text: Finally, this type of plot can readily be drawn to illustrate the effects of changing parameters in the acid-catalyzed nucleophilic addition to carbonyls. The example in Figure 4 demonstrates the effects of increasing the strength of the acid. In this case, the extent of protonation is the α-value in the Brønsted catalysis equation. The fact that the α-value remains unchanged explains the linearity of Brønsted plots for such a reaction.
  Ultimately, the More O’Ferrall–Jencks plots have qualitative predictive and explanatory power regarding the effects of changing substituents and reaction conditions for a wide variety of reactions.