THE SOLVENT EFFECT UPON THE AGGREGATION OF HYDROGEN-BONDED SYSTEMS WITH INTRAMOLECULAR PROTON-TRANSFER

The association of zwitterionic forms of o-methyl-aminophenols in solv ents of varying polarity (c between 2 and 32) was studied. It was foun d that the intramolecular proton transfer reaction plays a deciding ro le in this association. When the percentage of the ionic form is low ( less than 10 %) no association, even in nonpolar solvents, was observe d. In solvents of medium polarity the amount of ionic forms is suffici ently large to begin association but the solvent interaction with char ged groups is too weak to stabilize monomeric forms. In strongly polar solvents like alcohols the amount of ionic forms is large, but the sp ecific interaction with the solvent prevents any association.