Question: 63. The major product formed in dehydrohalogenation reaction of 2-Bromo pentane is Pent-2-ene. This product formation is based on?
(1) Saytzeff’s Rule
(2) Hund’s Rule
(3) Hofmann Rule
(4) Huckel’s Rule
Answer: Option (1)
Explanation:
Dehydrohalogenation is an elimination reaction in which a hydrogen atom and a halogen atom are removed from adjacent carbon atoms to form an alkene.
According to Saytzeff’s rule, during elimination reactions, the more substituted alkene is formed as the major product.
In 2-bromopentane, removal of hydrogen from the beta-carbon having fewer hydrogen atoms leads to the formation of pent-2-ene.
Pent-2-ene is more substituted and hence more stable than pent-1-ene.
Therefore, the major product pent-2-ene is formed according to Saytzeff’s rule.
Hence, the correct answer is option (1).