Reaction of Phenoxy Radicals with Methyl Radicals in the Gaseous Phase

Nature ◽  
1963 ◽  
Vol 199 (4895) ◽  
pp. 761-762 ◽  
Author(s):  
M. F. R. MULCAHY ◽  
D. J. WILLIAMS
Keyword(s):  
Gaseous Phase ◽  
Methyl Radicals ◽  
Phenoxy Radicals

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.

Reactions of free radicals with aromatic compounds in the gaseous phase. III. Kinetics of the reaction of methyl radicals with anisole (methoxybenzene)

1967 ◽  
Vol 20 (6) ◽  
pp. 1155 ◽  
Author(s):  
MFR Mulcahy ◽  
BG Tucker ◽  
DJ Williams ◽  
JR Wilmshurst
Keyword(s):  
Free Radicals ◽  
Gaseous Phase ◽  
Aromatic Compounds ◽  
Phase Iii ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Rate Of Reaction ◽  
Reaction Proceeds ◽  
Kinetics Of Reaction ◽  
Kinetics Of

The kinetics of the reaction between methyl radicals and anisole have been studied at temperatures between 453 and 539�K and total pressures between 10 and 30 torr. The concentrations of methyl radicals ranged from 2 x 10-12 to 5 x 10-11 mole and those of anisole from 10-7 to mole cm-3. The reaction proceeds mainly by the mechanism ������������������ C6H5OCH3+CH3· → C6H5OCH2·+CH4���������������� (1)����������������� C6H5OCH2·+CH3· → C6H5OC2H5�������������������� (2)���������������� ���������C6H5OCH2· → C6H5CHO+H·������������������ (3) At 487�K attack on the aromatic ring to yield methyl anisoles is about twelve times slower than reaction (1). The Arrhenius parameters for reactions (1) and (8) are: log10(A1 cm3 mole-1 sec-1) = 11.7 � 0.3, and E1 = 10.5 � 0.8 kcal mole-1; log10(A8 sec-1) = 12.5, and E8 = 21 kcal mole-1. The last two values are based on the assumption that the kinetics of reaction (2) are similar to those of the recombination of methyl radicals. The rate of reaction (1) is about half that of the corre- sponding reaction with toluene and about five times that of the reaction with ethane in the above temperature range.

Intercalation of uranium hexafluoride into graphite

1985 ◽  
Vol 50 (4) ◽  
pp. 947-955 ◽  
Author(s):  
Karel Klouda ◽  
Václav Rak ◽  
Josef Vachuška
Keyword(s):  
Carbon Atom ◽  
Surface Area ◽  
Gaseous Phase ◽  
Uranium Hexafluoride ◽  
Graphite Particles ◽  
Fluorination Agent ◽  
Increasing Temperature ◽  
Elementary Fluorine

Intercalation of UF6 into graphite, both from the gaseous phase and from the Ledon 113 solution, was studied. The amount of intercalated UF6 from the gaseous phase was found to be inversely proportional to the size of graphite particles. Intercalation increases with the increasing temperature and surface area of graphite. The contact of gaseous UF6 with graphite led to the formation of β-UF5 that is not intercalated. In the Ledon solution, β-UF5 is not formed. "Passivation" of graphite by elementary fluorine also prevents the formation of β-UF5 but the amount of intercalated UF6 decreases. The intercalation of UF6 into graphite from the gaseous phase is accompanied by the increase of the distance between the parallel carbon atom layers up to the values of about 884 pm. Ternary intercalates graphite-UF6-Ledon 113 are formed during the intercalation of UF6 from the Ledon 113 solutions and the distance between the parallel carbon atom layers is 848-875 pm. Thermogravimetry in the presence of air revealed that the binary intercalates graphite-UF6 decompose in a 3-step reaction while the ternary intercalates decompose in a 4-step reaction. In both cases uranium hexafluoride is not released but acts as a fluorination agent on the graphite carbon.

Photoionization of two substituted methyl radicals: Cyanomethyl and bromomethyl

2010 ◽  
Vol 500 (4-6) ◽  
pp. 232-236 ◽  
Author(s):  
Michael Steinbauer ◽  
Patrick Hemberger ◽  
Ingo Fischer ◽  
Melanie Johnson ◽  
Andras Bodi
Keyword(s):  
Methyl Radicals
Sign in / Sign up

Export Citation Format

Share Document