Calculations for para-substituted phenols using the CNDO/2 method

The character and degree of influence of the substituting groups X in the para position to the hydroxyl groups of phenol were studied in [I] using experimental data on IR, PMR, and UV spectra, the increase in the interaction moment, etc. It is interesting to compare the results obtained in this case with measurements of the electron density in the atoms and the calculated orbital energies. The semiempirical SCF MO LCAO method was used in the CNDO/2 approximation [2] to calculate the charges on the atoms and the energies of the orbitals for molecules having the composition p-XC6H~OH (X= H, F, CI, CHa, OCHa, OH, NH2, CHO, and NO2). The data on the molecular structure were taken from Sutton's tables [3]. In those cases when a different position was possible for the X with respect to the OH, the calculation was made for two configurations with a cis and trans position. The calculated values of the dipole moments, energy of the molecule (Etot) , upper occupied (Euo) and lower vacant (ELv) orbitals and also the charges on the atoms are given in Tables i and 2.