THE DETECTION OF FREE RADICALS IN HYDROGEN ATOM REACTIONS WITH ORGANIC MOLECULES

1948 ◽  
Vol 26b (3) ◽  
pp. 343-355 ◽  
Author(s):  
G. M. Harris ◽  
A. W. Tickner
Keyword(s):  
Free Radical ◽  
Hydrogen Atom ◽  
Specific Activity ◽  
Reaction System ◽  
Radical Mechanism ◽  
Hydrogen Atoms ◽  
Experimental Conditions ◽  
Alkyl Radicals ◽  
Free Radical Mechanism ◽  
Positive Results

The Paneth–Rice free radical detection technique has been applied to the study of reactions of hydrogen atoms, produced by the discharge tube method, with two compounds, acetone and dimethyl mercury. Bismuth has been demonstrated to be a satisfactorily stable 'mirror metal' for the purpose, although some evidence was noted for the formation of a short-lived hydride of this metal under the adopted experimental conditions. A method has been devised for the preparation of radioactive bismuth mirrors of known specific activity, utilizing Bi210 ('Radium E'), obtained from uranium extraction residues, as the tracer. The hydrogen atom – acetone reaction system gave no evidence in the present work for the formerly postulated existence of free alkyl radicals. However, conclusive positive results were obtained in the case of the dimethyl mercury reaction. Studies in which the methane–ethane ratio in the products of the latter reaction was compared in presence and absence of the radical-sensitive mirror have further supported a previously proposed free radical mechanism.

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.

THE DECOMPOSITION OF METHANE BY LOW-ENERGY ELECTRONS

1960 ◽  
Vol 38 (6) ◽  
pp. 858-868 ◽  
Author(s):  
J. E. Manton ◽  
A. W. Tickner
Keyword(s):  
Free Radical ◽  
Major Part ◽  
Low Energy ◽  
Radical Mechanism ◽  
Experimental Conditions ◽  
Free Radical Mechanism ◽  
Low Energy Electrons ◽  
Decomposition Of Methane ◽  
Higher Hydrocarbons

The decomposition of methane by a beam of electrons having energies between 15 and 100 ev has been studied using methane pressures between 10−2and 10−3 mm of mercury. The products were frozen out on a surface cooled to about −220 °C and situated approximately 5 millimeters from the electron beam.Ethane, ethylene, and acetylene were found to be the main products along with smaller amounts of saturated and unsaturated higher hydrocarbons. The results provide some evidence that under these experimental conditions ions do not play a major part in the decomposition and a free radical mechanism has been proposed to explain the formation of the main products.

THE REACTION OF 2-CYANO-2-PROPYL FREE RADICALS WITH OXYGEN: 2-CYANO-2-PROPYL HYDROPEROXIDE

1960 ◽  
Vol 38 (7) ◽  
pp. 1154-1157 ◽  
Author(s):  
M. Talât-Erben ◽  
Nevzat Önol
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Hydrogen Cyanide ◽  
Elevated Temperatures ◽  
Radical Mechanism ◽  
Acetone Cyanohydrin ◽  
Experimental Conditions ◽  
Polymerization Catalyst ◽  
Free Radical Mechanism ◽  
Induced Decomposition

The reaction with oxygen of cyanisopropyl free radicals generated by the polymerization catalyst 2,2′-azobisisobutyronitrile has been investigated. In xylene, or benzene, as solvent at 55° the products identified are: (1) a new compound, 2-cyano-2-propyl hydroperoxide; (2) acetone cyanohydrin; (3) hydrogen cyanide; (4) cyanogen; (5) acetone; (6) p-methyl benzaldehyde (in xylene only); and (7) tetramethylsuccinodinitrile. The hydroperoxide is surprisingly stable; its physical constants are: b.p. 37 °C at 1 mm Hg; m.p. −9 to −8°; [Formula: see text] 1.4138; d20 1.013 g/ml. In benzene under the same experimental conditions, only a very small amount of the hydroperoxide is obtained, the principal product being acetone cyanohydrin. A free-radical mechanism is proposed. The induced decomposition of the hydroperoxide, which is important in benzene, is almost completely inhibited in the presence of xylene. The new hydroperoxide can be used as a polymerization catalyst at moderately elevated temperatures.

Comparative QSAR evidence for a free-radical mechanism of phenol-induced toxicity

2000 ◽  
Vol 127 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Corwin Hansch ◽  
Susan C. McKarns ◽  
Carr J. Smith ◽  
David J. Doolittle
Keyword(s):  
Free Radical ◽  
Radical Mechanism ◽  
Free Radical Mechanism

Dirhodium(II)-Catalyzed Diamination Reaction via a Free Radical Pathway

2021 ◽  
Author(s):  
Zhiying Fan ◽  
Zhifan Wang ◽  
Ruoyi Shi ◽  
Yuanhua Wang
Keyword(s):  
Free Radical ◽  
Bond Formation ◽  
Mechanistic Study ◽  
Radical Mechanism ◽  
Free Radical Mechanism

Unlike C-N bond formation with classical dirhodium(II)-nitrenoids as the key intermediate, dirhodium(II)-catalyzed 1,2-and 1,3-diamination reactions are realized by a free radical mechanism. A mechanistic study revealed that the reactions undergo...

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