Enthalpies of dilution and enthalpies of mixing of α-amino acids + pyridine and α-amino acids + methylpyridine in aqueous solutions at 298.15 K

The enthalpies of mixing of aqueous solutions have been determined for glycine and l-alanine with pyridine and methylpyridine by flow microcalorimetry at 298.15 K. In addition, the enthalpies of dilution at 298.15 K of aqueous solutions containing glycine, l-alanine, pyridine, and methylpyridine have been obtained, respectively. These data have been analyzed using the McMillan−Mayer theory, and heterotactic interaction coefficients are given for the interaction of glycine and l-alanine with pyridine and methylpyridine, among which the enthalpic pairwise interaction coefficients, hxy, are discussed in terms of solute−solute interaction and substituent effects.