EFFECT OF THE SOLVENT ON THE EQUILIBRIA OF ACID-BASE INDICATORS IN APROTIC AND AMPHIPROTIC SOLVENTS

The dissociation constants of a series of indicators in N,N-dimethylformamide medium have been determined, and compared with those for the indicators in other aprotic solvents (dimethylsulphoxide and acetonitrile) and in some amphiprotic solvents (water, methanol, ethanol, propan-2-ol and tertbutanol). The effect of the solvent characteristics on the pK values have been evaluated, and the pK + p-gamma(w --> s)t(H+) values shown to be linearly correlated with the Dimroth and Reichardt E(T)N and acceptor number solvatochromic parameters.