Substituent Effects in Radical Chemistry

Respectably old radical chemistry which plays a rna jor role in life-processes, both desired (breathing, ... ) and non-desired (in flammatory diseases, ageing, ... ) has been gaining new youth in the past decade. Modern spectroscopy and other physical methods, recent advances in computational methods as well as impressive and mechanistically well-understood syntheses have led to a number of spectacular deve lopments in the field of radical chemistry. The impact of these achi evements will reach far beyond the field of organic chemistry, for example into biology and medicine. New facts and concepts in this rapidly expanding field deserved discussion among a number of leading experts present at the Workshop both for the information and constructive criticism. This happened during a particular brainstorming session and some of the impressions and reflections exchanged are recorded in the Epilogue. 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. This leads to an enhanced stabilisation which we called the captodative effect and we have endeavoured the first extensi ve investigation of this effect on carbon centered radicals.

Sommario

1. 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.- 5. Conformational Preferences in Beta Substituted Ethyl Radicals A Quantitative Analysis of Hyperconjugation, Homoconjugation, d-Orbital and Steric Effects.- 6. Substituent Effects on the Thermochemistry and Electrochemistry of Free Radicals.- 7. Some Applications of ES? Spectroscopy to the Study of Substituent Effects.- 8. Substituent Effects on Absolute Rate Constants and Arrhenius Parameters for the Addition of tert-Butyl Radicals to Alkenes.- 9. Allylic Radicals-An ESR Spectroscopical Study.- 10. ESR-Spectroscopical Investigation of Capto-dative Substituent Effects in Benzyl Radicals.- 11. The Effect of Substituents on Benzylic Radical ESR Hyperfine Coupling Constants. The ?? Scale Based Upon Spin Delocalization.- 12. Determination of Thermodynamic Stabilisation in Amino-Substituted Alkyl radicals.- 13. Phosphinylhydrazyls R2 NNP(O)L2. Influence of the Phosphinyl Group on the 3-Electron NN Pi Bond.- 14. Substituent Effects on the Dimerization of Vinyl Nitroxides and on the Dissociation of Their Tricyclic Dimers.- 15. Substituent Effects on the CC-Bond Strength.- 16. The Different Recombinations of Diphenyl Methyl Radicals Ph2 C°-R, R = tBu, CN, COOR', COR'.- 17. Some Chemistry of Radical Ions.- 18. Substituent Effects on the Methylenecyclopropane Rearrangement. A Probe for Free Radical Effects.- 19. 2-Oxomorpholin-3-yl Radicals.- 20. Azoalkane Decompositions as Measures of Radical Substituent Effects.- 21. Orbital Effects in CarbohydrateRadicals.- 22. ESR-Spectroscopical Investigation of Carbohydrate Radicals in Solution. Radical Stabilization by Beta C-0 Bonds.- 23. Studies on the Captodative' Effect. Entropy/Enthalpy Compensation as Solvent Effect in Radical Forming Reactions. A relative Radical Stabilisation Scale.- 24. ?° Revisited.- 25. Captodative Effect on the relative Rates of H-Abstraction by Tert-Butoxy Radicals.- 26. Substituent Effects in Gas-Phase Thermal Hydroxylation and Hydrogenolysis.- 27. Heterocyclic Substituents in SRNl Reactions.- 28. Substituent Effects on the Oxidation of Toluenes by Molecular Oxygen: The Surprising Reactivity of p-Methoxytoluene.- 29. Free Radical Additions of Dichloromethahe to ?-Alkenyl t-Butyl Peroxides.- 30. The Non-Chain Radicaloid Mechanism of Some Nucleophilic Substitution Reactions.- 31. Captodative Substituent Effects in Cycloaddition Reactions.- 32. Captodative Substitution Effect in [2+2] Cycloadditions Between Alienes and Olefins.- 33. Captodative Alkenes as Dipolarophiles-Kinetic Studies.- 34. Captodative Alkenes in Concerted 1, 3-Dipolar Cycloadditions.- 35. Photo-Diels-Alder Addition of Two Captodative Alkenes to 1-Acetonaphtone.- 36. Free Radical Cyclization of Unsaturated Carbonic acid Derivatives.- 37. Synthetic Applications of the Polar Effects of the Substituents in Free-Radical Reactions.- 38. Selectivity in Homolytic Aromatic Substitutions. Alkylations of Pyridines.- 39. The Invention of High-Yielding Radical Chain Reactions.- 40. Epilogue.- Participants.

Relazione

`This book as a top level scientific kaleidoscope is recommended to all organic chemists and related researchers who wish to know and apply the results of the modern radical chemistry. Anyone who would like to participate in the exciting further development of this area should read this book from cover to cover.'
Reaction Kinetics and Catalysis Letters, Vol. 34, No. 2, 1987

Dettagli sul prodotto

• Con la collaborazione di: Zdene Janousek (Editore), Zdenek Janousek (Editore), Robert Merenyi (Editore), Robert Merényi (Editore), Heinz G. Viehe (Editore)
• Editore: Springer Netherlands
• Lingue: Inglese
• Formato: Tascabile
• Pubblicazione: 18.10.2013
• EAN: 9789401086141
• ISBN: 978-94-0-108614-1
• Pagine: 482
• Illustrazioni: XIV, 482 p.
• Serie: NATO Science Series C: (Closed; Nato Science Series C: NATO Science Series C:
• Categoria: Scienze naturali, medicina, informatica, tecnica > Chimica > Chimica organica