NMR study of hydrogen bonding in methanol – carbon tetrachloride solutions

The nuclear magnetic resonance (NMR) frequencies of the hydroxyl protons of methanol clusters in carbon tetrachloride were measured as a function of concentration between 245.4 and 320.2 K. The size of the methanol cluster (n) and the enthalpy and entropy of methanol self-association were obtained from nonlinear least-squares fittings to a model that assumed that only one dominant cluster was in equilibrium with the monomer at each temperature. The chemical shift measurements at 273 and 299.1 K fit best to theoretical curves calculated for a monomer–tetramer equilibrium. However, at higher and lower temperatures, the analyses indicate that the most dominant clusters are smaller and larger, respectively.Key words: alcohol liquid solutions, structure, hydrogen bonding, thermodynamics of self-association, nuclear magnetic resonance.