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On the nature of modified composite electrical effect parameters
Author(s) -
Charton Marvin,
Charton Barbara I.
Publication year - 2003
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.636
Subject(s) - composite number , chemistry , delocalized electron , exponent , function (biology) , electrical resistivity and conductivity , work (physics) , field (mathematics) , thermodynamics , composite material , quantum mechanics , materials science , physics , mathematics , organic chemistry , pure mathematics , linguistics , philosophy , evolutionary biology , biology
It is shown that a correlation of some property, reactivity or biological activity with pure parameters can also be carried out with composite parameters to produce a model with comparable statistics. Modified composite electrical effect parameters can be obtained from known composite electrical effect parameters by means of an algorithm such as σ X ♦ = (σ X + c ) min which σ X ♦ is the modified composite electrical effect parameter (MCEEP), σ X the original composite electrical effect parameter, c a constant and m an exponent. MCEEPs were calculated from this equation with c equal to 2 and m ranging from −4 to 4 when σ X is σ m or σ p , and from −2 to 2 when it is σ p + . They were used to model 10 sets of chemical reactivities that had previously been correlated with the pure parameters σ 1 , σ d and σ e , which represent the localized (field), intrinsic delocalized (resonance) and electronic demand sensitivity electrical effects, respectively. In most cases both the pure and the modified composite parameters give comparable fits to the data as measured by the values of 100 R 2 , in accord with the prediction. The composition of the MCEEPs was a linear function of m . The advantage in using pure parameters is that they are readily interpretable. Correlations with composite parameters can be interpreted only if their composition has been determined. These results provide an understanding of the way in which topological parameters work. Copyright © 2003 John Wiley & Sons, Ltd.