Which nucleophile would you expect to add reversibly to an α,β-unsaturated carbonyl?

Question

Quizplus · Accepted Answer

NaCN is a strong nucleophile and is able to add reversibly to an α,β-unsaturated carbonyl. The other options involve weaker nucleophiles or nucleophiles that are not suitable for reversible addition. NaBHS, CH3Li, and LiAlH4 are all strong reducing agents and would not undergo reversible addition while Grignard reagents (such as the one in option C) are not suitable for reversible addition due to their tendency to undergo irreversible addition and subsequent elimination reactions.

Which Nucleophile Would You Expect to Add Reversibly to an α,β-Unsaturated