The reaction is a substitution reaction where the bromine atom (Br) attached to the primary carbon is replaced by a methoxy group (-OCH₃) from methanol (CH₃OH). This is an SN2 reaction, which stands for bimolecular nucleophilic substitution.
What is the mechanism?
The oxygen atom in the methanol molecule acts as a nucleophile due to its lone pairs of electrons and will attack the carbon atom that is bonded to the bromine atom.
The nucleophile (oxygen) approaches the carbon atom from the opposite side of the leaving group (Br) because the SN2 reaction proceeds via a backside attack, which leads to the inversion of configuration at the carbon center.
As the oxygen forms a bond with the carbon, the bromine atom leaves with its bonding electrons, forming a bromide ion (Br⁻). The result is the formation of a new compound where the methoxy group has replaced the bromine atom.