pKaHC
pKaHC is a term used in physical organic chemistry to denote the pKa value associated with the deprotonation of a carbon–hydrogen bond in hydrocarbons. It reflects the acidity of hydrocarbons as Brønsted acids, where removal of a proton from a C–H bond yields a carbanion. Because many C–H bonds are highly nonpolar and stabilized only modestly as anions, pKaHC values are among the largest typically tabulated acidities.
The concept is highly solvent-dependent and bond-specific. In aqueous solution, C–H bonds display a broad range
In practice, pKaHC values are used to compare relative acidity of different C–H bonds and to assess
See also: pKa, carbanion, Brønsted acidity, C–H bond activation, solvent effects on acidity.