Q143 / 200 · MHT CET - Medical 2026 (24 April Shift 1) · Chemistry
Identify a final product obtained when Pent-3-enenitrile is treated with $\text{AlH}(i\text{-Bu})_2$ followed by acid hydrolysis.
- APent-3-enol
- BPentanoic acid
- CBut-3-enol
- Correct answerDPent-3-enal
Solution
The structure of Pent-3-enenitrile is $CH_3-CH=CH-CH_2-CN$.
DIBAL-H ($\text{AlH}(i\text{-Bu})_2$) is a selective reducing agent. It reduces nitriles to imines, which upon subsequent acid hydrolysis yield aldehydes. It does not reduce isolated carbon-carbon double bonds.
Therefore, the $-CN$ group is converted to a $-CHO$ group, while the double bond remains intact.
$CH_3-CH=CH-CH_2-CN \xrightarrow[2. H_3O^+]{1. \text{DIBAL-H}} CH_3-CH=CH-CH_2-CHO$
The final product is Pent-3-enal.
Answer: Pent-3-enal
DIBAL-H ($\text{AlH}(i\text{-Bu})_2$) is a selective reducing agent. It reduces nitriles to imines, which upon subsequent acid hydrolysis yield aldehydes. It does not reduce isolated carbon-carbon double bonds.
Therefore, the $-CN$ group is converted to a $-CHO$ group, while the double bond remains intact.
$CH_3-CH=CH-CH_2-CN \xrightarrow[2. H_3O^+]{1. \text{DIBAL-H}} CH_3-CH=CH-CH_2-CHO$
The final product is Pent-3-enal.
Answer: Pent-3-enal
Hence, the correct answer is option: 'D'.