Steric and electronic effects in SN2 reactions*

This article gives an overview of recently published literature on the factors that govern SN2 reactivity. By comparing reactivity in solution with that in the isolated gas phase, it has become possible to dissect the contribution of the solvent from that of the intrinsic molecular properties. This has proven to be an extremely important and fruitful step forward in obtaining key knowledge not available before. The gas-phase studies have made it clear that organic chemists need to revise radically their concepts and ideas about this crucial reaction type. This is particularly true with regard to the commonly used term “steric effect”.