UC San Diego

1:1 Equilibrium constants, K, for the association of hydrogen bond bases and hydrogen bond acids have been determined using solvent octan-1-ol at 298 K for 30 acid-base combinations. The values of K are much smaller than those found for aprotic, rather non-polar solvents. It is shown that the log K values can satisfactorily be correlated against a^H ₂*b^H ₂, where a^H ₂ and b^H ₂are the 1:1 hydrogen bond acidities and basicities of solutes. The slope of the plot, 2.938, is much smaller than those for log K values in the non-polar organic solvents previously studied. An analysis of literature data on 1:1 hydrogen bonding in water yields a negative slope for a plot of log K against a^H ₂*b^H ₂, thus showing how the use of very strong hydrogen bond acids and bases                                                 does not lead to larger values of log K for 1:1 hydrogen bonding in water. It is suggested that for simple 1:1 association between mono-functional solutes in water, log K cannot be larger than about -0.1 log units. Descriptors have been obtained for the complex between 2,2,2-trifluoroethanol and propanone, and used to analyze solvent effects on the two reactants, the complex, and the complexation constant.