Question

Why are ${{\rm{S}}_{\rm{N}}}{\rm{1}}$ reactions generally carried in polar solvents?

Answer 1

We know that the polar solvents are those solvents in which the hydrogen atoms are bonded with the compound nitrogen, oxygen or the halogens. The solvent which consists of labile hydronium ions this solvent is generally termed as the protic solvent.

Complete step by step solution
As we all know, the nucleophilic substitution carries two reactions one is ${{\rm{S}}_{\rm{N}}}{\rm{1}}$ and other is ${{\rm{S}}_{\rm{N}}}2$. The ${{\rm{S}}_{\rm{N}}}{\rm{1}}$ reaction is two-step reaction while ${{\rm{S}}_{\rm{N}}}2$ is a single step. In ${{\rm{S}}_{\rm{N}}}{\rm{1}}$ reaction “SN” represents the nucleophilic substitution, and $1$ represents the rate determining step of the given chemical reaction is one. The ${{\rm{S}}_{\rm{N}}}{\rm{1}}$ reaction is one of the unimolecular chemical reaction while ${{\rm{S}}_{\rm{N}}}2$ is one of the bimolecular chemical reaction.

The ${{\rm{S}}_{\rm{N}}}{\rm{1}}$ reaction generally carried in polar solvents or protic solvents because it usually stabilizes the intermediate carbocation. The favorable polar solvents like methanol or methyl alcohol generally have a permanent dipole which shows that the molecules’ partial negative charge will contain dipole-dipole interactions along with the carbocation and stabilizing the chemical reaction. The polar solvent also reduces the reactivity or reaction capacity of the nucleophile, and it enhances or increases the chances for ${{\rm{S}}_{\rm{N}}}{\rm{1}}$ reaction. Hence, ${{\rm{S}}_{\rm{N}}}{\rm{1}}$ reaction generally occurs in polar solvents.

Note:
The nucleophilic reaction is that reaction in which electrons pairs are donated with the help of the species termed as the nucleophile. It is one of the fundamental reactions in organic chemistry.