Heats of Reaction of Resonance-Stabilized Carbenium Ions with Nitrogen Bases

Article abstract of DOI:10.1021/jo00008a031

Heats of reaction (ΔH_rxn) are reported for five resonance-stabilized carbenium ions with ten aliphatic amines and seven pyridines in sulfolane at 25 deg C to produce substituted ammonium ions.Heats of reaction (ΔH_rxn) for these neutral bases fall in the same range as the corresponding heats of reaction of the carbenium ions with a variety of resonance-stabilized anions (carbanions, and oxyanions) whose pK_as are comparable to those of the amines and pyridines.Although the ΔH_rxns do not correlate with the aqueous pK_BH(1+)s of the amines, good correlations are obtained using the pK_R(1+)s of the carbenium ions and with th e gas-phase heats of reaction of the amines with trimethylboron.Also, the ΔH_rxns of pyridines with the carbenium ions correlate fairly well with the pK_R(1+)s of the carbenium ions and are surprisingly insensitive to steric hindrance.