Amine basicities in benzene and in water
Abstract
The constants for ion-pair formation with 2,4-dinitrophenol in benzene (KB), and the pKa, values in water, of thirty-three amines have been measured. According to the class of amine, two different situations can be observed: for primary amines and secondary cyclic amines, the effects of structural variations on basicity are higher in water than in benzene; on the other hand, for tertiary amines these effects are similar in the two solvents. KB, Values of primary amines give a good correlation with σ*. The Taft and Hancock equation allows a unifying treatment of KB, values of the various classes of amines.