Pair-wise interactions by gas chromatography. VII. Interaction free enthalpies of solutes with secondary alcohol groups

A polar type liquid having a secondary alcohol substituent on a branched alkane skeleton, SOH, was used as stationary phase. The molecules of this stationary phase are nearly isomorphous and isochor with those of the branched alkane, C78, elected as standard, i.e., the molecules of both solvents have nearly the same form and the same size. Partition properties of 158 chosen molecular probes were measured by gas chromatography on SOH and on an SOH-C78 mixture having a volume fraction of thetaOH = 0.5. Based on the resulting data an interaction free enthalpy could be calculated, i.e., the additional effect of the secondary alcohol to partition. Comparison with data determined earlier on another member of this solvent family, POH, having a primary alcohol as interacting group gives information about the effect of steric hindrance on polar type solute-solvent interaction free energies.