## Wikipedia - Ecuación de Hammett (es) Wikipedia - Equació de Hammett (ca) Wikipedia - Equazione di Hammett (it) Wikipedia - Hammett equation (en) Wikipedia - Hammett-yhtälö (fi) Wikipedia - Équation de Hammett (fr) Wikipedia - ハメット則 (ja) Hammett equation (Hammett relation)

https://doi.org/10.1351/goldbook.H02732
The equation in the form: $\log _{10}(\frac{k}{k_{0}}) = \rho \ \sigma$ or $\log _{10}(\frac{K}{K_{0}}) = \rho \ \sigma$ applied to the influence of meta- or para-substituents X on the reactivity of the @F02555@ Y in the benzene derivative m- or p-XC6H4Y. $$k$$ or $$K$$ is the rate or @E02177@, respectively, for the given reaction of m- or p-XC6H4Y; $$k_{0}$$ or $$K_{0}$$ 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 $$\log _{10}k_{0}$$ or $$\log _{10}K_{0}$$ written as a separate term on the right hand side, e.g. $\log _{10}k = \rho \ \sigma +\log _{10}k_{0}$ or $\log _{10}K = \rho \ \sigma +\log _{10}K_{0}$ It then signifies the intercept corresponding to X = H in a regression of $$\log _{10}k$$ or $$\log _{10}K$$ on $$\sigma$$.