Enthalpic discrimination of position isomerism: Pairwise interaction of piperidinecarboxylic acid isomers in DMSOÂ +Â H2O mixtures at 298.15Â K

► Isothermal titration calorimetry can differentiate positional isomers. ► When w < 0.10 the values of hXX vary according to the sequence: meta > para > ortho. ► When w > 0.15 the values of hXX vary according to the sequence: para > meta > ortho.► Hydrophobic-hydrophilic interactions can be deduced by the sign and magnitude of hXX.