The effect of substituents on the deprotonation energy of selected primary, secondary and tertiary alcohols

Ab initio computations were carried out at the Hartree-Fock level of theory on primary, secondary and tertiary alcohols and also on their deprotonated conjugate bases containing methyl and phenyl substituents using a variety of basis sets (3-21G, 6-31G and triple-zeta) in combination with diffuse and polarization functions. The computed gas phase acidity as measured by the proton affinity of the conjugate bases (alkoxide ions) increased with increasing degree of substitution, in agreement with experimental gas phase acidity but in disagreement with experimental solution acidity trends. The molecular conformations, fundamental vibrational frequencies and charge distributions of selected alcohols and their conjugate bases were also studied. © 1995.