Which of the following compound gives a ketone with Grignard reagent?

Options

A. Formaldehyde
B. Ethyl alcohol
C. Methyl cyanide
D. Methyl iodide

Answer

To determine which compound gives a ketone with a Grignard reagent, we can analyze the reaction of methyl cyanide (also known as acetonitrile) with a Grignard reagent.

### Step-by-Step Solution:

1. **Identify the Grignard Reagent**:
- A Grignard reagent is typically represented as RMgX, where R is an alkyl or aryl group and X is a halogen. In this case, we will consider methyl magnesium bromide (CH₃MgBr).

2. **Understand the Reactivity of Methyl Cyanide**:
- Methyl cyanide (CH₃CN) contains a nitrile functional group (–C≡N). Nitriles can react with Grignard reagents to form ketones.

3. **Reaction Mechanism**:
- When methyl cyanide reacts with the Grignard reagent, the nucleophilic carbon of the Grignard reagent attacks the electrophilic carbon of the nitrile group:
\[ CH₃CN + CH₃MgBr \rightarrow CH₃C(=N)CH₃MgBr \]
- This forms a magnesium complex.

4. **Hydrolysis**:
- Upon hydrolysis (reaction with water), the intermediate converts into a ketone:
\[ CH₃C(=N)CH₃MgBr + H₂O \rightarrow CH₃C(=O)CH₃ + Mg(OH)Br \]
- The product formed is acetone (propane-2-one), which is a ketone.

5. **Conclusion**:
- Therefore, methyl cyanide is the compound that gives a ketone (acetone) when reacted with a Grignard reagent.

### Final Answer:
The correct option is **methyl cyanide (option C)**.

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