The transfer of neutral molecules, ions and ionic species from water to benzonitrile; comparison with nitrobenzene

Equations have been constructed for the transfer of 64 neutral solutes from water and from the gas phase to the solvent benzonitrile. The equations contain five descriptors and can be used to predict further values of the water–benzonitrile and gas–benzonitrile partition coefficients for a wide range of solutes. The water–benzonitrile equation has been extended to include ions and ionic species derived from acids by loss of a proton and bases by acceptance of a proton. Only two further descriptors are needed, one for anions and one for cations. A previous equation for transfer of neutral solutes from water to nitrobenzene has also been extended to include ions and ionic species. Comparison of the equations for transfer to benzonitrile and to nitrobenzene shows that the two solvents behave quite similarly, although benzonitrile as a solvent is a stronger hydrogen bond base.

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► An equation for water–benzonitrile partition of neutral molecules and ions is derived.
► The factors that influence partition are explained.
► A comparison is made with partition into nitrobenzene.
► Hydrogen bonding is important for partitions into both solvents.