Original scientific paper

https://doi.org/10.5562/cca3934

Isoparametricity Phenomenon in Organic Reactions: Paradoxical Reality

Igor Shpan’ko orcid.org/0000-0002-5207-5595 ; Department of Chemistry, Biology and Biotechnology, Vasil’ Stus Donetsk National University, 21 600-Richchia Str., Vinnytsia 21021, Ukraine

Abstract

This article presents an overview of the systematic study of the difficult-to-perceive unique phenomenon of isoparametricity in nucleophilic substitution reactions at the carbonyl and benzyl electrophilic centers, as well as in nucleophilic oxirane ring-opening reactions. The conducted studies have shown that isoparametric properties of formal polylinear relations are inherent in organic reactions. Before these studies, little experimental evidence of isoparametricity was known. Non-additive multifactor effects on the kinetics and activation parameters of the considered reactions revealed a wide variety of isoparametric points in cross correlations of the structure–structure, structure–solvent, structure–temperature, and solvent–temperature types. At these points, the reacting system loses its sensitivity to the influence of the corresponding factor. Some of these points were passed through and this was accompanied by reversal of the signs of the corresponding sensitivity coefficients because of reactivity reorientation (isoparametricity paradox). The physical reality of widely discussed enthalpy-entropy compensation effect is proved in studied reactions. The prospects for further investigation of isoparametricity phenomenon are considered.

Keywords

aryloxiranes; organic acids; pyridines; kinetics; catalysis; activation parameters; compensation effect; isoparametricity

Hrčak ID:

299620

URI

https://hrcak.srce.hr/299620

Publication date:

11.4.2023.

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