COMEDK · Chemistry · 25. Haloalkanes and Haloarenes

Which one of the following is a true statement with reference to reaction between 2- Bromo-2-methylpropane and aqueous KOH ?

A The reaction is not favoured by the presence of polar protic solvent.
B The reaction occurs at a slow rate since it follows \(\mathrm{S}_{\mathrm{N}} 2\) mechanism.
C The reaction occurs at a fast rate since the substrate is a tertiary alkyl halide and follows \(\mathrm{S}_{\mathrm{N}} 1\) mechanism.
D The rate of reaction depends on the concentration of the haloalkane and the nucleophile \(\mathrm{OH}^{-}\)

Verified Solution

Answer & Solution

Correct Answer

(C) The reaction occurs at a fast rate since the substrate is a tertiary alkyl halide and follows \(\mathrm{S}_{\mathrm{N}} 1\) mechanism.

Step-by-step Solution

Detailed explanation

The substrate 2-bromo-2-methylpropane is a tertiary alkyl halide. Tertiary alkyl halides undergo nucleophilic substitution primarily via the \(\mathrm{S}_{\mathrm{N}}1\) mechanism because the carbocation intermediate formed is highly stable due to inductive and hyperconjugation…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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