A theoretical study of the proton affinities of water, alcohols, and ethers: absolute versus relative basicities

Abstract

In this work we report the proton affinities (E_pa) of water, seven alcohols, and seventeen cyclic and acyclic ethers, as measured by ion cyclotron resonance spectroscopy (ICR) with respect to the same ‘basicity ladder.’ The E_pa for selected compounds have been calculated by MNDO, AM1, and ab initio(3-21G and, in some cases, 4-31 G*//4-31 G and 6-31 G*//6-31 G) methods. These results are used for a comparison of the various computational techniques and for the analysis of structural effects on the neutral and protonated species. Methyl and other alkyl affinities of aliphatic alcohols are determined and discussed. The experimental E_pa are treated by correlation analysis methods.