Electrochemistry in media of intermediate acidity. VIII. Reversible oxidation products of the .alpha.-tocopherol model compound. Cation radical, cation, and dication

1974 ◽  
Vol 96 (8) ◽  
pp. 2409-2413 ◽  
Author(s):  
Ulla Svanholm ◽  
Klaus Bechgaard ◽  
Vernon D. Parker
Keyword(s):  
Radical Cation ◽  
Model Compound ◽  
Cation Radical ◽  
Alpha Tocopherol ◽  
Oxidation Products

Energies and Dipole Moments of Excited States of Ozone and Ozone Radical Cation Using Fock Space Multireference Coupled-Cluster Analytical Response Approach

2003 ◽  
Vol 68 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Devarajan Ajitha ◽  
Kimihiko Hirao ◽  
Sourav Pal
Keyword(s):  
Excited States ◽  
Radical Cation ◽  
Ground State ◽  
Fock Space ◽  
Dipole Moments ◽  
Cation Radical ◽  
Coupled Cluster ◽  
Complete Active Space ◽  
Triplet Excited States ◽  
Ground State Geometry

Using the Fock space multireference coupled-cluster (FS-MRCC) analytical linear response approach, we report the dipole moments of low-lying singlet and triplet excited states of ozone. The low-lying singlet and triplet excited states are calculated at the ground-state geometry and at the adiabatic geometry for the 1A2 and 1B1. For comparison we also calculate at the ground-state geometry the dipole moments of the 1A2, 1B1 and 1B2 using multireference configuration interaction (MRCI) with a bigger VQZ basis and complete active space. We also report as by-product the excitation energy values in the singles and doubles approximation. At the ground-state geometry we also report the energy and the dipole moments of the 2A1, 2A2 and 2B1 states of the ozone radical cation. The energy of the ozone cation radical is compared with the other correlated approaches. It matches well with the experimental values.

The effect of meta- and para-methoxy substitution on the reactivity of the radical cations of arylalkenes and alkanes. Radical ions in photochemistry. Part 26

1991 ◽  
Vol 69 (5) ◽  
pp. 839-852 ◽  
Author(s):  
Donald R. Arnold ◽  
Xinyao Du ◽  
Kerstin M. Henseleit
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Bond Cleavage ◽  
Cation Radical ◽  
Radical Cations ◽  
Addition Product ◽  
Molecular Orbital Calculations ◽  
Carbon Carbon Bond ◽  
Markovnikov Addition ◽  
Cis And Trans

The effect of meta- and para-methoxy substitution on the reactivity of some radical cations has been determined. The compounds chosen for study were 1-(3-methoxyphenyl)-1-phenylethylene (7), 1-(4-methoxyphenyl)-1-phenylethylene (8), 3-(3-methoxyphenyl)indene (9), 3-(4-methoxyphenyl)indene (10), methyl 2-(3-methoxyphenyl)-2-phenylethyl ether (11), methyl 2-(4-methoxyphenyl)-2-phenylethyl ether (12), cis- and trans-2-methoxy-1-(3-methoxyphenyl)indane (13), and cis- and trans-2-methoxy-1-(4-methoxyphenyl)indane (14). The radical cations of these compounds were generated by photosensitization (electron transfer) using 1,4-dicyanobenzene (3) as the electron acceptor. The three reactions studied were: (1) The addition of nucleophiles (methanol) to the radical cation of the arylalkenes, a reaction that yields the anti-Markovnikov addition product. (2) The carbon–carbon bond cleavage of radical cations, which yields products derived from the radical and carbocation fragments. (3) The deprotonation of the radical cation, a reaction that can be used to invert the configuration at a saturated carbon centre. The mechanisms of these reactions are discussed and the factors that need to be considered in order to predict reactivity are defined. Molecular orbital calculations (UHF/STO-3G) were carried out on the radical cations of the model compounds 3- and 4-vinylanisole and 3- and 4-methylanisole. Key words: photochemistry, photosensitize (electron transfer), radical cation, radical.

Reactions of aN-Acyliminium Ion Pool with Benzylsilanes. Implication of a Radical/Cation/Radical Cation Chain Mechanism Involving Oxidative C−Si Bond Cleavage

2007 ◽  
Vol 129 (7) ◽  
pp. 1902-1903 ◽  
Author(s):  
Tomokazu Maruyama ◽  
Yusuke Mizuno ◽  
Ikuo Shimizu ◽  
Seiji Suga ◽  
Jun-ichi Yoshida
Keyword(s):  
Radical Cation ◽  
Bond Cleavage ◽  
Cation Radical ◽  
Chain Mechanism

Oxidations of vitamin E (.alpha.-tocopherol) and its model compound. 2,2,5,7,8-Pentamethyl-6-hydroxychroman. A new dimer

1988 ◽  
Vol 53 (6) ◽  
pp. 1281-1284 ◽  
Author(s):  
Cacang Suarna ◽  
Donald C. Craig ◽  
Keith J. Cross ◽  
Peter T. Southwell-Keely
Keyword(s):  
Vitamin E ◽  
Model Compound ◽  
Alpha Tocopherol

scholarly journals Antioxidant activity: what do we measure?

1999 ◽  
Vol 46 (1) ◽  
pp. 23-29 ◽  
Author(s):  
G Bartosz ◽  
M Bartosz
Keyword(s):  
Antioxidant Activity ◽  
Sulfonic Acid ◽  
Cation Radical ◽  
Oxidation Products ◽  
Maximal Rate ◽  
Rapid Reduction ◽  
Main Effect ◽  
Before And After ◽  
Lag Period ◽  
Similar Decrease

Inhibition of oxidation of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) by free radicals generated by decomposition of 2,2'-azobis(2-amidopropane) (ABAP) by antioxidants and biological material was studied. A correlation was found between the ability of various substances to delay the onset of ABTS oxidation and their rapid reduction of the ABTS+* cation radical, and between the ability to reduce the maximal rate of ABTS oxidation and slow reduction of ABTS+*. The length of the lag period of ABTS oxidation was found to be independent of ABTS concentration. Similar decrease of peroxynitrite-induced ABTS+* formation by antioxidants was observed when the antioxidants were added before and after peroxynitrite. All these findings indicate that the main effect of antioxidants in this system is reduction of ABTS+* and not prevention of its formation. Reduction of oxidation products rather than inhibition of their formation may be the predominant mode of action of antioxidants in various assays of antioxidant activity.

Reactions of the melatonin metabolite N1-acetyl-5-methoxykynuramine (AMK) with the ABTS cation radical: identification of new oxidation products

Redox Report ◽  
2006 ◽  
Vol 11 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Ni Ni Than ◽  
Christina Heer ◽  
Hartmut Laatsch ◽  
Rüdiger Hardeland
Keyword(s):  
Cation Radical ◽  
Oxidation Products
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