Energy barriers
In a subsequent step we have computed both the structures and energies
of the transition states for the formation of the adducts in the
solvents. Table 4 gives the relative Gibbs free energy for the
transition structures computed for the direct reaction (in this case the
values are computed relative to the reagents) and for the reverse
reaction (in this case the values are computed relative to the adducts).
The existence of a barrier for the direct reaction is highly dependent
on the solvent. Solvents with higher dielectric constant, water in this
case, may induce an activation barrier.
Table 4. Gibbs free energy activation barrier to the direct and
reverse reactions (in kcal mol-1).