A Group Transfer of Biological Interest

The charges on aryl oxide ion ( p) and phenol (c,) oxygen atoms are defined as -1 and zero respectively. The change in effective charge on the oxygen of the phenol is computed to be -1.36 from Equations (25) and (26). 

Hammett p values could have been used in the above example instead of the Bronsted p values (see Appendix 1, Section Al.1.5) as follows peq and Ps are respectively -3.03 and -2.23 the equilibrium (Equation 21) is thus -3.03/-2.23 = 1.36-fold more sensitive to substituent change than is the standard dissociation (Equation 22). The total change in effective charge is therefore -1.36 and the effective charge on the reactant is given by Equation (27) (d = d) yielding the same result as that from the Bronsted methodology (Equation 25). 

---