Question

Which of the following compounds undergo E2 reactions with maximum rate?

• A. $CH _{3} C \left( CH _{3}\right)( Br ) CH _{2} CH _{3}$
• B. $CH _{3}\left( CH _{2}\right)_{2} CH _{2} Cl$
• C. $CH _{3}\left( CH _{2}\right)_{2} CH _{2} I$
• D. $CH _{3} C \left( CH _{3}\right)( I ) CH _{2} CH _{3}$

Answer 1

Answer: (D)

Rate of elimination depends on degree of alkyl halide and nature of leaving group. $C-I$ bond is broken easily as iodide is good leaving group. More over, the ease of elimination reaction is in the order $3^{o} \text{alkylhalide} > 2^{o} \text{alkylhalide} > 1^{o} \text{alkylhalide}$ .