An SN2 (substitution nucleophilic bimolecular) reaction is a type of organic reaction in which a nucleophile (electron-rich species) replaces a leaving group (electron-poor species) on an organic compound. It is a second-order reaction, meaning the rate is dependent on the concentrations of both the nucleophile and the substrate.
The reactivity of a compound in an SN2 reaction can be predicted by considering three factors: the strength of the nucleophile, the steric hindrance around the reaction site, and the leaving group ability of the substrate. Generally, a strong nucleophile, low steric hindrance, and good leaving group will result in a more reactive compound.
The five compounds commonly used to predict SN2 reactivity are methyl chloride, ethyl chloride, isopropyl chloride, tert-butyl chloride, and chlorobenzene.
The structure of a compound can affect its reactivity in an SN2 reaction in several ways. A bulky or hindered structure can slow down the reaction due to steric hindrance, while a more compact structure with less steric hindrance will be more reactive. Additionally, the presence of electron-donating or electron-withdrawing groups can also affect the reactivity of a compound.
There are a few limitations when using SN2 reactions to predict reactivity. First, the reaction conditions and solvent can greatly impact the rate of the reaction. Additionally, the presence of other functional groups on the compound can affect the reaction. It is also important to consider the stereochemistry of the compound, as SN2 reactions can result in inversion of stereochemistry at the reaction site.