A THEORETICAL-STUDY OF THE PROTON AFFINITIES OF WATER, ALCOHOLS, AND ETHERS - ABSOLUTE VERSUS RELATIVE BASICITIES

In this work we report the proton affinities (Epa) 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 Epa for selected compounds have been calculated by MNDO, AM1, and ab initio (3-21G and, in some cases, 4-31G*//4-31G and 6-31G*//6-31G) 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 Epa are treated by correlation analysis methods.