Question

Identify the product ' B ' in the following reaction sequence.
Alkyl halide \(\xrightarrow{\text{Mg/Dry ether}} \text{A} \xrightarrow{\text{NH}_3} \text{B}\)

• A. Alkyl magnesium halide
• B. Alkyl amine
• C. Hydrocarbon
• D. Alkyl nitrile

Hint:

Grignard + proton donor → hydrocarbon.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Alkyl halides react with magnesium in dry ether to form Grignard reagents (\(\text{R-Mg-X}\)). Grignard reagents are highly reactive and act as strong bases; they react instantly with any compound containing active hydrogen (protic compounds).
Step 2: Key Formula or Approach:
1. \(\text{R-X} + \text{Mg} \xrightarrow{\text{ether}} \text{R-Mg-X}\) (Product A)
2. \(\text{R-Mg-X} + \text{H-Z} \longrightarrow \text{R-H} + \text{Mg(Z)X}\)
Step 3: Detailed Explanation:
In step 1, the alkyl halide reacts with magnesium to give 'A', which is an alkyl magnesium halide (Grignard reagent).
In step 2, the Grignard reagent reacts with ammonia (\(\text{NH}_3\)). Ammonia has active hydrogen atoms (\(\text{H-NH}_2\)). The nucleophilic alkyl group (\(\text{R}^-\)) of the Grignard reagent abstract a proton from ammonia to form an alkane (hydrocarbon).
Reaction: \[ \text{R-Mg-X} + \text{NH}_3 \longrightarrow \text{R-H} + \text{Mg(NH}_2\text{)X} \] The organic product 'B' is \(\text{R-H}\), which is a hydrocarbon.
Step 4: Final Answer:
Product B is a hydrocarbon.