Kinetic parameters of ionizing power of solvents. The nature of solvation effects in heterolysis of 2-aryl-2-chloroadamantanes

Abstract

Aim. To find out the possibility of using tertiary substrates as benchmarks for determining the kinetic parameters of the ionizing ability of solvents Y.Results and discussion. The rate of heterolysis of tertiary substrates, especially adamantyl derivatives, is highly dependent on the effect of nucleophilic solvation. This effect increases with increasing spatial complications. The use of 2-aryl-2-halogenadamantanes as reference points is impractical because the conjugation of the positive charge with the phenyl strongly depends on the nature of the solvent. The least sensitive to the effects of specific solvation is tBuCl. Unlike tertiary compounds, the heterolysis rate of secondary ones does not depend on the nucleophilicity of the solvent.Experimental part. The kinetic data of tertiary substrates obtained by different methods (conductometric, chromatographic, verdazyl) were generalized using correlation analysis.Conclusions. Tertiary substrates are unsuitable as benchmarks for determining the ionizing ability of solvents due to the negative effect of nucleophilic solvation. Secondary substrates are less sensitive to the effects of specific solvation. The rate of heterolysis of secondary substrates is described by the parameters of polarity f(ɛ) and electrophilicity E or solvatochromic parameters of the ionizing capacity of the solvent Z(ЕТ).Received: 25.06.2020 Revised: 15.07.2020 Accepted: 27.08.2020