For the S N 1 pathway, the activation energy is of the same order as for the S N 2 pathway in the absence of an electric field; the barrier of the rate-determining reaction step amounts to 37.7 kcal/mol. In the presence of an OEEF aligned with the dipole moment, however, no significant catalysis is observed. The reason for this limited effect is that now, the reaction axis associated with the second TS is orthogonal to the dipole moment (see Section S6 of Supporting Information). As such, the rate-determining TS is not stabilized significantly, whereas the reactant, i.e., the ribofuranosyl phosphate species, is.