The cis–trans isomerization of the radical anion of biacetyl

1976 ◽  
Vol 54 (23) ◽  
pp. 3637-3640 ◽  
Author(s):  
A. John Elliot ◽  
Jeffrey K. S. Wan
Keyword(s):  
Radical Anion ◽  
Esr Spectroscopy ◽  
Solvent Composition ◽  
Trans Isomers ◽  
Trans Isomerization

The equilibrium between the cis and the trans isomers of the biacetyl radical anion has been studied by esr spectroscopy. The dependence of this equilibrium on the solvent composition and temperature was followed.

Association of radical anion with alkali cations. IV. ESR study of the 4-nitrobenzophenone radical anion

1980 ◽  
Vol 45 (2) ◽  
pp. 369-375 ◽  
Author(s):  
Stanislav Miertuš ◽  
Ondrej Kyseľ
Keyword(s):  
Hyperfine Splitting ◽  
Radical Anion ◽  
Esr Spectroscopy ◽  
Supporting Electrolyte ◽  
Esr Spectra ◽  
Proton Donor ◽  
Alkali Cations

The 4-nitrobenzophenone radical anion prepared by electrolysis was studied by ESR spectroscopy. On the basis of the interpretation of ESR spectra, the conformation of this system was estimated. The effect of the concentration of supporting electrolyte and of the presence of a proton-donor agent (C2H5OH) was examined. It is assumed that changes in hyperfine splitting constants are caused by association.

Stability of radical anions derived from substituted 5-nitrofurans investigated by ESR spectroscopy

1985 ◽  
Vol 50 (7) ◽  
pp. 1594-1601 ◽  
Author(s):  
Jiří Klíma ◽  
Larisa Baumane ◽  
Janis Stradinš ◽  
Jiří Volke ◽  
Romualds Gavars
Keyword(s):  
Radical Anion ◽  
High Stability ◽  
Esr Spectroscopy ◽  
Reaction Path ◽  
Order Reaction ◽  
Second Order ◽  
Radical Anions ◽  
Second Order Reaction ◽  
Unpaired Electron Density ◽  
The Stability

It has been found that the decay in dimethylformamide and dimethylformamide-water mixtures of radical anions in five of the investigated 5-nitrofurans is governed by a second-order reaction. Only the decay of the radical anion generated from 5-nitro-2-furfural III may be described by an equation including parallel first- and second-order reactions; this behaviour is evidently caused by the relatively high stability of the corresponding dianion, this being an intermediate in the reaction path. The presence of a larger conjugated system in the substituent in position 2 results in a decrease of the unpaired electron density in the nitro group and, consequently, an increase in the stability of the corresponding radical anions.

ChemInform Abstract: A Study by ESR Spectroscopy of the Di-tert-butylsilanone Radical Anion

ChemInform ◽  
2010 ◽  
Vol 23 (50) ◽  
pp. no-no
Author(s):  
A. G. DAVIES ◽  
A. G. NEVILLE
Keyword(s):  
Radical Anion ◽  
Esr Spectroscopy

Competing Radical- and Anion-Mediated Pathways in the Reduction of Bridgehead Tosylates with Lithium Aluminium Hydride

1999 ◽  
Vol 52 (5) ◽  
pp. 367 ◽  
Author(s):  
Ernest W. Della ◽  
Wit K. Janowski
Keyword(s):  
Electron Transfer ◽  
Ring Opening ◽  
Radical Anion ◽  
Lithium Aluminium Hydride ◽  
Trans Isomers ◽  
Lithium Aluminium ◽  
Mechanism Of Reaction ◽  
Anion Transfer

