Thermochemistry of substituted pyridines and analogous heterocycles: the enthalpic increments for a group additivity scheme

Values available in the literature for the standard (p degrees = 0.1 MPa) m olar enthalpies of formation in the gaseous phases, at temperature 298.15 K , for substituted pyridines, such as methylpyridines, hydroxypyridines, ami nopyridines, cyanopyridines, chloropyridines and bromopyridines are reviewe d, discussed and interpreted in terms of contributions from atoms, bonds an d group of atoms as well as their interactions within the molecules. The en thalpic increments for each group contribution are calculated and suggested as parameters for a Group Additivity Scheme for the estimation of standard molar enthalpies of formation, in the gaseous state, of substituted pyridi nes. The validity of this approach is verified for different substituted py ridines. The scheme is tested with experimental values available for the st andard molar enthalpies of formation of substituted quinolines.