3 edition of Substituent Effects in Radical Chemistry (NATO Science Series C:) found in the catalog.
September 30, 1986
Written in English
|Contributions||Heinz G. Viehe (Editor), Zdenek Janousek (Editor), Robert Merényi (Editor)|
|The Physical Object|
|Number of Pages||500|
Substituent Effects on the C C Bond Strength, – Geminal Substituent Effects, – Stabilization of the Cyano(dimethylamino)methyl Radical – Synergistic effect Due to Interaction Between α‐Amino and α‐Cyano Groups on the Radical Stabilization Energy†. The effects of substituents in the meta and para positions of the benzyl radical on the α-hydrogen hyperfine coupling constants (hfc's) are discussed. The electron spin resonance (esr) spectra of the para-methyl, ethyl, isopropyl, and tert-butyl substituted benzyl and cumyl radicals are onjugation involving the C—C bond is 40–60% as effective as C—H Cited by:
These deviations are attributed to merostabilization of the radical-like species, and an empirical approach designed to evaluate the importance of this effect is developed. Ab initio calculations of molecular orbital energies in meta - and para -substituted benzaldehydes are used to evaluate the substituent effects on E 1/2 red and E T n,π Cited by: The substituent effect is one of the most important concepts in chemistry, biochemistry, and related fields. In this chapter, we collected the works devoted to this issue in relation to.
Mechanisms are not only presented in the traditional contexts of rate laws and substituent effects but, whenever possible, are illustrated using practical, useful and state-of-the-art reactions. The abundance of stereoselective reactions included in the treatise makes the reader familiar with key concepts of . Rate effects also are produced by different substituents, as is evident from the data in Table for basic hydrolysis of some substituted ethyl benzoates. A nitro substituent increases the rate, whereas methyl and methoxy substituents decrease the rate relative to that of the unsubstituted ester.
Overmans exhibition and school dialogues ...
Annual authorization of the Panama Canal Commission and the annual authorization for the United States Maritime Administration
An introduction to the Old Testament in Greek
Dying to sin
High-temperature superconductivity in perspective.
Kosmos, the eternal ebb and flow of matter and force
First Arab Science Congress
Connected Mathematics Looking for Pythagoras
Horizons of anthropology
Teacher education for aesthetic education
Substituent Effects in Radical Chemistry Editors: Viehe, Heinz G., Janousek, Zdenek, Merényi, Robert (Eds.). Studies on the Captodative Effect.
Entropy/Enthalpy Compensation as Solvent Effect in Radical Forming Reactions. Substituent Effects on the Oxidation of Toluenes by Molecular Oxygen: The Surprising Reactivity of p.
Free Radical Additions of Dichloromethane to δ-Alkenyl T-Butyl Peroxides. A Theoretical Approach to Substituent Effects in radical Chemistry.- 2. Sigma and Pi Effects in Radicals.- 3.
The Contrasting Strain Energies of Small Ring Carbon and Silicon Rings. The Relationship with Free Radical Energies.- 4. Allylic and Allenic Capto-dative Stabilization in Nitrogen Centered Free Radicals. A Theoretical Approach to Substituent Effects in radical Chemistry Sigma and Pi Effects in Radicals The Contrasting Strain Energies of Small Ring Carbon and Silicon Rings.
The Relationship with Free Radical Energies Allylic and Allenic Capto-dative Stabilization in Nitrogen Centered Free Radicals.
Understanding the role of substituents is of great importance for the preparation of novel phenolic compounds with enhanced antioxidative properties. In this work, the antioxidative activity of isoflavonoid derivatives with different substituents placed at the C2 position was determined by density functional theory (DFT) calculations.
The bond dissociation enthalpy (BDE), ionization potential Cited by: 3. In this paper we make a survey of various aspects of radical chemistry to which we have made some contribution. Our Localized Molecular Orbital (LMO) approach to the electronic structure and react vity of chemical species allowed us to generalize the Linnett theory and to describe the mechanism of various processes involving free by: Substituent Effects in the Vinylcyclopropane Radical Cation Rearrangement: A Computational Road to a New Synthetic Tool Jonas Oxgaard Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN ‐, USA, Cited by: 7.
