https://doi.org/10.1351/goldbook.08185
Rate constants for the reactions of \(\ce{sp^{2}{-}hybridized}\) electrophiles with nucleophiles can be expressed by the correlation \[\lg [k/(\pu{dm3 mol-1 s-1})] = s_{\rm{N}}(E + N)\] where \(E\) is the nucleophile-independent electrophilicity parameter, \(N\) is the electrophile-independent nucleophilicity parameter, and \(s_{\rm{N}}\) is the electrophile-independent nucleophile-specific susceptibility parameter.
Notes:
- This equation is equivalent to the conventional linear Gibbs energy relationship \(\lg k = Nu + s_{\rm{N}}E\), where \(Nu = s_{\rm{N}}N\). The use of \(N\) is preferred, because it provides an approximate ranking of relative reactivities of nucleophiles.
- The correlation should not be applied to reactions with bulky electrophiles, where steric effects cannot be neglected. Because of the way of parametrization, the correlation is applicable only if one or both reaction centers are carbon.
- As the \(E\) parameters of the reference electrophiles are defined as solvent-independent, all solvent effects are shifted into the parameters \(N\) and \(s_{\rm{N}}\).
- The equation transforms into the Ritchie equation for \(s_{\rm{N}} = 1\).
- Applications to \(\rm{S}_{\rm{N}}2\mbox{-}type\) reactions are possible if an electrophile-specific susceptibility parameter is introduced.
- The Mayr scale is available at https://www.cup.lmu.de/oc/mayr/DBintro.html.