Prediction: Substituents with Low-Lying LUMOs will Accelerate the Sn2 by Stabilizing Electron Density from Nucleophile and Leaving Group through Hyperconjugation

The phenomenon of hyperconjugation (or σ-conjugation) may simply be defined as the delocalization of electrons with the participation of bonds of primarily σ-character.

As a result of hyperconjugation, electron density at o- and p- position (w.r.t. methyl group) increases and therefore electrophilic substitution in toluene takes place at o- and p- positions.

In the formalism that separates bonds into σ and π types, hyperconjugation is the interaction of σ-bonds (e.g. C–H, C–C, etc.) with a π network.

Hyperconjugation leads to shortening of sigma (σ) bond. Eg. C – C bond in 1,3-butadiene and methylacetylene is 1.46 A0 in length, much less as compared to 1.54 A0 found in saturated …

May 15, 2012 · Only a handful of references have been made to hyperconjugation in this Journal since the middle previous century. This article considers hyperconjugation in the context of resonance …

The sequence of radical stability may be explained by the differing amounts of hyperconjugation. The more alkyl substituents a radical carbon atom possesses, the more stabilized it becomes from …