Hydrogen-Bonded Species of Pyridinium Halogenoacetetes. 2. Thermometric Behavior in Aprotic Solvents

Article abstract of DOI:10.1021/j150656a044

The enthalpies of reaction of a series of substituted pyridines and of triethylamine, quinoline, and isoquinoline (for the sake of comparison) with trifluoroacetic acid (TFA) in chloroform were measured at 25 deg C at final solution concentrations ranging from 1E-2 to 5E-2 M.The enthalpies of reaction of 2,4,6-trimethylpyridine, pyridine, and 4-cyanopyridine with trichloroacetic acid (TCA), dichloroacetic acid (DCA), monochloroacetic acid (MCA), and acetic acid (AcOH) in chloroform were also measured at 25 deg C.The concentration dependence of enthalpies of reaction was examined by measuring them for 2,4,6-trimethylpyridine-TFA, pyridine-TFA, and 4-cyanopyridine-TFA in chloroform over the entire possible solution concentration range at 25 deg C.In order to study the energetic behavior of H-bonded species of the ptridine-TFA system in media of different dielectric constants, the enthalpy measurements were made in p-dioxane, o-xylene, and carbon tetrachloride.The thermometric results have been discussed in terms of interactions present in the H-bonded species of these systems in nonaqueous solutions.