Question

What is the number of moles of H atoms required for complete reduction of one mole acetonitrile?

• A. 2
• B. 4
• C. 6
• D. 1

Hint:

Each $\pi$-bond in an organic molecule requires 2 atoms of hydrogen (or 1 mole of $H_2$ gas) for complete saturation. A nitrile ($-C \equiv N$) has two $\pi$-bonds, thus demanding 4 hydrogen atoms total.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Reduction of a nitrile ($R-C \equiv N$) to a primary amine ($R-CH_2-NH_2$) involves adding hydrogen across the triple bond.

Step 2: Formula Application:
$CH_3CN + 4[H] \rightarrow CH_3CH_2NH_2$.

Step 3: Explanation:
Acetonitrile ($CH_3CN$) has a carbon-nitrogen triple bond. To reach the saturated amine (ethylamine), two hydrogen atoms must be added to the carbon and two to the nitrogen. This requires a total of 4 hydrogen atoms (or 2 moles of $H_2$ gas).

Step 4: Final Answer:
The number of moles of H atoms required is 4.