Spectroscopy, Substituent Effects, and Reaction Mechanisms. Abstract. Applications of density functional theory (DFT) calculations to organic chemistry are shown, beginning with geometry optimization and the calculation of vibrational frequencies, Author: Burkhard Kirste.
affect the chemistry and properties of another part of the same molecule. Substituent Effects (A) When the part of the molecule that we vary is a discrete atom or molecular fragment, we call it a substituent.
Substituent effects are the changes on a reaction or property in the unchanged part of the molecule resulting from substituent Size: 60KB. These effects are a combination of RESONANCE and INDUCTIVE effects (see next page) The effects are also important in other reactions and properties (e.g.
acidity of the substituted benzoic acids).Here are some general pointers for recognising the substituent effects. The H atom is the standard and is regarded as having no effect.; Activating groups increase the rate. Tetrahedron Letters No, pp.Pergamon Press. Printed in Great Britaih.
SUBSTITUENT EFFECTS AND FREE RADICAL STABILITY. THE METHOXY GROUP Jack W. Timberlake and Melvin L, Hodges Department of Chemistry, Louisiana State University in New Orleans New Orleans, Louisiana (Received in USA 4 September ; received in 13K for publication Cited by: Transient free radicals are formed during photolysis of the 1-(2-nitrophenyl)ethyl ester of adenosine triphosphate (caged ATP).
Journal of Photochemistry and Photobiology A: Chemistry(1), DOI: /S(98)Cited by: The electronic effect of the substituent is mainly composed of two parts: the field/inductive effect (represented by parameter F) and the resonance effect (characterized by parameter R) [13,23,24].
In this work, the electronic effects of the substituents on the reaction enthalpies have also by: 3. Several 6-chromanol derivatives with various substituents (one or two amino, acetylamino, chloro or nitro substituents at the 5- 7- 8- or 5,7-positions on the phenyl ring of 2,2-dimethylchromanol) were synthesized, and their second order rate constants (k) for a reaction that demonstrates radical scavenging activity (reaction with the galvinoxyl radical) were by: 1.
In organic chemistry and biochemistry, a substituent is an atom or group of atoms which replaces one or more hydrogen atoms on the parent chain of a hydrocarbon, becoming a moiety of the resultant new molecule.
The terms substituent and functional group, as well as other ones (e.g. These substituent radical scales measure the component of energy attributed to the spin delocalisation in the benzyl radical.
For para substituents there is however an insufficient range of data available and as a result it was concluded, that problems related to the relative magnitude and even the direction of the substituent effects on benzyl Cited by: Substituent Effects (A) When the part of the molecule that we vary is a discrete atom or molecular fragment, we call it a substituent.
Substituent effects are the changes on a reaction or property in the unchanged part of the molecule resulting from substituent variation.
Some Reactions or Properties. The substituent effect on the 5-(π-exo)exo cyclization has been estimated by the relative rate constants, k R, calculated for several substituents in the 4- and 3-position. Results show that stabilization and polar factors slightly affect the rate of the vinyl radical cyclization onto arene rings, which appears to be rather unselective with respect to the nature of the by: / Hg ‘satellite’ features have been resolved in electron paramagnetic resonance (EPR) spectra recorded from radical cations of diphenylmercury and its bis-ortho-allyloxy derivatives as isolated in solid freon matrices at 77 accord with our previous work, we confirm that the parent radical cation of diphenylmercury is a σ-species with substantial electron loss from the C–Hg.
European Journal of Organic Chemistry VolumeIssue Full Paper. Structural Effects in Radical Clocks and Mechanisms of Grignard Reagent Formation: Special Effect of a Phenyl Substituent in a Radical Clock when the Crossroads of Selectivity is at a Metal/Solution Interface.
Hassan Hazimeh. Université Paul Cézanne, iSm2, UMR CNRS Cited by: 4. In this paper the reaction enthalpies of three antioxidant action mechanisms, HAT, SET–PT, and SPLET, for mono-substituted Stobadines were calculated in gas-phase and water.
Results show that elect Cited by: Substituents at C-1 or C-5 of the pentadienyl radical also have a significant effect on the regioselectivity of the conjugated diene hydroperoxides formed, larger substituents directing oxygen addition to the pentadienyl radical at the site of least steric by: Indeed the topic chosen seems to be quintessential for the whole radical chemistry understanding and exploiting (single and multiple) substituent effects on radicals.
We had the honour to organise this Workshop because some years ago, in collaboration with L. Stella, we became involved in radical stabi lising effects when both a donor and an acceptor (captor) groups are present on a C-radical.