Réduction catalytique de cétones α,β-éthyléniques à température modérée par

1979 ◽  
Vol 57 (2) ◽  
pp. 218-221 ◽  
Author(s):  
D. Beaupere ◽  
P. Bauer ◽  
R. Uzan
Keyword(s):  
Electrochemical Reduction ◽  
Reduction Potential ◽  
Initial Rate ◽  
Substituent Effects ◽  
Hydrogenation Reaction ◽  
Unsaturated Ketones ◽  
Hydride Ion ◽  
Inverse Effect ◽  
Electron Donating Groups

The use of the catalyst [Formula: see text] in the reduction of the ethylenic system of styryl ketones by 1-phenylethanol permits the hydrogenation reaction to proceed at 50 °C. Some substituent effects in the α,β-unsaturated ketones were demonstrated at this temperature. These showed an increase in the initial rate of reduction for electron-attracting groups and the inverse effect for electron-donating groups. The observation of a relation between the electrochemical reduction potential of these ketones and their rate of hydrogenation suggests a transfer of hydrogen to the ketone by a hydride ion intermediate. [Journal translation]

Kinetics and mechanism of oxidation of N,N′-dimethyl-9,9′-biacridanyl by some π acceptors and a one-electron oxidant

1985 ◽  
Vol 63 (2) ◽  
pp. 445-451 ◽  
Author(s):  
Allan K. Colter ◽  
Charles C. Lai ◽  
A. Gregg Parsons ◽  
N. Bruce Ramsey ◽  
Gunzi Saito
Keyword(s):  
Electron Transfer ◽  
Reduction Potential ◽  
Isotope Effects ◽  
Substituent Effects ◽  
Kinetic Isotope Effects ◽  
Spin Trapping ◽  
Single Electron Transfer ◽  
Kinetic Isotope ◽  
The One ◽  
Rule Out

Oxidation of N,N′-dimethyl-9,9′-biacridanyl (DD) has been investigated as a model for single electron transfer (SET)-initiated oxidation of NADH coenzyme models such as N-methylacridan (DH). Oxidants investigated cover a 1010-fold range of reactivity in acetonitrile and include the π acceptors 1,4-benzoquinone (BQ), 2,6-dichloro-1,4-benzoquinone (DCIBQ), p-chloranil (CA), 2,3-dicyanobenzoquinone (DCBQ), 2,3-dicyano-1,4-naphthoquinone (DCNQ), 2,3-dicyano-5-nitro-1,4-naphthoquinone (DCNNQ), 9-dicyanomethylene-2,4,7-trinitrofluorene (DCMTNF), 9-dicyanomethylene-2,4,5,7-tetranitrofluorene (DCMTENF), 7,7,8,8-tetracyanoquinodimethane (TCNQ), and tetracyanoethylene (TCNE), and the one-electron oxidant tris(2,2′-bipyridyl)cobalt(III), [Formula: see text] The oxidation product is, in every case, N-methylacridinium ion (D+). A mechanism involving a rate-determining electron transfer with simultaneous fragmentation to D+ and N-methyl-9-acridanyl radical (D•) is proposed. This mechanism is supported by the observed dependence of the rate on oxidant reduction potential, by spin-trapping experiments, by kinetic isotope effects in oxidation of 9,9′-dideuterio-DD, and by substituent effects in oxidation of 2,2′- and 3,3′-dimethoxy-DD. The rate of oxidation of DD relative to that of DH is 3.4 × 102 with [Formula: see text] and with the π acceptors varies from ea. 0.3 (BQ) to 8.1 × 104 (DCMTENF). The results rule out a SET-initiated mechanism for oxidation of DH by all of the oxidants studied except TCNQ and DCMTENF.

