Question detail

During the addition of a Grignard reagent to an aldehyde, which step occurs immediately after the nucleophile attacks the carbonyl carbon?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Aldehydes and ketones (A-level only)

Question

A. Formation of a carbanion that is immediately protonated.
B. Formation of a tetrahedral alkoxide that is protonated during work‑up.
C. Formation of a carbocation that is stabilized by the Grignard reagent.
D. Formation of a radical intermediate that undergoes hydrogen abstraction.

Answer

Formation of a tetrahedral alkoxide that is protonated during work‑up.

Explanation

A Grignard reagent (RMgX) acts as a strong nucleophile. It attacks the carbonyl carbon, giving a tetrahedral alkoxide. On aqueous work‑up the alkoxide is protonated to yield the alcohol. This is the standard addition mechanism for Grignard reagents to aldehydes.

Common mistake

Misidentifying Nucleophiles

Students often confuse nucleophiles with electrophiles, thinking that nucleophiles are positively charged species.

Remember that nucleophiles are electron-rich species that donate a pair of electrons to form a bond. They are typically negatively charged or neutral molecules with lone pairs.

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