Question

Choose the correct order of reactivity for dehydration of the given alcohols using concentrated sulfuric acid

• A. 2- methylpropan-2-ol > 2- butanol> 1- butanol
• B. 2- methylpropan-2-ol > 1 - butanol> 2- butanol
• C. 2- butanol> 2- methylpropan -2-ol > 1- butanol
• D. 1 -butanol> 2-butanol > 2- methylpropan -2-ol

Answer 1

Answer: (A)

As both $E_1$ and $E_2$ elimination is preferred if leaving group is at 3° carbocation, then 2° carbon and then at 1° carbon. In case of 2-methylpropan-2-ol, 2-butanol and 1-butanol the leaving group $H_3{O}^{+}$ is at 3°, 2° and 1° carbon respectively, so dehydration follows the order in given option (a).