A ketone can be prepared from the reaction of a nitrile with a Grignard reagent. Describe the intermediate formed in this reaction, and show how it can be converted to a ketone.

Verified step by step guidance

1. Identify the starting materials: a nitrile (R-C≡N) and a Grignard reagent (R'-MgX).
2. Understand that the Grignard reagent acts as a nucleophile, attacking the electrophilic carbon in the nitrile, forming an imine salt intermediate.
3. Recognize that the imine salt intermediate is an anion with the structure R-C(=N^-)-R'.
4. Hydrolyze the imine salt intermediate by adding water or an acid, which converts the imine to a ketone (R-C(=O)-R').
5. Conclude that the overall transformation involves the conversion of a nitrile to a ketone via the formation and hydrolysis of an imine salt intermediate.

Key Concepts

Nitrile Structure and Reactivity

Nitriles are organic compounds containing a cyano group (-C≡N), which is a carbon triple-bonded to a nitrogen atom. They are polar and can act as electrophiles in reactions. When treated with Grignard reagents, nitriles undergo nucleophilic addition, where the nucleophile (from the Grignard reagent) attacks the electrophilic carbon of the nitrile, leading to the formation of an intermediate.

Grignard Reagents

Grignard reagents are organomagnesium compounds represented as R-MgX, where R is an organic group and X is a halogen. They are highly reactive nucleophiles that can add to electrophilic centers, such as carbonyls and nitriles. In the reaction with nitriles, the Grignard reagent adds to the carbon of the cyano group, forming a tetrahedral intermediate that can further react to yield a ketone.

Conversion to Ketone

The intermediate formed from the reaction of a nitrile with a Grignard reagent is a ketimine, which can be hydrolyzed to yield a ketone. This hydrolysis involves the addition of water, leading to the cleavage of the C-N bond and the formation of a carbonyl group (C=O). The overall transformation illustrates the utility of Grignard reagents in synthesizing ketones from nitriles.