This reaction is an example of SN₂ reaction since, there is absence of steric hindrance and lack of stable carbocation formation. A SN₂ reaction is a Nucleophilic Substitution bimolecular reaction, where breaking and formation of bonds occurs simultaneously.

Here, Nucleophile acetylide ion containing one lone pair of electron attacks on the reactant substrate to make the leaving group Br^- ion which contains three lone pair of electrons leave.