Chemistry - Halogen Derivative Question with Solution | TestHub

Question Explanation:

Identifying compounds that undergo E1cB reaction.

Concept:

E1cB reaction mechanism, Carbanion stability

Solution:  

More is stability of carbanion more is reactivity of R X via E₁cb. Presence of EWG stabilizes carbanion. Options 1 and 2 have a carbonyl group and a cyano group (–CN), respectively, adjacent to the β- hydrogen, making the β-hydrogen highly acidic and the intermediate carbanion stable. The leaving group F is a poor leaving group in option 1 and –CN is a poor leaving group in option 2, which favors the E1cB mechanism. Between the two, –CN is a better stabilizing group for the carbanion than C=O. Both 1 and 2 are possible answers.