On Polarizability Effect of Alkyl Substituent

The relative polarizability effect of alkyl substituent can be conveniently obtained by calculating the so-called Polarizability Effect Index (PEI) value, proposed firstly in our laboratories, PEI = Σ (a i /N i 2 ), where a i is the polarizability of primary units CH3, CH 2 -, CH C-, and the N i is the carbon atom number from reaction site to the primary unit. By using the PEl and atomic charge in a molecule, the ionization potential of alkyl halide, the enthalpy of reaction for the gas-phase addition of a proton to an alcohol or ether (proton affinity), the gas-phase basicity of alcohols or ethers (proton affinity), and gas-phase acidity of alcohols can be quantitatively modeled by the two-parameter expression equation.