N.M.R. shift and diffusion study of aqueous mixtures of formamide, N-methylformamide and N,N-dimethylformamide

Abstract

A nuclear magnetic resonance investigation has been carried out on aqueous mixtures of formamide, N-methylformamide, and N,N-dimethylformamide over the entire concentration range. In the three systems the existence of extensive solvent interactions was indicated by the marked concentration dependence of the proton resonance shifts of all components. From the observed concentration dependence of the amide proton shifts, information concerning the nature of the interactions occurring in the pure components and in aqueous solution was gained. Self-diffusion coefficients of the nonaqueous components of N-methyl- and N,N-dimethylformamide-D₂O mixtures were measured by the nuclear magnetic resonance spin echo techniques. Here, also, the data gave information concerning the associative processes occurring in the pure amide and in aqueous mixtures.