Question

Which of the following reagents is used to convert -CN group to -\(\text{CH}_2\text{NH}_2\) group?

• A. \(\text{CrO}_3\)
• B. \(\text{Na}+\text{C}_2\text{H}_5\text{OH}\)
• C. \(\text{H}_3\text{PO}_4\)
• D. \(\text{Al}_2\text{O}_3\)

Hint:

Nitriles are reduced to primary amines by nascent hydrogen from sodium and ethanol or by catalytic hydrogenation.

Answer 1

The Correct Option is B

Step 1: Look at the change.
C is in -CN and -CH2NH2. Four hydrogens are added, so the reagent must be a reducing agent.

Step 2: Pick the reducing agent.
Sodium dissolved in ethanol produces nascent hydrogen, which does exactly this reduction.

Step 3: Eliminate.
$\text{CrO}_3$ oxidises, $\text{H}_3\text{PO}_4$ is an acid and $\text{Al}_2\text{O}_3$ is a catalyst or dehydrating agent.

Final Answer:
Option (B). \[ \boxed{\text{Na + C}_2\text{H}_5\text{OH}} \]