The kinetics of the interaction of atomic hydrogen with olefines. V. Results obtained for a further series of compounds

1950 ◽  
Vol 202 (1069) ◽  
pp. 181-202 ◽  
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Atomic Hydrogen ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Alkyl Radicals ◽  
Kinetics Of ◽  
Interesting Generalization

In this paper the efficiency of interaction of a hydrogen atom with a series of olefines has been determined, the olefines being members of the series obtained by progressively replacing the hydrogen atoms of ethylene by methyl radicals. The interesting generalization which emerges from this is that the efficiency of interaction does not vary very much with the nature of the alkyl substituents in the molecule, and calculations involving the heats of addition of a hydrogen atom to a double bond confirm this generalization. The data presented here are discussed critically in relation to information available on the reaction of CCl 3 radicals with olefines and of alkyl radicals with olefines, complete general agreement being demonstrated.

scholarly journals The kinetics of the interaction of atomic hydrogen with olefines III. Theory and technique involved in the use of the oxides of molybdenum and tungsten as hydrogen atom removers

1949 ◽  
Vol 196 (1047) ◽  
pp. 479-493 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Molybdenum Oxide ◽  
Atomic Hydrogen ◽  
Colorimetric Method ◽  
Oxide Surface ◽  
Hydrogen Atoms ◽  
Alkyl Radicals ◽  
Kinetics Of ◽  
And Tungsten

The colorimetric method of estimating the rate of addition of hydrogen atoms to the oxides of molybdenum and tungsten is discussed in detail. It is also shown that alkyl radicals are efficiently removed by molybdenum oxide, and allowance is made for the effect of their presence on the blueing rate of the oxide surface. The method of evaluating collision efficiencies from the data obtained is indicated in full, and the construction and operation of a calculator to assist in the computation is described.

scholarly journals The kinetics of the interaction of atomic hydrogen with olefines IV. Results obtained by the foregoing techniques

1949 ◽  
Vol 196 (1047) ◽  
pp. 494-509 ◽  
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Atomic Hydrogen ◽  
Experimental Techniques ◽  
Effective Diameter ◽  
Collision Efficiency ◽  
Ethylene Propylene ◽  
Theoretical Considerations ◽  
Kinetics Of ◽  
Effect Of Structure

The experimental techniques and theoretical considerations developed in the previous parts have been utilized in obtaining data on the reactions of the type H + C n H 2 n = C n H 2 n +1 . The olefines used were ethylene, propylene, iso -butene, n -pentene-2 ( cis ), and 2, 3, 3, tri-methyl-butene-1. Certain tentative suggestions as to the effect of structure on the reactivity of the double bond are put forward, but in general, the collision efficiency of a hydrogen atom with an olefine lies between 10 –3 and 10 –4 . It is noted that in the computation of the collision efficiency, it seems to be rather unsatisfactory that the diameter of the whole molecule should be used and it is suggested that perhaps the effective diameter of a more intimate part of the molecule in the region of the double bond should be employed.

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.

Photolyse du butène-1 dans l'ultraviolet à vide

1973 ◽  
Vol 51 (17) ◽  
pp. 2853-2859 ◽  
Author(s):  
Guy J. Collin
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Kinetic Energy ◽  
Thermal Energy ◽  
Hydrogen Atoms ◽  
Excited Molecules

The vacuum u.v. photolysis of 1 -butene was studied in the 147–105 nm region. The main products formed from the fragmentation of excited molecules are allene, 1,3-and 1,2-butadienes, ethylene, and acetylene. The addition of a hydrogen atom to the double bond produces mainly secondary butyl radicals (91%) at 147 nm. At 123.6 nm, this proportion becomes 82%. Thus at shorter wavelengths (10 and 11.6–11.8 eV), hydrogen atoms are produced with a kinetic energy higher than the thermal energy.

The reaction of hydrogen atoms with ethylene

1970 ◽  
Vol 316 (1527) ◽  
pp. 575-591 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Rate Constant ◽  
Recombination Reaction ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Hydrogen Atoms ◽  
Ethyl Radical ◽  
Cracking Reaction ◽  
Computer Calculations ◽  
First Time

A detailed study has been made of the products from the reaction between hydrogen atoms and ethylene in a discharge-flow system at 290 ± 3 K. Total pressures in the range 8 to 16 Torr (1100 to 2200 Nm -2 ) of argon were used and the hydrogen atom and ethylene flow rates were in the ranges 5 to 10 and 0 to 20 μ mol s -1 , respectively. In agreement with previous work, the main products are methane and ethane ( ~ 95%) together with small amounts of propane and n -butane, measurements of which are reported for the first time. A detailed mechanism leading to formation of all the products is proposed. It is shown that the predominant source of ethane is the recombination of two methyl radicals, the rate of recombination of a hydrogen atom with an ethyl radical being negligible in comparison with the alternative, cracking reaction which produces two methyl radicals. A set of rate constants for the elementary steps in this mechanism has been derived with the aid of computer calculations, which gives an excellent fit with the experimental results. In this set, the values of the rate constant for the addition of a hydrogen atom to ethylene are at the low end of the range of previously measured values but are shown to lead to a more reasonable value for the rate constant of the cracking reaction of a hydrogen atom with an ethyl radical. It is shown that the recombination reaction of a hydrogen atom with a methyl radical, the source of methane, is close to its third-order region.

