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

The D HBD quantity represents the hydroxyl group density of alcoholic solvents or water. D HBD is purely physically defined by the product of molar concentration of the solvent ( N ) and the factor Σn=n× f which reflects the number n and position ( f ‐factor) of the alcoholic OH groups per molecule. Whether the hydroxyl group is either primary, secondary or tertiary is taken into account by f . Σn is clearly linearly correlated with the physical density or the refractive index of the alcohol derivative. Relationships of solvent‐dependent UV/Vis absorption energies as E T (30) values, 129 Xe NMR shifts and kinetic data of 2‐chloro‐2‐methylpropane solvolysis with D HBD are demonstrated. It can be shown that the E T (30) solvent parameter reflects the global polarity of the hydrogen bond network rather than specific H‐bond acidity. Significant correlations of the log k 1 rate constants of the solvolysis reaction of 2‐chloro‐2‐methylpropane with D HBD show the physical reasoning of the approach.