Transition states, the stabilization

Tetrahedral intermediates, derived from carboxylic acids, spectroscopic detection and the investigation of their properties, 21, 37 Topochemical phenomena in solid-state chemistry, 15, 63 Transition state structure, crystallographic approaches to, 29, 87 Transition state structure, in solution, effective charge and, 27, 1 Transition state structure, secondary deuterium isotope effects and, 31, 143 Transition states, structure in solution, cross-interaction constants and, 27, 57 Transition states, the stabilization of by cyclodextrins and other catalysts, 29, 1 Transition states, theory revisited, 28, 139... 

Transition stale structure, secondary deuterium isotope effects and, 31, 143 Transition states, structure in solution, cross-interaction constants and, 27, 57 Transition states, the stabilization of by cyclodextrins and other catalysts, 29, 1 Transition states, theory revisited, 28, 139... 

Hammond s postulate can be applied to this series of the selectivity-determining steps of the radical chlorination shown in Figure 1.21. They all take place via early transition states, that is, via transition states that are similar to the starting materials. The more stable the resulting radical, the more similar to the starting materials is the transition state. The stability differences between these radicals are therefore manifested only to a very small extent as stability differences between the transition states that lead to them. All transition states are therefore very similar in energy, and thus... 

Another computationally fruitful way to think about these reactions is to first distort the addends to their transition state geometries, and to compare the energies of these isolated species with that of the transition state. Using the Salem-Hehre transition state, 64 kcal/mol is required to distort the isolated molecules to their transition state geometries, and uniting these distorted moieties causes a stabilization of 25 kcal/mol. Past the transition state, the stabilization energy increases faster than the destabilization. 

This would not mean that free radicals are actual intermediates, but only that the alkyl assumes a significant amount of radical character in the transition state. The stability of the radical type transition state may be increased by pairing between benzophenone ketyl radical and the alkyl radical [46],... 

Transition states, the stabilization of by cyclodextrins and other catalysts, 29, 1 Transition states, theory revisited, 28, 139... 

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