Question

A primary alkyl halide would prefer to undergo ___________.

• A. $S_{N}1$ reaction
• B. $S_{N}2$ reaction
• C. $\alpha$-elimination
• D. racemisation

Answer 1

The correct option is B $S_{N}2$ reaction

Primary alkyl halides undergo $S_{N}2$ mechanisms because $1^{\circ }$ substrates have little steric hindrance to nucleophilic attack and $1^{\circ }$ carbocations are relatively unstable. Since primary alkyl halide is least sterically hindered among primary, secondary and tertiary alkyl halides therefore primary alkyl halides undergo $S_{N}2$ reaction.