Solvent property scales Drago

Much attention has been given to correlating A// against properties of the interacting species. Two of the most common are the Gutmann [96] donor number, DN, or acceptor number, AN, scales and the Drago [97] E C formulation. The donor number, DN, quantifies the Lewis basicity of a variety of solvents and was defined for a given base B as the exothermic heat of its reaction with the reference acid, antimony pentachloride, in a 10 - M solution in a neutral solvent (1,2-dichloroethane). The units are (kJ/mol). Specifically ... 

Drago has proposed a "unified scale of solvent polarities" based on an extension of the E and C acid and base parameters discussed above. Each solvent is characterized by a parameter S and the change in some property, A%, of a probe system is given hy Ax = PS + W, where P and W are constants for Ae probe. If the probe is an acceptor (Lewis acid) in a donor solvent, then... 

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