Molecular association of N,N-dimethylacetamide in carbon tetrachloride as an inert medium and its water mixtures

Abstract

The molecular association in N,N-dimethylacetamide (DMAc or DMA) and DMAc/H₂O mixtures was investigated using FT-IR spectroscopy. The density functional theory (DFT) calculations and spectral deconvolution identified the primary molecular association types among DMAc molecules, and the position of the characteristic peaks. Using two-dimensional infrared correlation analysis, the transition processes among several molecular association types were investigated as functions of temperature and concentration, the Trimer type of N,N-dimethylacetamide is the main association compared to the other associations (Free, Dimer and higher molecular aggregates (Agg)). In DMAc/H₂O mixtures, we observed that water interacts with the carbonyl group through hydrogen bonding, and the evolution of dominant cluster structures in the system was examined as a function of DMAc concentration.