Reactions of acetyl and methyl radicals with nitric oxide

1969 ◽  
Vol 73 (10) ◽  
pp. 3498-3499 ◽  
Author(s):  
Harold E. Avery ◽  
D. M. Hayes ◽  
Leslie Phillips
Keyword(s):  
Nitric Oxide ◽  
Methyl Radicals

The Reaction of Methyl Radicals with Nitric Oxide

1964 ◽  
Vol 86 (10) ◽  
pp. 1929-1934 ◽  
Author(s):  
A. Maschke ◽  
B. S. Shapiro ◽  
F. W. Lampe
Keyword(s):  
Nitric Oxide ◽  
Methyl Radicals

The photolysis and pyrolysis of nitromethane and methyl nitrite

1967 ◽  
Vol 299 (1458) ◽  
pp. 317-336 ◽  
Keyword(s):  
Nitric Oxide ◽  
Nitrogen Dioxide ◽  
Elevated Temperatures ◽  
Flash Photolysis ◽  
Stable Form ◽  
Methyl Radicals ◽  
Elimination Reaction ◽  
Kinetic Spectroscopy ◽  
Methyl Nitrite ◽  
A Minor

The photolysis and pyrolysis of nitromethane and methyl nitrite have been studied using the techniques of flash photolysis and kinetic spectroscopy. The results show that photolysis of nitromethane yields methyl radicals and nitrogen dioxide, and that these fragments undergo recombination and disproportionation reactions to form methyl nitrite, methoxyl, and nitric oxide. In the presence of added nitric oxide, the methyl radicals react principally with nitric oxide to form nitrosomethane, which subsequently dimerizes and also reacts further with nitric oxide to yield nitrogen dioxide. The evidence also suggests that nitrosomethane is removed by a relatively efficient reaction with nitrogen dioxide at elevated temperatures to produce nitromethane and nitric oxide. In the case of methyl nitrite, light absorption results not only in photolysis, but also in the formation of an isomer of the nitrite which then reverts slowly to the stable form. The nature of this isomer is not known, but possibilities are suggested and discussed. It is concluded that the decomposition (photolytic or pyrolytic) of methyl nitrite occurs by the rupture of the O—N bond, and that the methoxyl radicals formed disproportionate to yield methanol and form aldehyde. Nitroxyl is also formed but only as a minor product, and the marked increase in intensity of its spectrum in the presence of added nitric oxide shows that it is not formed by a molecular elimination reaction, but probably by CH 3 O + NO → CH 2 O + HNO.

The photochemical decomposition of methyl iodide in presence of nitric oxide I. The reaction of methyl radicals with nitric oxide

1959 ◽  
Vol 249 (1257) ◽  
pp. 248-257 ◽  
Keyword(s):  
Nitric Oxide ◽  
Methyl Iodide ◽  
Molecular Iodine ◽  
Gas Mixture ◽  
Methyl Radicals ◽  
Third Order ◽  
Absolute Value ◽  
Uncertainty Factor ◽  
Photochemical Decomposition ◽  
Limiting Value

The quantum yield of molecular iodine produced in the photolysis of gaseous methyl iodide is markedly increased by the presence of small quantities of nitric oxide. The yield of iodine is determined by the competition between reactions of methyl radicals with iodine molecules to reform methyl iodide and of methyl radicals with nitric oxide to form nitrosomethane. The latter reaction is pressure-dependent and the kinetics may be interpreted in terms of the following steps: CH 3 + NO = CH 3 NO' ( k a ). CH 3 NO' = CH 3 + NO ( k b ), CH 3 NO' + M = CH 3 NO + M' ( k c,M ). The apparent third-order constant at low pressure { = ( k c, M k a ) / k b } is 50 times as great as that measured for the association of methyl radicals with oxygen in the same gas mixture. The minimum lifetime of the energy-rich CH 3 NO' complex is 10 -8 s. The absolute value of k a , the limiting value of the apparent second-order constant for the association, is estimated to be 7 x 10 11 ml. mole -1 s -1 , with an uncertainty factor of 3.

Derivation of rate constants for steps in the free-radical chain decomposition of paraffins

1962 ◽  
Vol 268 (1332) ◽  
pp. 36-45 ◽  
Keyword(s):  
Nitric Oxide ◽  
Free Radical ◽  
Rate Constants ◽  
High Pressures ◽  
Radical Mechanism ◽  
Methyl Radicals ◽  
Saturated Hydrocarbons ◽  
Radical Chain ◽  
Free Radical Mechanism ◽  
Standard Values

The Rice-Herzfeld free-radical mechanism for the thermal decomposition of saturated hydrocarbons, including both the uninhibited reaction and that partially inhibited by nitric oxide, involves the rate constants of various individual steps. If standard values are assumed for the rate constants of H -abstraction from n -pentane by methyl radicals, alkyl radical recombination, and addition of methyl to nitric oxide, then those of all the steps for a series of paraffins can be found. The method depends on measurements of the rate constant in the region where the chain reaction is of the first order, the inhibitory action of nitric oxide as a function of paraffin pressure, and the acceleration of paraffin decomposition rate produced by high pressures of nitric oxide. Values are derived for propane, three pentanes ( neo -, iso - and normal pentane) and three octanes ( normal octane, 2:3:4-trimethyl pentane and 2:2:4-trimethyl pentane), and the variations of the several rate constants with structure are discussed.

The photochemical decomposition of methyl iodide in presence of nitric oxide - II. Reactions of nitrosomethane

1959 ◽  
Vol 249 (1257) ◽  
pp. 258-269 ◽  
Keyword(s):  
Nitric Oxide ◽  
Gas Phase ◽  
Methyl Iodide ◽  
Initial Rate ◽  
Wavelength Region ◽  
Order Reaction ◽  
Methyl Radicals ◽  
Second Order Reaction ◽  
Photochemical Decomposition ◽  
Rate Method

A product of the photolysis, in presence of a small quantity of nitric oxide, of methyl iodide reacts with excess nitric oxide to form a substance(s), Y , which absorbs light throughout the wavelength region 2300 to 5300 Å. The initial products of the photolysis, in presence of small quantities of nitric oxide, of both acetone and acetaldehyde react similarly. The species undergoing the reaction is believed to be monomeric nitrosomethane, formed by the association of methyl radicals with nitric oxide. The order of the reaction to form Y , as determined by the initial rate method, is one with respect to nitrosomethane and two with respect to nitric oxide. The extent of the reaction, which can be used as a measure of nitrosomethane concentration, depends on the concentration of nitric oxide. In absence of excess nitric oxide the monomer disappears slowly from the gas phase in a second-order reaction, which is thought to be the dimerization to nitrosomethane dimer.

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