Which one of the following compounds on reduction with `LiAIH_(4)` yeilds a secondary amine?

Options

A. Methyl cyanide
B. Nitroethane
C. Methyl isocyanide
D. Acetamide

Answer

To solve the question of which compound yields a secondary amine upon reduction with lithium aluminum hydride (LiAlH₄), we will analyze each option step by step.

### Step 1: Understand the Reactivity of LiAlH₄
LiAlH₄ is a strong reducing agent that can reduce various functional groups, including:
- Aldehydes to primary alcohols
- Ketones to secondary alcohols
- Esters to alcohols
- Carboxylic acids to alcohols
- Nitriles to primary amines
- Isonitriles to secondary amines

### Step 2: Analyze Each Compound
1. **Methyl Cyanide (CH₃C≡N)**:
- Upon reduction with LiAlH₄, methyl cyanide will yield a primary amine:
\[ \text{CH}_3C≡N \xrightarrow{\text{LiAlH}_4} \text{CH}_3CH₂NH₂ \]
- **Result**: Primary amine.

2. **Nitro Ethyl (CH₃CH₂NO₂)**:
- Reduction with LiAlH₄ will convert nitro ethyl to a primary amine:
\[ \text{CH}_3CH_2NO_2 \xrightarrow{\text{LiAlH}_4} \text{CH}_3CH_2NH₂ \]
- **Result**: Primary amine.

3. **Methyl Isocyanate (CH₃N≡C)**:
- Reduction with LiAlH₄ will yield a secondary amine:
\[ \text{CH}_3N≡C \xrightarrow{\text{LiAlH}_4} \text{CH}_3NHCH_3 \]
- **Result**: Secondary amine.

4. **Acetamide (CH₃CONH₂)**:
- Reduction with LiAlH₄ will yield a primary amine:
\[ \text{CH}_3CONH_2 \xrightarrow{\text{LiAlH}_4} \text{CH}_3CH_2NH₂ \]
- **Result**: Primary amine.

### Step 3: Conclusion
From the analysis, the only compound that yields a secondary amine upon reduction with LiAlH₄ is **Methyl Isocyanate (option 3)**.

### Final Answer:
The compound that yields a secondary amine upon reduction with LiAlH₄ is **Methyl Isocyanate (CH₃N≡C)**.

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