https://doi.org/10.1351/goldbook.H02732
The equation in the form: log10(kk0)=ρ σ or log10(KK0)=ρ σ applied to the influence of meta- or para-substituents X on the reactivity of the
functional group
Y in the benzene derivative m- or p-XC6H4Y. k or K is the rate or
equilibrium constant
, respectively, for the given reaction of m- or p-XC6H4Y; k0 or K0 refers to the reaction of C6H5Y, i.e. X = H; is the substituent constant characteristic of m- or p-X: is the reaction constant characteristic of the given reaction of Y. The equation is often encountered in a form with log10k0 or log10K0 written as a separate term on the right hand side, e.g. log10k=ρ σ+log10k0 or log10K=ρ σ+log10K0 It then signifies the intercept corresponding to X = H in a regression of log10k or log10K on σ.
See also:
ρ-value
,
σ-constant
,
Taft equation
,
Yukawa–Tsuno equation
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1119 [Terms] [Paper]