Drago solvent polarity scale

Drago, R. S. (1992). J. Org. Chem. 61, 6547. A paper dealing with the analysis of solvent polarity scales. 

Drago developed a universal polarity scale (the S scale) from more than three hundred spectral data (electronic transitions, F and N chemical shifts and RSE coupling constants) for 30 solutes in 31 non-protic solvents from cyclohexane to propylene carbonate. He used the equation... 

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... 

A unified scale of solvent polarities, taking into account both the non-specific and specific donor acceptor interactions of these solvents with solute probes, was introduced by Drago and co-workers and shown in its mathematical form below [17] ... 

Drago RS, Hirsch MS, Ferris DC, Chronister CW A unified scale of solvent polarities for specific and non-specific interactions. J Chem Soc Perkin Trans 2 1994, 2 219-230. 

Drago s EJC analysis and Gutmann s donor/acceptor approach [53, 67] have been compared [200, 217, 218], Eq. (2-12) has been extended for specific and nonspecific interactions between solutes and polar solvents [219]. Various Lewis acidity and basicity scales for polar solvents have been examined and compared by Fawcett, who concluded that the donor/acceptor scales of Gutmann seem to be the most appropriate [341],... 

It should be noted that the S values originally used by Drago" " to describe the polarity of 27 solvents are well correlated with the corresponding values on our dipolarity (SdP) scale (n = 27, r = 0.961). 

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