HYDROGEN-BONDING .39. THE PARTITION OF SOLUTES BETWEEN WATER AND VARIOUS ALCOHOLS

The general solvation equation log SP = c + rR(2) + s pi(2)(H) + a Sig ma a(2)(H) + b Sigma beta(2)(H) + nu V-x was applied to the partition of solutes between water and isobutanol, pentanol, hexanol, octanol, d ecanol and oleyl alcohol. It is shown that the two main factors that i nfluence partitioning are solute hydrogen-bond basicity Sigma beta(2)( H) and solute volume V-x. The b coefficient becomes steadily more nega tive along the above series of alcohols, showing that the alcoholic ph ases, which are all less acidic than water, become less and less acidi c as the chain length increases, and the water content of the alcoholi c phase decreases, The nu coefficient, on the other hand, becomes grad ually more positive, indicating that as the chain length increases and the water content decreases, the alcoholic phase becomes more and mor e hydrophobic, Of great significance is that for all six alcohols, the a coeffcient is effectively zero, so that all alcoholic phases have t he same basicity as bulk water, no matter what their water content is, It is suggested that, contrary to results of solvatochromic measureme nts, the alcohols have similar hydrogen-bond basicity to water.