Hansch parameter

Fig. 15.21 Calculation of Hansch parameters for three diversity reagent examples with different linkage chemistry.

Fig. 15.22 Display of predicted Hansch parameters of the sum of inductive and resonance constants (F + R) versus lipophilicity (jr) for 302 commercially available carboxylic acids, acid chlorides, sulphonyl chlorides and isocyanates. Symbol size corresponds to larger molecular size (MR). Circles represent the selected R groups and triangles represent the unselected compounds. Colors convey the segmentation of the diversity reagents into nine sectors for selection.

Fig. 15.23 Selected examples for the selection of diversity reagents of 302 choices according to nine sectors selected according to Hansch parameter predictions.

Quantitative, correlative approaches based on hydrophobicity, polarity, and the Hansch parameter have proved to be useful and consistent in aqueous two-phase extraction [12], reversed micellar extraction [13], reversed-phase, hydrophobic interaction [ 14], and ion exchange chromatography [ 15,16], as well as solubiHty in mixed solvents [8,9,17]. 

The type of microbial strain is decisive for the choice of contact between cell and separative force. Pseudomonas species for instance, support direct contact with more polar solvents than Saccharomyces cerevisiae [40], A correlation between the solvent toxicity and its hydrophobicity was obtained by plotting the cellular activity retention against the Hansch parameter logwhich gives the logarithm of the partition coefficient of the solvent in the octanol-water two-phase system [30,76]. 

Darvas [14] had previously taken an important conceptual leap and applied a mathematical technique for optimization— the simplex optimization method—to the lead optimization of natriuretic sulphonamides. By describing molecules by their Hansch parameters (crand it), a common molecule space could be created to describe the series and this space could be walked by the optimization algorithm (Figure 8.4) using the following steps ... 

The inhibition of succinate dehydrogenase from liver flukes in vitro by 25 substituted 2,6-dihydroxybenzanilides has been correlated with the Hansch parameter , suggesting that the distribution of the compound between lipid and aqueous phase and not electronic or steric factors within the series is responsible for the activity.113,114... 

Table 4. Hansch parameters of representative functional groups [30, 31].

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