Free-Radical Reductions of Arenediazonium Ions in Aqueous Solution. VI. On Iododediazoniation

1985 ◽  
Vol 38 (6) ◽  
pp. 991 ◽  
Author(s):  
JE Packer ◽  
RER Taylor
Keyword(s):  
Aqueous Solution ◽  
Free Radical ◽  
Aqueous Solutions ◽  
Major Product ◽  
Chain Reaction ◽  
Γ Irradiation ◽  
A Chain

γ-Irradiation of aqueous solutions of p-ClC6H4N2+BF4- and KI initiates a chain reaction in which dichloroazobenzene is the major product. When iodine is also present the chain reaction is longer and the major product is chloroiodobenzene . The reaction � ������������������������� I2-·+ArN2+ → I2+Ar·+N2 is suggested to be propagation step in both reactions, with Ar · reacting with I3- in the presence of iodine and with ArN2+ in its absence. The relevance of these reactions to iododediazoniation is discussed.

Radiation-induced Rearrangement of Ethylene Glycol in Aqueous Solution

1971 ◽  
Vol 49 (14) ◽  
pp. 2382-2389 ◽  
Author(s):  
C. E. Burchill ◽  
K. M. Perron
Keyword(s):  
Hydrogen Peroxide ◽  
Ethylene Glycol ◽  
Aqueous Solutions ◽  
Transfer Reaction ◽  
Major Product ◽  
Hydrogen Atom Transfer ◽  
Γ Irradiation ◽  
Radical Chain ◽  
Radiation Induced ◽  
A Chain

Under γ-irradiation, aqueous solutions of ethylene glycol containing hydrogen peroxide form acetaldehyde as a major product via a free-radical chain rearrangement. The yield of acetaldehyde is essentially unchanged when hydrogen peroxide is replaced by N2O or HClO4. A mechanism is proposed in which the glycol radical, ĊOHCH2OH, rearranges to the acetaldehyde precursor, ĊH2CHO, followed by the hydrogen atom transfer reaction;[Formula: see text]thus propagating a chain reaction.2The rearrangement is also induced by the photo-dissociation of H2O2 in aqueous solutions of ethylene glycol.

Studies of radiation-induced reactions of ethylene in aqueous solution II. Reactions in the presence of oxygen as studied by pulse radiolysis and γ -irradiation techniques

1967 ◽  
Vol 300 (1463) ◽  
pp. 443-454 ◽  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Rate Constants ◽  
Pulse Radiolysis ◽  
Major Product ◽  
Peroxy Radicals ◽  
Ferrous Ions ◽  
Constant Composition ◽  
Γ Irradiation ◽  
Radiation Induced

The radiolysis of dilute aqueous solutions containing ethylene and oxygen has been investigated. Pulse radiolysis was used to measure the rate constants for the addition of hydroxyl radicals to ethylene, the binary decomposition of the resulting hydroxyethyl radicals and their addition to ethylene and reaction with oxygen to yield peroxy radicals. The rate constants have also been determined for the mutual interaction of the peroxy radicals and their reaction with ferrous ions. The principal products of γ -irradiation were aldehydes and organic hydroperoxides. Hydrogen peroxide was found in yields close to the molecular yield from water. The polymer produced in the absence of oxygen was not formed, and glycollaldehyde, reported as a major product by previous workers, could not be detected. At constant composition of the gas mixtures, product yields were unaffected by total pressure in the range up to 40 atm, but were strongly dependent on the proportion of oxygen. Aldehyde yields were markedly greater at pH 1.2 than in neutral solution. The influence of ferrous ions an d of added hydrogen peroxide has been determined. The pulse radiolysis and γ -irradiation experiments complement one another and show that the radiation-induced oxidation of ethylene in aqueous solution involves the same primary reactions as occur in the absence of oxygen, followed by the formation and further reactions of peroxy radicals.

