Radicals atomization energy

TABLE 12.3. Radical Atomization and Reorganizational Energies (kcal/mol)... 

Free radicals Atoms or groups of atoms with unpaired electrons and which are therefore highly reactive. They can be produced by high-energy radiation such as ultraviolet light in photochemical reactions. 

Brocks JJ, Beckhaus H-D, Beckwith ALJ, Ruchardt C (1998) Estimation of bond dissociation energies and radical stabilization energies by ESR spectroscopy. J Org Chem 63 1935-1943 Buxton GV, Langan JR, Lindsay Smith JR (1986) Aromatic hydroxylation. 8. A radiation chemical study of the oxidation of hydroxycyclohexadienyl radicals. J Phys Chem 90 6309-6313 Buxton GV, GreenstockCL, Helman WP, Ross AB (1988) Critical review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals ( OH/O -) in aqueous solution. J Phys Chem Ref Data 17 513-886... 

Calculations approaching HF accuracy showed that BNC should be more stable than BCN, BCC more stable than CBC, and BCB more stable than BBC.424 Combined with estimates of the correlation energy, the atomization energy of BNC was predicted to be 0.48 hartree, in good agreement with experiment. The ground-state X22+ configuration of BCC is consistent with the results of e.s.r. measurements, which show BCC to be a o-radical. 

Radical stabilization energies for a wide variety of carbon-centered radicals have been calculated at G3(MP2)-RAD or better level. While the interpretation of these values as the result of substituent effects on radical stability is not without problems, the use of these values in rationalizing radical reactions is straight forward. This is not only true for reactions involving hydrogen atom transfer steps but also for other reactions involving typical elementary reactions such as the addition to alkene double bonds and thiocarbonyl compounds. 

National Centre for Free Radical Research housing a 7-MeV LINAC facility on the Pune University campus with support from the Department of Atomic Energy. He has published nearly 100 papers and co-edited a book on Radiation Chemistry Present Status and Future Trends in 2001. 

Molecules, free radicals, atoms, and, indeed, ions, may possess excess energy by virtue of excitation in electronic, vibrational, rotational or translational modes where such exist. A number of reactions are known in which such energy-rich species participate. Much interest lies in the fundamental problem of how the excess energy carried by a reactant can overcome the energy barrier to reaction. 

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