Pt(iv) analogs of oxaliplatin that do not follow the expected correlation between electrochemical reduction potential and rate of reduction by ascorbate

2012 ◽  
Vol 48 (6) ◽  
pp. 847-849 ◽  
Author(s):  
Jenny Z. Zhang ◽  
Ezequiel Wexselblatt ◽  
Trevor W. Hambley ◽  
Dan Gibson
Keyword(s):  
Electrochemical Reduction ◽  
Reduction Potential

Substituent effects on electroreduction of the carbon-halogen bond

1981 ◽  
Vol 34 (11) ◽  
pp. 2331 ◽  
Author(s):  
RS Abeywickrema ◽  
EW Della
Keyword(s):  
Reduction Potential ◽  
Halogen Bond ◽  
Substituent Effects ◽  
High Yield ◽  
Polarographic Reduction ◽  
Electric Field Effects ◽  
Controlled Potential Electrolysis ◽  
Half Wave ◽  
Controlled Potential ◽  
Substituted 1

Polarographic reduction of a series of 4-substituted 1-iodobicyclo[2,2,2]octanes has been examined in an attempt to assess the effect of substituents on the half-wave reduction potential. It is found that the values of E� do not show a linear correlation with the relevant σ1 constants; the deviations are discussed in terms of the relative importance of the steric and electric field effects of the substituent. Controlled-potential electrolysis of a number of the substrates reveals that the hydrocarbon corresponding to fission of the carbon-iodine bond is formed in high yield.

Substituent effects on fluorescence properties of thiazolo[4,5-b]pyrazine derivatives

2014 ◽  
Vol 13 (12) ◽  
pp. 1765-1772 ◽  
Author(s):  
Tatsuki Nakagawa ◽  
Minoru Yamaji ◽  
Shojiro Maki ◽  
Haruki Niwa ◽  
Takashi Hirano
Keyword(s):  
Substituent Effects ◽  
Phenyl Group ◽  
Fluorescence Yield ◽  
Fluorescence Properties ◽  
Electron Donating Groups ◽  
Phenyl Moiety

A study of fluorescence properties of thiazolo[4,5-b]pyrazine derivatives with the phenyl group at C2, prepared from amidopyrazines. The introduction of electron-donating groups onto the 2-phenyl moiety increases the fluorescence yield and appearance of solvatochromic character.

Reduction properties of nitrated naphthalenes: Relationship between electrochemical reduction potential and the enzymatic reduction by microsomes or cytosol from rat liver

1992 ◽  
Vol 85 (2-3) ◽  
pp. 187-197 ◽  
Author(s):  
Nobuhisa Iwata ◽  
Kiyoshi Fukuhara ◽  
Kazuhiro Suzuki ◽  
Naoki Miyata ◽  
Atsushi Takahashi
Keyword(s):  
Electrochemical Reduction ◽  
Rat Liver ◽  
Reduction Potential ◽  
Enzymatic Reduction

Syntheses and photochemical properties of octasubstituted phthalocyaninato zinc complexes

2001 ◽  
Vol 05 (11) ◽  
pp. 782-792 ◽  
Author(s):  
SUZANNE E. MAREE ◽  
TEBELLO NYOKONG
Keyword(s):  
Thin Layer ◽  
Singlet Oxygen ◽  
Electrochemical Reduction ◽  
Zinc Complexes ◽  
Quantum Yields ◽  
Photochemical Properties ◽  
High Concentrations ◽  
Electron Donating Groups ◽  
Selection Of

In this work a selection of octasubstituted phthalocyaninato zinc complexes were synthesized and their photochemistry studied. The substituents included cholesterol (3a), estrone (3b), naphthol (3c) and phenoxy groups substituted with CH3 (3d), C ( CH 3)3 (at two positions, 3e), C ( CH 3)3 (3f), NO2 (3g), NH 2 (3h), COH (3i), COOH (3j), and H (3k). In general, complexes containing electron-donating groups attached to the phenoxy ring (e.g. 3e and 3f) were found to be photochemically unstable with photobleaching quantum yields of the order of 10-3. In the presence of electron-withdrawing groups (3g, 3i, and 3j) the photobleaching quantum yields were of the order of 10-6 to 10-5. Singlet oxygen quantum yields (ΦΔ) ranged from 0.01 to 0.73. The lowest ΦΔ was observed for the highly aggregated complex 3c. All the complexes showed aggregation at high concentrations. Electrochemical reduction using a thin-layer spectroelectrochemistry cell showed that the complexes become more monomeric following reduction.

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