Question

What is the major product when 2-bromopentane reacts with alcoholic KOH?

• A. Pent-1-ene
• B. Pent-2-ene
• C. Pentanol
• D. Pentanal

Hint:

Alcoholic KOH favors elimination reactions producing alkenes. According to Saytzeff's rule, the major product is the more substituted alkene.

Answer 1

The Correct Option is B

Concept: Alcoholic KOH promotes elimination reactions (E2 mechanism) in alkyl halides, leading to the formation of alkenes. According to Saytzeff's rule, the more substituted alkene is the major product.

Step 1: Identify the reaction type. 2-bromopentane reacts with alcoholic KOH via β-elimination, removing a hydrogen atom from the β-carbon and bromine from the α-carbon.

Step 2: Apply Saytzeff's rule. The elimination favors formation of the more substituted alkene. Therefore, pent-2-ene is formed as the major product rather than pent-1-ene. Thus, \[ \boxed{\text{Pent-2-ene}} \]