Question

When tert-butyl bromide is heated with silver fluoride, the major product obtained is

• A. 1-Fluorobutane
• B. 2-Fluoro-2-methylpropane
• C. 2-Fluoro-2-methylpropene
• D. 2-Fluorobutane

Hint:

Remember that heating alkyl bromides or chlorides with $\mathrm{AgF}$ is the classic signature of the Swarts Reaction. The carbon skeleton does not rearrange during this straight halogen exchange process, so a tertiary substrate yields a tertiary product.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The query seeks the principal product when a tertiary alkyl bromide, namely tert-butyl bromide, interacts with silver fluoride ($\mathrm{AgF}$) under thermal conditions.

Step 2: Key Formula or Approach:
The transformation of an alkyl halide using metallic fluorides such as $\mathrm{AgF}$, $\mathrm{Hg}_2\mathrm{F}_2$, $\mathrm{CoF}_2$, or $\mathrm{SbF}_3$ to synthesize alkyl fluorides is termed the Swarts reaction. This represents a nucleophilic substitution where the bromide ion gets displaced by a fluoride ion.

Step 3: Detailed Explanation:
Tert-butyl bromide possesses the structural arrangement $(\mathrm{CH}_3)_3\mathrm{C-Br}$.
Upon treatment with silver fluoride ($\mathrm{AgF}$), halogen interchange occurs following a Swarts reaction pathway. The silver cation precipitates with bromide as insoluble $\mathrm{AgBr}$, which pushes the equilibrium forward.
The fluoride nucleophile attacks the tertiary carbocation center, substituting the bromine atom.
$$\mathrm{(CH}_3)_3\mathrm{C-Br} + \mathrm{AgF} \xrightarrow{\Delta} \mathrm{(CH}_3)_3\mathrm{C-F} + \mathrm{AgBr}\downarrow$$ The IUPAC designation of the product $(\mathrm{CH}_3)_3\mathrm{C-F}$ is 2-Fluoro-2-methylpropane.

Step 4: Final Answer:
The major product obtained is 2-Fluoro-2-methylpropane, corresponding to option (B).