Hughes-Ingold model

In terms of reactivity and kinetics, a specific effect has therefore been considered this is related to the reaction mechanism and, in particular, ho v the polarity of the system is altered during the progress of the reaction. These assumptions are evidently connected with the Hughes-Ingold model [65], universally adopted to explain solvent effects [26] and, especially, the intervention ofaprotic dipolar solvents. 

Hughes and Ingold, primarily studying substitution and elimination reactions, have extensively investigated the effect of molecular solvents on reactions passing through dipolar-transition states [2]. On the basis of a simple qualitative solvation model, which exclusively considers electrostatic interactions between ions (or dipolar molecules) and solvent molecules in initial and transition states it is generally... 

Using a simple electrostatic model of solvation in nucleophilic substitution reactions, Hughes and Ingold concluded that more polar solvents will preferentially stabilise more polar solutes and proposed a set of rules to predict the outcome of changing the solvent on the rate of a reaction ... 

Ekiel IH, Hughes L, Burton GW, Jovall PA, Ingold KU, Smith ICP. Structure and dynamics of a-tocopherol in model membranes and in solution broad-line and high-resolution NMR study. Biochemistry 1988 27 1432-1440. 

---