Absolute rate constants for hydrocarbon autoxidation. 33. A product study of the self-reaction of α-tetralylperoxyls in solution

1983 ◽  
Vol 61 (9) ◽  
pp. 2037-2043 ◽  
Author(s):  
A. Baignée ◽  
J. H. B. Chenier ◽  
J. A. Howard
Keyword(s):  
Steady State ◽  
Free Radical ◽  
Rate Constant ◽  
Rate Constants ◽  
The Self ◽  
Absolute Rate ◽  
Chain Reaction ◽  
Low Concentrations ◽  
A Chain ◽  
Product Study

The major initial products of the self-reaction of α-tetralylperoxyls (C10H11O2•) in chlorobenzene at 303–353 K are equal concentrations of α-tetralol and α-tetralone in ~90% yield based on the number of initiating radicals. These yields are consistent with the non-radical (Russell) mechanism for self-reaction. Low concentrations of bis(α-tetralyl) peroxide are produced, indicating that there is a small but detectable free-radical contribution towards termination. C10H11O2• undergoes β-scission in this temperature range but steady-state concentrations of C10H11• are too low to influence the termination rate constant 2kt, or react with C10H11O2• to give (C10H11O2. α-Tetralol to α-tetralone ratios and total yields of these products are significantly less than 1 and 100%, respectively, in methanol and acetonitrile. Formaldehyde is produced in methanol indicating the involvement of α-hydroxymethylperoxyls, derived from the solvent, in termination. There is no evidence for a chain reaction or a zwitterion intermediate for self-reaction of C10H11O2• in solution.

Radiation-induced oxidation of 2-propanol by hydrogen peroxide in aqueous solutions

1970 ◽  
Vol 48 (8) ◽  
pp. 1232-1238 ◽  
Author(s):  
C. E. Burchill ◽  
I. S. Ginns
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Aqueous Solutions ◽  
Lower Limit ◽  
Alcohol Concentration ◽  
Chain Mechanism ◽  
Radiation Induced ◽  
A Chain ◽  
High Yields ◽  
Radical Conversion

The radiation-induced oxidation of 2-propanol by hydrogen peroxide in neutral deaerated aqueous solution has been investigated. 2-Propanol is oxidized to acetone, and hydrogen peroxide reduced in stoichiometrically equivalent high yields. The yields are independent of hydrogen peroxide concentration in the range 5 × 10−2 to 10−3 M and linearly dependent on alcohol concentration in the range 0.13 to 1.05 M. The reaction yields increased with decreasing dose rate.The results are explained by a chain mechanism in which initiation occurs via H-atom abstraction from 2-propanol to form either (CH3)2ĊOH (1) or CH3 CHOH ĊH2 (2). 1 reacts with H2O2 in a chain propagating reaction[Formula: see text]2 may abstract the α hydrogen from the parent alcohol[Formula: see text]or undergo bimolecular termination. A lower limit of 53 ± 101mole−1 s−1 is estimated for the rate constant for this radical conversion reaction.

Radical-Induced Oxidation of Dithiothreitol in Acidic Oxygenated Aqueous Solution:  A Chain Reaction

1997 ◽  
Vol 119 (24) ◽  
pp. 5735-5739 ◽  
Author(s):  
Manohar Lal ◽  
Raghavendra Rao ◽  
Xingwang Fang ◽  
Heinz-Peter Schuchmann ◽  
Clemens von Sonntag
Keyword(s):  
Aqueous Solution ◽  
Chain Reaction ◽  
A Chain

Homogeneous Polymerization of Butadiene Catalyzed by Rhodium Salts

1967 ◽  
Vol 40 (2) ◽  
pp. 602-613
Author(s):  
C. E. H. Bawn ◽  
D. G. T. Cooper ◽  
A. M. North
Keyword(s):  
Free Radical ◽  
Active Species ◽  
Solution Polymerization ◽  
Chain Reaction ◽  
Hydride Shift ◽  
Ligand Displacement ◽  
A Chain ◽  
Organic Amines ◽  
Homogeneous Polymerization ◽  
Protonic Acids

Abstract A study has been made of the solution polymerization of butadiene, to predominantly trans 1, 4 polymer, catalysed by rhodium salts. The reaction is accelerated by protonic acids (including water) and by those reducing agents which in aqueous systems would be capable of reducing RhIII to RhI. Ligands such as organic amines, and also bromide and iodide anions, tend to retard or even inhibit the reaction. The overall process appears to be a chain reaction, but is not free radical in character. The mechanism which best fits all the observations is one in which the active species is a π-allylic rhodium hydride, initiation occurring by hydride shift and propagation occurring by a ligand displacement process.

O2.cntdot.- Addition to ketomalonate leads to decarboxylation: a chain reaction in oxygenated aqueous solution

1991 ◽  
Vol 113 (18) ◽  
pp. 6934-6937 ◽  
Author(s):  
Man Nien Schuchmann ◽  
Heinz Peter Schuchmann ◽  
Martina Hess ◽  
Clemens Von Sonntag
Keyword(s):  
Aqueous Solution ◽  
Chain Reaction ◽  
A Chain
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