Bocek Kopecky model

Bocek-Kopecky model - Free-Wilson analysis... 

The Bocek-Kopecky analysis is another modified Free-Wilson approach proposed to take into account interaction terms, i.e. nonlinear effects [Bocek et al, 1964 Kopecky et al, 1965]. The Bocek-Kopecky model is defined as ... 

The Bocek Kopecky model is theoretically and practically related to the nonlinear Hansch model [22, 392, 393] and thus to eq. 79. However, due to the large number of variables this modification has never been used. 

The Free-Wilson method (198) and its modifications (212, 213) are all based on the linear additivity assumption. This was criticized by Bocek et al. (215, 216), and the possibility of interactions between substituents was introduced. For two substituents the Bocek-Kopecky interaction model can be expressed by equation 102... 

This equation shows the relationship between the Hansch and the Free-Wilson equations. It has been suggested (217, 220) that the Bocek-Kopecky interaction model holds for the parabolic dependence of biological activity on the partition coefficient. 

It should be mentioned that Bocek and Kopecky, independently and at the same time as Free and Wilson, proposed an additive model with additional interaction terms (eq. 80, reformulated exCy = interaction term) [429, 430]. 

Higher Order Approximations - In the early attempts to correlate structure with activity mathematically, simple linear combinations of physicochemical parameters were usually considered. It has become evident that the addition of interaction terms to such equations can in some Instances yield sharper correlations.Singer and Purcellhave discussed this problem and compared the models of Free and Wilson, Kopecky and Bocek and Hansch and his colleagues. They point out that in view of the many Instances where BR is not linearly > related to log P and where BR is also not linearly related to electronic effects 30 that the model of Free and Wilson will not hold, but that the Kopecky-Bocek model should apply. 

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See also in sourсe #XX -- [ ]

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