Parameters linear free energy-related

Buydens, L., Coomans, D., Vanbelle, M., Massart, D.L. and Vanden Driessche, R. (1983a). Comparative Study of Topological and Linear Free Energy-Related Parameters for the Prediction of Gas Chromatographic Retention Indices. J.Pharm.ScL, 72,1327. 

We are concerned in this chapter with the mechanism of a reaction, that is, the detailed manner in which it proceeds, with emphasis on the number and nature of the steps involved. There are several means available for elucidation of the mechanism, including using the rate law, and determining the effect on the rate constant of varying the structure of reactants (linear free energy relations) and of outside parameters such as temperature and pressure. Finally chemical intuition and experiments are often of great value. These means will be analyzed. 

The simplest linear free energy relation that has been used to describe the attack of a series of nucleophiles in an SN2 reaction is the Swain-Scott relation (Swain and Scott, 1953). In our notation the relation becomes (45), where the nucleophilicity parameter for X, x, is defined by (46) or its equivalent (47)... 

Finally, we would like to emphasize that, besides obtaining values of ccfrom the Marcus analysis, another great advantage is that one can separate kinetic and thermodynamic contributions to the parameters in linear free-energy relations. In this article we have done this for the Swain-Scott nucleophilicity parameter n, for m describing the change of reaction rate with solvent, and for the Hammett p-values. 

Verloop, A., Tipker, J. Use of Linear Free Energy Related and Other Parameters in the Study of Fungicidal Selectivity. Pest. Sci. 1976, 7, 379-390. 

For the purpose of correlation analysis or linear FREE-ENERGY RELATIONS, various scales of steric parameters have been proposed, notably A values, Taft s Es, and Charton s u scales. 

Another potential use of this linear free-energy related method in custom tailoring a drug is parameter optimization. Once a particular series of data has been analyzed, one may evaluate r0 for the series and make this the starting point in suggesting molecules for further synthesis and testing. Use of this approach also might indicate that a different series of compounds should be considered if optimum parameters have already been achieved in the compounds tested (1). 

This is the first observed behaviour of the type for Vaska s compound, and the higher A 2 values for the less basic phosphines are also unusual and a consequence of the L dissociation mechanism. The linear free-energy relation between and the Hammett polar transition state such as (16). 

Linear Free-Energy-Related Model - On the other hand, more emphasis has been placed on the correlation of observed biological activity with measured physicochemical parameters of related compounds than in previous years. Hansch has given the historical development of the use of substituent constants and certain physicochemical parameters in quantitative structure-activity studies of biochemical systems. Specifically, he has dealt with the dependence of biological activity of drug molecules upon partitioning properties, electronic parameters, and steric effects. "... 

In equations 9 and 10, de and dA are the kinetic diameters of the larger and smaller penetrants, respectively. The parameters a and b in equation 11 are from the linear free energy relation between activation energy of diffiision,, and, the front... 

Table 3.6 Examples of Simple One-Parameter Linear Free Energy Relationships (LFERs) for Relating Partition Constants and/or Partition Coefficients in Different Two-Phase Systems (Including the Pure Compound as Phase)...

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