Alkyl groups in organic molecules are NOT inductively electron-releasing

Abstract

It is commonly stated that alkyl groups exert an inductive electron-releasing effect when compared to hydrogen. This information has been given in numerous organic chemistry textbooks over the last 75 years. The evidence for this position is weak, and does not withstand scrutiny, and there is some evidence for the contrary position. We provide a significant body of computational data that clearly show that alkyl groups exert an inductive electron-withdrawing (–I) effect when compared to hydrogen. This revised position is not in conflict with experimental data, since alkyl group inductive effects are small and are likely to be masked by hyperconjugation/polarizability effects (particularly in charged species), and also by solvent effects.