Which reagent is most suitable for the conversion of ${\text{C}}_6{\text{H}}_5{\text{CH}}_2{\text{CH}}_2\text{OH}$ to ${\text{C}}_6{\text{H}}_5{\text{CH}}_2{\text{CH}}_2\text{Br}$?

Solution

1. Conversion of primary alcohols to alkyl bromides is best achieved using ${\text{PBr}}_3$.
2. ${\text{PBr}}_3$ avoids the formation of carbocation intermediates that could lead to rearrangements.
3. Other reagents like $\text{HBr}$ or $\text{NaBr}/{\text{H}}_2{\text{SO}}_4$ may cause side reactions or rearrangements in more complex substrates.
4. Hence the answer is (A).