Enthalpies of transfer of some non-electrolytes from acetonitrile to acetonitrile–methanol mixtures

The enthalpies of transfer of water, propan-1-ol, 2-methylpropan-2-ol, octan-1-ol, formamide, N-methyl-formamide, N,N-dimethylformamide, dimethyl sulphoxide and propylene carbonate from acetonitrile to methanol and acetonitrile–methanol mixtures are reported and analysed in terms of solvation theory. The analyses show that all of the solutes, except propylene carbonate, interact more strongly with methanol than acetonitrile, and are preferentially solvated by methanol in the mixed solvents. It is also found that the extent to which the solutes disrupt solvent–solvent bonding is greatest for the amides and dimethyl sulphoxide, which act only as hydrogen-bond acceptors, and is relatively insensitive to the size of the alkyl groups on the alcohols.