Reaction of norborn-1-yl tosylate with lithium aluminium hydride in boiling tetrahydrofuran affords a mixture of norbornan-1-ol accompanied by the ring-opened products 4-methylcyclohexanol and 3-ethylcyclopentanol as their cis/trans isomers, as well as p-thiocresol and p-tolyl disulfide. Evidence strongly suggests that the reaction is mediated by the norborn-1-yloxy radical rather than the norborn-1-yloxy anion. The process is initiated by very slow acyl oxygen fission of the norbornyl tosylate, followed by reduction of the derived p-toluenesulfinate ion to give the p-thiocresoxide anion. Transfer of an electron from the latter to the substrate and decomposition of the derived norborn-1-yl tosylate radical anion leads to the norborn-1-yloxy radical which, upon ring opening, generates the monocyclic alcohols via the corresponding ketones. It is noteworthy that, when norborn-1-yl mesylate is exposed to lithium aluminium hydride, it yields norbornan-1-ol exclusively. In the absence of an efficient electron-transfer agent, the mechanism of reaction of norborn-1-yl mesylate is suggested to involve acyl oxygen fission only.

Cis-Trans Isomerization in Natural Polyisoprenes

1960 ◽  
Vol 33 (2) ◽  
pp. 445-456 ◽  
Author(s):  
J. I. Cunneen
Keyword(s):  
Sulfur Dioxide ◽  
Natural Rubber ◽  
Ultraviolet Light ◽  
Low Temperatures ◽  
Structural Changes ◽  
Trans Isomers ◽  
Gutta Percha ◽  
Trans Isomerization ◽  
Cis And Trans Isomers ◽  
Cis And Trans

Abstract The cis and trans isomers of many simple olefins and conjugated polyolefins can be interconverted by the action of heat, light, and various catalysts, and in many such systems the changes in geometric configuration can be readily followed and the isomers separated and identified. Previous attempts to isomerize natural rubber and gutta-percha by treatment with ultraviolet light and various chemicals gave no detectable cis-trans isomerization, and in general configurational changes in unconjugated polyolefins have been unknown until recently when Golub converted the cis-1,4 units in polybutadiene into the corresponding trans units. This isomerization was achieved by irradiation of the cis-polymer with ultraviolet light in the presence of various organic bromides and sulfur compounds, but apparently this method did not isomerize natural rubber. In attempts to retard the rate of crystallization of natural rubber at moderately low temperatures—i.e., −10° to −40° C—by the attachment of side groups which would interfere with the molecular packing, it was observed that very small amounts of thiol acids were remarkably effective. This suggested that structural changes other than simply the attachment of side groups were occurring in the polyisoprene molecule. Recently it was found that thiol acids could interconvert the cis and trans forms of a simple trialkyl ethylene—e.g., 3-methylpent-2-ene—and subsequently, the isomerization of natural rubber and gutta-percha by these reagents was also observed. Following this, natural rubber, gutta-percha, squalene and cis and trans forms of 3-methylpent-2-ene have also been isomerized by treatment with sulfur dioxide and allied compounds; this work, including an investigation of the physical properties of the vulcanizates obtained from some of the isomerized polyisoprenes, is described in the present paper.

Structural features of 1,3,5-trifluorobenzene radical anion, as studied by optically detected ESR spectroscopy and quantum chemistry

2013 ◽  
Vol 62 (11) ◽  
pp. 2311-2316 ◽  
Author(s):  
S. V. Blinkova ◽  
M. M. Vyushkova ◽  
L. N. Shchegoleva ◽  
I. V. Beregovaya ◽  
V. A. Bagryansky ◽  
...  
Keyword(s):  
Quantum Chemistry ◽  
Radical Anion ◽  
Esr Spectroscopy ◽  
Structural Features ◽  
Optically Detected

scholarly journals Thermal Cis to Trans Isomerization of [PtCl2(C2H5CN)2] and Crystal Structures of the cis- and trans-Isomers.

1995 ◽  
Vol 49 ◽  
pp. 72-75 ◽  
Author(s):  
Per Svensson ◽  
Karin Lövqvist ◽  
Vadim Yu. Kukushkin ◽  
Åke Oskarsson ◽  
Michael P. Hartshorn ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Trans Isomers ◽  
Trans Isomerization ◽  
Cis And Trans Isomers ◽  
Cis And Trans
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