POLARITY, HYDROGEN-BONDING, AND STRUCTURE OF MIXTURES OF WATER AND CYANOMETHANE

The polarity of mixtures of water and cyanomethane was established from measurements of Kamlet and Taft's (KT's) pi-*, their hydrogen bond acceptance ability from measurements of KT's-beta, and their hydrogen bond donation ability from measurements of KT's-alpha, with suitable solvatochromic indicators. The structure of these mixtures was explored by use of thermodynamic data from the literature and the application of the quasi-lattice quasi-chemical (QLQC) and the inverse Kirkwood-Buff integral (IKBI) methods. It is concluded that these methods point toward strong so-called microheterogeneity in these mixtures, i.e., preference for neighbors of the same kind, that extends over several concentric shells around a given molecule. This preference decreases with increasing temperatures. The polarity and hydrogen bonding ability results are explained in terms of these structural features of the mixtures.