Question

The ease of dehydrohalogenation of alkyl halide with alcoholic KOH is

• A. 3 ${}^{\circ }$ < 2 ${}^{\circ }<$ 1 ${}^{\circ }$
• B. 3 ${}^{\circ }$ > 2 $°>$ 1 ${}^{\circ }$
• C. 3 ${}^{\circ }$ < 2 ${}^{\circ }>$ 1 ${}^{\circ }$
• D. 3 ${}^{\circ }$ > 2 ${}^{\circ }<$ 1 ${}^{\circ }$

Answer 1

Answer: (B)

Such dehydrohalogenation follow $E_2$ mechanism. The driving force of such reaction is the stability of alkene produced. Since, tertiary alkyl halide can give more substituted alkene, it reacts fastest followed by secondary and primary $i.e.,3^{\circ }>2^{\circ }>1^{\circ }.$