◽  
Michael C. Heaven ◽  
David Gutman
Keyword(s):  
Free Radicals ◽  
Molecular Oxygen ◽  
Laser Photolysis ◽  
Vinyl Radicals ◽  
Kinetics Of

Reactions of free radicals with aromatic compounds in the gaseous phase. II. Kinetics of the reaction of methyl radicals with phenol

1965 ◽  
Vol 18 (1) ◽  
pp. 20 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams
Keyword(s):  
Free Radicals ◽  
Gaseous Phase ◽  
Hydrogen Abstraction ◽  
High Reactivity ◽  
Phenoxy Radical ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Kinetics Of Formation ◽  
Phenolic Substances ◽  
Kinetics Of

Knowledge of the reactivity of phenols towards simple free radicals is needed to throw light on the behaviour of the phenolic substances involved in the pyrolysis of coal and other organic materials. In the present investigation the reaction between methyl radicals and phenol vapour has been studied a t total pressures from 0.5 to 3 cmHg and temperatures from 445 to 547°K, the concentrations of methyl radicals and phenol being varied from 2 × 10-12 to 4 × 10-11 and 1 × 10-8 to 8 × 10-7 mole cm-3 respectively. The main products identified by gas chromatography were methane and o- and p-cresol, together with a little anisole and 2,4- and 2,6-dimethylphenol. The cresols are produced via hydrogen abstraction Diagram followed by combination of a methyl radical at a ring position of the phenoxy radical either ortho or para to the oxygen atom, e.g. in the case of the para position: Diagram The kinetics can be explained by postulating (a) that the keto forms of the cresols (methylcyclohexadienones) formed initially by reaction (6) have a finite lifetime in the gaseous phase and (b) that these molecules, which contain a tertiary hydrogen atom α to a system of a carbonyl bond and two carbon-carbon double bonds, partly undergo hydrogen abstraction by methyl radicals before they are able to enolize: CH3· + (HCH3 = C6H4 = O → CH4 + CH3C6H4O· The mechanism is consistent with the kinetics of formation of methane, the distribu- tion of the free electron in the phenoxy radical, the formation of o- and p-cresols as major products, the kinetics of formation of the cresols, and the high reactivity of the intermediate product towards methyl radicals.

THE PHOTOCHEMICAL OXIDATION OF ALDEHYDES IN THE GASEOUS PHASE: PART II. THE KINETICS OF THE PHOTOCHEMICAL OXIDATION OF PROPIONALDEHYDE

1958 ◽  
Vol 36 (1) ◽  
pp. 258-267 ◽  
Author(s):  
C. A. McDowell ◽  
L. K. Sharples
Keyword(s):  
Free Radicals ◽  
Excited States ◽  
Gaseous Phase ◽  
Photochemical Oxidation ◽  
Radical Process ◽  
Velocity Constant ◽  
Absorption Of Light ◽  
Oxidation Chain ◽  
Kinetics Of ◽  
Free Radical Process

The photochemical oxidation of propionaldehyde has been studied in the gaseous phase at 23 °C. and a wavelength of 3130 Å. With pressures of oxygen varying from 0.3 mm. to 100 mm. Hg it has been established that the reaction obeys the same kinetic law as that found for the corresponding reaction with acetaldehyde, namely:[Formula: see text]where k3 is the velocity constant for the propagating reaction [3]:[Formula: see text]and k6 is the velocity constant for the terminating reaction [6]:[Formula: see text][Formula: see text]is the rate of initiation and it is regarded as being a composite quantity representing the rate of formation of propionyl radicals, which are thought to be the initiators of the oxidation chain. The propionyl radicals are thought to be formed by two processes: (a) from the subsequent reactions of free radicals produced in the primary free radical process which occurs when propionaldehyde absorbs a quantum of radiation at 3130 Å, and (b) from the subsequent reactions, with oxygen, of excited states of propionaldehyde, which are also thought to be formed by the absorption of light of wavelength 3130 Å.

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