Organic Transition States

Abstract

The theoretical basis of Organic Chemistry lies in the understanding of organic reaction mechanisms. The reaction mechanism is generally a cursory description of the pathway followed by the different atoms in the molecule (or molecules) during the reaction. One important feature of the pathway is the actual geometry of the col, or potential barrier: the so-called transition state. Transition states are not amenable to direct experimental observation; only indirect gross information is available via experimental activation energies, entropies of activation, etc. Computation therefore seems an extremely appropriate tool for elucidating the structure of transition states. Of course the lack of available experimental data will be a drawback for any direct comparison; computation of the potential surface, to which we will restrict ourselves, would have to be followed by computation of dynamical trajectories before any meaningful comparison of rates, for instance, could be made. However the calculated transition state, and its energy relative to other competing points, can give information on the likely products to be obtained in the reaction.