Evaluate the standard reaction of 2-bromobutane with alcoholic KOH. Which of the following thermodyn — Haloalkanes and Haloarenes Chemistry Question
Question
Evaluate the standard reaction of 2-bromobutane with alcoholic KOH. Which of the following thermodynamic statements accurately capture the characteristics and governing regioselectivity of this specific elimination?
💡 Solution & Explanation
A) True. 2-bromobutane undergoes E2 elimination with a small, highly aggressive strong base like KOH to overwhelmingly yield *trans*-2-butene as the major product, directly following Saytzeff's rule. C) True. The transition state geometrically resembles the final alkene; therefore, factors that stabilize the product alkene (like extended hyperconjugation) actively lower the transition state energy ($E_a$). D) True. It is a classic concerted bimolecular $\beta$ -elimination. Option B is false because hydroxide/ethoxide are exceedingly small bases that readily favor internal Saytzeff products; an intentionally bulky base like potassium *t*-butoxide would be required to physically force the Hofmann product.