α-C-H bond dissociation energies of some tertiary amines

The alpha-C-H bond dissociation energies of 14 tertiary, trialkyl- and arylalkylamines have been measured by photoacoustic calorimetry (PAC). In general, the data lead to an upward revision of the bond dissociation energies (BDE's). The effects of alpha-phenyl and alpha-vinyl substitution have been quantified for the first time. alpha-Phenyl substitution was found to have a significantly smaller effect on lowering alpha-C-H BDE's than alpha-vinyl substitution. These data provide a thermochemical confirmation of the stereoelectronic hypothesis proposed by Lewis et al. in 1982.