Question

cyanide+ DIBAL-H

• A. Aldehyde (R-CHO)
• B. Primary Amine (R-CH₂NH₂)
• C. Carboxylic Acid (R-COOH)
• D. Ketone (R-CO-R')

Answer 1

Answer: (A), (B)

Aldehyde (R-CHO) and Primary Amine (R-CH₂NH₂)

Answer 2

The reaction of a nitrile (R-C≡N) with Diisobutylaluminium hydride (DIBAL-H) is a reduction. The outcome depends on the stoichiometry of DIBAL-H and reaction temperature.

1. Formation of Aldehyde: Using one equivalent of DIBAL-H at low temperatures (e.g., -78°C) followed by acidic hydrolysis selectively reduces nitriles to aldehydes. The general equation is: $\text{R}-\text{C}\equiv\text{N} \xrightarrow[\text{2. H}_3\text{O}^+]{\text{1. DIBAL-H (1 eq), low temp}} \text{R}-\text{CHO}$

2. Formation of Primary Amine: If an excess of DIBAL-H is used or the reaction is carried out at higher temperatures, the intermediate imine or the initially formed aldehyde can be further reduced, leading to a primary amine. $\text{R}-\text{C}\equiv\text{N} \xrightarrow{\text{Excess DIBAL-H, heat}} \text{R}-\text{CH}_2\text{NH}_2$

Since the reaction conditions are not specified in the question, both aldehyde and primary amine are considered possible products.