Question

Identify the product formed when Hex-3-enenitrile is reduced with diisobutylaluminium hydride followed by acid hydrolysis?

• A. Hexanal
• B. Hexan-3-one
• C. Hex-3-enal
• D. Hexanoic acid

Hint:

DIBAL-H: Nitrile $\rightarrow$ Aldehyde (Double bonds remain untouched).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This question tests the selectivity of the reducing agent DIBAL-H on unsaturated nitriles.

Step 3: Detailed Explanation:
Diisobutylaluminium hydride (DIBAL-H) is a selective reducing agent that reduces nitriles (\( \text{-CN} \)) to imines, which on subsequent acid hydrolysis yield aldehydes (\( \text{-CHO} \)).
A crucial property of DIBAL-H is that it does not reduce isolated carbon-carbon double bonds (\( \text{C=C} \)).
Starting material: Hex-3-enenitrile (\( \text{CH}_3\text{CH}_2\text{CH=CHCH}_2\text{CN} \)).
1. Reduction: \( \text{R-CN} \xrightarrow{\text{DIBAL-H}} \text{R-CH=NH} \).
2. Hydrolysis: \( \text{R-CH=NH} \xrightarrow{\text{H}_3\text{O}^+} \text{R-CHO} \).
The product is Hex-3-enal (\( \text{CH}_3\text{CH}_2\text{CH=CHCH}_2\text{CHO} \)).

Step 4: Final Answer:
The final product is Hex-3-enal.