Yukawa-Taft equation

See also rho (p) value sigma (a) constant Taft equation Yukawa-Tsuno equation. 

Sections 2 and 3 contain accounts of the Yukawa-Tsuno equation, the dual substituent-parameter (DSP) equation, the extended Hammett (EH) equation, and multiparameter equations derived from Taft s separation of polar, steric, and resonance effects . These equations are not now the only possibilities for multiparameter treatment. In this section we shall give brief accounts of some of the other approaches, with key references for further information. 

Diparametric equation A relationship in which the effect of structure on a property is represented by two parameters, one of which is generally composite. Examples discussed in this work include the LD, CR and MYT equations. Other examples are the Taft, Ehrenson and Brownlee DSP (dual substituent parameter), Yukawa-Tsuno YT and the Swain, Unger, Rosenquist and Swain SURS equations. The DSP equation is a special case of the LDR equation with the intercept set equal to zero. It is inconvenient to use and has no advantages. The SURS equation uses composite parameters which are of poorer quality than... 

The Swain-Lupton, Taft and Dewar-Grisdale equations all require that the substituent in the reaction under investigation remains at the same position relative to the reaction centre. Thus meta and para series have to be treated separately unlike the Yukawa-Tsuno method where both meta and para substituents may be taken together. The Swain-Lupton treatment may be illustrated by the reaction of chloride ion with substituted benzenediazonium chlorides (Figure 7, Equation 26). ... 

Hammett s reaction constants using a values, unless otherwise indicated. By use of the Yukawa and Xsuno equation (see text), c p values by use of Taft s equation (see text). 

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