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 “C at final solution concentrations ranging from 1 X to 5 X lo-'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 ...