The reaction of alkyl radicals with metal oxides I. The reactions of ethyl radicals with molybdenum trioxide

1956 ◽  
Vol 236 (1207) ◽  
pp. 446-453
Keyword(s):  
Hydrogen Atom ◽  
Metal Oxides ◽  
Diethyl Ether ◽  
Ethyl Alcohol ◽  
Molybdenum Trioxide ◽  
Reaction System ◽  
Hydrogen Atoms ◽  
Alkyl Radicals ◽  
Products Of Reaction ◽  
Ethyl Radicals

It has been previously shown that molybdenum trioxide is a very efficient agent for removing hydrogen atoms and alkyl radicals from a reaction system. The nature of this removal process has been investigated for ethyl radicals produced by the addition of a hydrogen atom to ethylene. It is shown that the products of reaction with the oxide include ethyl alcohol and diethyl ether and the probable mode of formation of these two compounds is discussed.

Photolyse du méthyl-2-butène-1, du méthyl-3-butène-1 et du cis-pentène-2 à 174, 163 et 147 nm

1979 ◽  
Vol 57 (8) ◽  
pp. 863-869 ◽  
Author(s):  
Guy J. Collin ◽  
Hélène Deslauriers ◽  
Sylvain Auclair
Keyword(s):  
Double Bond ◽  
Photon Energy ◽  
Rate Constant ◽  
Pressure Effect ◽  
Low Pressure ◽  
Decomposition Process ◽  
Fragmentation Process ◽  
Quantum Yields ◽  
Methyl Radicals ◽  
Hydrogen Atoms

Photolysis of 2-methyl-1-butene (M2B1), cis-2-pentene (CP2), and 3-methyl-1-butene (M3B1) has been systematically studied at 163 nm. Pressure effect has been measured at 147, 163, and 174 nm. The main fragmentation process of the photoexcited olefine is the C—C split of the bond located in position β relative to the double bond:[Formula: see text] α-Methallyl radicals obtained in the M3B1 and CP2 photolysis decompose partly at low pressure, giving rise to the formation of 1,3-butadiene and hydrogen atoms. β-Methallyl radicals decompose also at low pressure into allene and methyl radicals. Butadiene and allene quantum yields follow the Stern–Volmer law, and this allows us to determine the ratio of the rate constant of dissociation relative to the rate constant of stabilization, kd/ks, through collision of the α- and β-methallyl radicals. From these values, we conclude that the excess of photon energy is not statistically distributed into the fragments, and that the decomposition process follows one (or several) particular law(s).

Initiation mechanisms in radical polymerizations : Reaction of cumyloxy radicals with methyl methacrylate and styrene

1982 ◽  
Vol 35 (10) ◽  
pp. 2013 ◽  
Author(s):  
E Rizzardo ◽  
AK Serelis ◽  
DH Solomon
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Methyl Methacrylate ◽  
Rate Constants ◽  
Polymer Structure ◽  
Hydrogen Atom Abstraction ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Constant Rate ◽  
Radical Generation

Cumyloxy (1-methyl-1-phenylethoxy) radicals have been generated by thermolysis (60�) of dicumyl hyponitrite in methyl methacrylate and styrene. The carbon-centred radicals formed by interaction of cumyloxyl with the respective monomers were trapped as stable adducts of 1,1,3,3-tetramethyl-isoindolin-2-yloxyl. Extensive hydrogen atom abstraction and methyl radical generation as well as double-bond addition were observed in methyl methacrylate. Styrene underwent only double-bond addition by both cumyloxy and methyl radicals. Some possible implications of these results for polymer structure are discussed. A kinetic study of the decomposition of dicumyl hyponitrite in cyclohexane at various temperatures gave k=7.7 × 1014exp(-13600/T) s-1 for the rate constant. Rate constants for the addition of cumyloxyl to methyl methacrylate (k ≈ 2 × 104 dm3 mol-1 s-1) and styrene (k≈2 × 105 dm3 mol-1 s-1) at 60�have been estimated.

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