Question

Identify the correct decreasing order of ease of dehydrohalogenation of alkyl halides.

• A. 2° > 3° > 1°
• B. 1° > 3° > 2°
• C. 1° > 2° > 3°
• D. 3° > 2° > 1°

Answer 1

Answer: (D)

3° > 2° > 1°

Answer 2

Dehydrohalogenation is a reaction in which a hydrogen halide (HX) is eliminated from an alkyl halide, resulting in the formation of an alkene. The ease of dehydrohalogenation depends on the stability of the carbocation intermediate formed during the reaction.
In general, tertiary (3°) alkyl halides are more easily dehydrohalogenated compared to secondary (2°) and primary (1°) alkyl halides. This is because tertiary carbocations are more stable than secondary and primary carbocations due to the presence of more alkyl groups, which provide electron-donating inductive and hyperconjugation effects.
Therefore, the correct decreasing order of ease of dehydrohalogenation of alkyl halides is (D) 3° > 2° > 1°.