Question

In the reaction

The compound ‘B’ is (A) Acetic acid (B) Acetone (C) Acetaldehyde (D) Ethyl alcohol

Answer 1

Hint: The reaction of nitrile with Grignard reagent will result in the formation of compound ‘A’. This compound ‘A’ will then get hydrolysed to form the compound ‘B’. We have to identify the final compound ‘B’ formed after hydrolysis.

Complete Step by Step Solution:
The reaction involves the reaction between the nitrile group and the Grignard reagent.
Firstly, we should understand the nature of the nitrile group. The nitrile group (or cyano group) is electron-withdrawing in nature. The nitrile ($-CN$) group is less basic than other nitrogen-containing compounds such as amines. It is polar in nature. The Grignard reagent ($RMgX$) is prepared by the reaction of an alkyl halide ($RX$) with magnesium ($Mg$). The Grignard reagent helps in the formation of carbon-carbon bonds.

The first step of the reaction is the nucleophilic attack of the Grignard reagent. The reaction between nitrile and Grignard reagent proceeds through the formation of imines. This will get hydrolysed to yield a ketone. So, as in the given reaction, methyl cyanide ($C{{H}_{3}}CN$) is treated with methyl magnesium iodide ($RMgI$), and an imines is formed. This will get hydrolysed and yield acetone ($C{{H}_{3}}COC{{H}_{3}}$ )

Hence, in the above reaction, the compound ‘B’ is acetone ($C{{H}_{3}}COC{{H}_{3}}$ ).
Correct Option: (B) Acetone.

Note: The Grignard reagent ($RMgX$) on treatment with carbon dioxide ($CO_{2}^{{}}$) can form a carboxylic acid ($RCOOH$ ). Also, on treatment of acyl chlorides with dialkyl cadmium, prepared by the reaction of cadmium chloride with Grignard reagent, gives ketones.