On the empirical scales of organic solvents established using probe/homomorph pairs

Abstract

A critical analysis on the adequacy of empirical solvent scales established using probe/homomorph pairs is performed. The independence and robustness of the solvent scales SP (solvent polarizability), SdP (solvent dipolarity), SA (solvent HBD acidity), and SB (solvent HBA basicity) resulting from this approach are also verified. The nature of the solute/solvent molecular interactions that control the values of the Reichardt E T (30) scale is again revealed, it being independent on the solvent polarizability.

The Global Polarity of Alcoholic Solvents and Water – Importance of the Collectively Acting Factors Density, Refractive Index and Hydrogen Bonding Forces

“…New findings on the liquid structure of HFIP and TFE from the literature are included in the discussion at appropriate points with references. Moreover, due to critical comments and comparative considerations in recent works,[ 35 , 36 ] we also feel compelled to consolidate and considerably extend the analysis of alcoholic solvents of our earlier study. [13b] …”

“…New findings on the liquid structure of HFIP and TFE from the literature are included in the discussion at appropriate points with references. Moreover, due to critical comments and comparative considerations in recent works, [35,36] we also feel compelled to consolidate and considerably extend the analysis of alcoholic solvents of our earlier study. [13b] The aim of this work is not to define a new solvent parameter, but to provide a physically correct understanding of known solvent-dependent measurement data in relation to the physical properties (molar mass, density, refractive index) of the solvent, which will be discussed comparatively as alternative approaches.…”

Solvation Effects in Organic Chemistry: A Short Historical Overview

“…In order to overcome some disadvantages of the Taft–Kamlet–Abboud approach, another multiparameter correlation equation was introduced in 1995 and improved in 2009 by Javier Catalán et al at the Universidad Autónoma de Madrid, Spain . The final correlation eq contains four orthogonal solvent parameters for the solvent’s polarizability ( SP ), dipolarity ( SdP ), HBD acidity ( SA ), and HBA basicity ( SB ), derived from three carefully selected, homomorphic pairs of solvatochromic probe dyes, , and has since been successfully employed to a manifold of solvent-dependent processes.…”

“…But at least a sound interpretation of the correlated solvent influence on the process under study is then possible. The discrepancies sometimes found by applications of different multiparameter equations to the same solvent-dependent process are often caused simply by the varying number of solvents used in the respective correlation analysis. − …”

“…Finally, recent correlation analyses of the S N 1/E1 heterolysis reaction of 2-chloro-2-methylpropane, t -BuCl (the reference reaction for Winstein’s Y values) by multiparameter eqs and of Catalán and Laurence should be mentioned as well. The resulting multiple correlation eqs and are as follows with n = 52 and R 2 = 0.963 and with n = 28 and R 2 = 0.976.…”