## Ritchie equation

https://doi.org/10.1351/goldbook.R05402
The @L03551@ $\log _{10}k_{\text{N}} = \log _{10}k_{0}+N_{\text{+}}$ applied to the reactions between nucleophiles and certain large and relatively @S05900@ organic cations, e.g. arenediazonium, triarylmethyl and aryltropylium cations in various solvents. $$k_{\text{N}}$$ is the @O04322@ for reaction of a given @C00907@ with a given nucleophilic system (i.e. given nucleophile in a given solvent). $$k_{0}$$ is the @O04322@ for the same @C00907@ with water in water, and $$N_{\text{+}}$$ is a parameter which is characteristic of the nucleophilic system and independent of the @C00907@. A surprising feature of the equation is the absence of a @C01124@ of $$N_{\text{+}}$$, characteristic of the substrate (cf. the $$s$$ in the @S06201@), even though values of $$N_{\text{+}}$$ vary over 13 log units. The equation thus involves a gigantic breakdown of the @R05186@. The equation has been extended both in form and in range of application.
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1161 [Terms] [Paper]