Which reagent is most suitable for the conversion of an alkyl chloride to an alkyl fluoride?

Solution

1. The conversion of alkyl chlorides to alkyl fluorides is known as the Swarts reaction.
2. Alkali metal fluorides like $\text{NaF}$ or $\text{KF}$ are generally poor nucleophiles in these conditions due to low solubility.
3. Heavy metal fluorides such as $\text{AgF}$, ${\text{Hg}}_2{\text{F}}_2$, or ${\text{SbF}}_3$ are effective reagents.
4. The precipitation of the corresponding metal chloride drives the reaction to completion.
5. Hence the answer is (B).