Solute-solvent and solvent-solvent interactions in binary solvent mixtures. Part 8. The E-T(30) polarity of binary mixtures of formamides with hydroxylic solvents

Solvent effects on the binary mixtures of amides with alcohols and water we re investigated by means of Reichardt's E-T(30) solvatochromic indicator. E -T(N) parameters of binary solvent mixtures of formamide, N-methylformamide and N,N-dimethylformamide with water, methanol, propan-2-ol, 2-methylpropa n-2-ol, formamide, N-methylformamide and N,N-dimethylformamide were measure d over the whole composition range of the mixtures. Application of a prefer ential solvation model to the solvatochromic data shows that the preferenti al solvation of the solvatochromic indicator by the amides decreases in the order N-methylformamide > formamide > N,N-dimethylformamide. Synergism is observed for the mixtures of the amides with alcohols of similar polarity ( E-T(N) value), i.e. methanol-formamide, methanol-N-methylformamide, propan- 2-ol-N,N-dimethylformamide and 2-methylpropan-2-ol-N,N-dimethylformamide bi nary systems. Copyright (C) 1999 John Wiley & Sons, Ltd.