Question

Explain why (S)-2-butanol forms a racemic mixture when it is heated in sulfuric acid.

a) When (S)-2-butanol loses water, the asymmetric center in the reactant becomes a planar sp2 carbon. Therefore, the chirality is lost. When sulfuric acid attacks the carbocation, it can attack from either side of the planar carbocation, forming [(R)-2-butan-2-yloxy]sulfonic acid and [(S)-2-butan-2-yloxy]sulfonic acid with equal ease. Which are hydrolysed to form racemic mixture.

b) When (S)-2-butanol loses water, the asymmetric center in the reactant becomes a planar sp2 carbon. Therefore, the chirality is lost. When water attacks the carbocation, it can attack from either side of the planar carbocation, forming (S)-2-butanol and (R)-2-butanol with equal ease.

c) Sulfuric acid attacks the (S)-2-butanol to form [(S)-2-butan-2-yloxy]sulfonic acid. Which is hydrolysed to form (S)-2-butanol and (R)-2-butanol with equal ease.

d) None of above.

Answer 1

Therefore, correct option is (b).