ELECTRONIC-STRUCTURE OF POLYCHLOROPHENOLS AND THEIR CARBOCATIONS

Polychlorophenols (PCP) with different numbers of chlorine atoms and t heir protonated forms have been calculated by the AM1 method with full optimization of geometry. The proton affinity of PCP with various typ es of coordination of the proton to the molecule has been estimated. T he calculations show that the proton affinity averaged over isomers de creases monotonically as the number of chlorine atoms increases. Based on the calculations of the carbocations, the sigma(+) constant of the OH-substituent at the ipso-position is equal to 0.69. There is fair a greement between the relative energies of the isomers of the carbocati ons determined from the constants of the substituents and calculated b y the AMI method. These energies can be recommended for qualitative es timation of the proton affinity in definite positions of aromatic mole cules with Cl- and OH-substituents.