An investigation of the possibility of alternating electrostatic potentials in substituted alkanes

Our aim in this work has been to determine whether the calculated electrostatic potentials of a group of fluoro, chloro, and hydroxy derivatives of ethane and propane reflect the alternation of electronic charge buildup that has earlier been proposed to occur in such molecules. The electrostatic potentials were obtained with ab initio SCF molecular wave functions that were computed in terms of basis sets of various sizes. The atomic charges calculated from these wave functions do show some degree of alternation; however, none whatsoever has been found in the electrostatic potentials. These two observations are not necessarily inconsistent, since electrostatic potentials and electronic densities do not always vary in the same manner. However, since electrostatic potentials have been shown to be effective indicators of the reactive sites on molecules, especially toward electrophilic attack, it appears that the alternation of charge buildup - if such a phenomenon does indeed occur - does not produce a corresponding alternation in reactive sites.