Question

In the following sequence of reactions, compound 'M' is:

\( \text{M} \xrightarrow{\text{CH}_3\text{MgBr}} \text{N} + \text{CH}_4 \uparrow \xrightarrow{\text{H}^+} \text{CH}_3\text{COCH}_2\text{COCH}_3 \)

• A. \(\text{CH}_3\text{COCH}_2\text{COCH}_3\)
• B. \(\text{CH}_3\text{COCH}_2\text{CO}_2\text{Et}\)
• C. \(\text{CH}_3 - \text{C} \equiv \text{CH}_3\)
• D. \(\text{CH}_3 - \text{C} \equiv \text{OH}\)

Answer 1

The Correct Option is A

The reaction sequence proceeds in the following stages:

1. Grignard Reaction: Compound \(M\) reacts with \(\text{CH}_3\text{MgBr}\) (Grignard reagent) to yield intermediate \(N\). The Grignard reagent adds to the carbonyl group of \(M\), forming a \(\text{C–C}\) bond and releasing \(\text{CH}_4\) gas. The mechanism involves nucleophilic attack by \(\text{CH}_3^-\) on the carbonyl carbon.

2. Hydrolysis: Intermediate \(N\) undergoes acid hydrolysis, transforming into \(\text{CH}_3\text{COCH}_2\text{COCH}_3\), a \(\beta\)-diketone. Hydrolysis protonates and stabilizes the newly formed compound.

Key Structural Insight: \(\text{CH}_3\text{COCH}_2\text{COCH}_3\) has a \(\beta\)-diketone structure, with two keto groups separated by a \(\text{CH}_2\) group. Therefore, compound \(M\) must be a precursor to this structure.

The final product, \(\text{CH}_3\text{COCH}_2\text{COCH}_3\), matches the given options.

Therefore, the correct answer is Option 1.