The effectiveness of solvents as hydrogen bond donors

Abstract

Taft and Kamlet's α-scale of solvent hydrogen bond donation ability is reexamined with regard to its correlations with three widely used polarity scales: Dimroth and Reichardt's E _T (30), Kosower's Z and Mayer's A _N , as well as with the α_m values of the solvents when present as monomeric solutes. The correlation with E _T serves to extend the solvent α-scale according to the expression:

$$\alpha = {{\left[ {E_T - E_{T^ \circ } - s\left( {\pi ^* + d\delta } \right)} \right] - b\beta } \mathord{\left/ {\vphantom {{\left[ {E_T - E_{T^ \circ } - s\left( {\pi ^* + d\delta } \right)} \right] - b\beta } a}} \right. \kern-\nulldelimiterspace} a}$$

where s, b, a, d, π^*, δ, and β have their usual meanings in the context of the Taft and Kamlet scales.