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 determine which compound yields a secondary amine upon reduction with lithium aluminum hydride (LiAlH4), we need to analyze the given compounds and their structures. A secondary amine is characterized by a nitrogen atom bonded to two carbon atoms and one hydrogen atom.

### Step-by-Step Solution:

1. **Identify the Compounds**: The question implies that we have several compounds to consider. The compounds mentioned in the video are:
- Methyl Cyanide (CH3CN)
- Nitromethane (C2H5NO2)
- Methyl Isocyanate (CH3NCO)
- Acetamide (CH3CONH2)

2. **Understand the Reduction Process**: LiAlH4 is a strong reducing agent that can reduce various functional groups. When we reduce nitriles, isocyanates, or amides, we need to determine the products formed.

3. **Analyze Methyl Cyanide (CH3CN)**:
- When methyl cyanide is reduced with LiAlH4, it converts to CH3CH2NH2 (ethylamine), which is a primary amine, not a secondary amine.

4. **Analyze Nitromethane (C2H5NO2)**:
- Reducing nitromethane with LiAlH4 yields C2H5NH2 (ethylamine), which is also a primary amine.

5. **Analyze Methyl Isocyanate (CH3NCO)**:
- When methyl isocyanate is reduced with LiAlH4, it forms CH3NHCH3 (dimethylamine), which is a secondary amine. This is because the nitrogen is bonded to two methyl groups and one hydrogen.

6. **Analyze Acetamide (CH3CONH2)**:
- Reducing acetamide with LiAlH4 results in CH3CH2NH2 (ethylamine), which is a primary amine.

7. **Conclusion**: Among the compounds analyzed, methyl isocyanate (CH3NCO) is the only compound that yields a secondary amine (dimethylamine) upon reduction with LiAlH4.

### Final Answer:
The compound that yields a secondary amine upon reduction with LiAlH4 is **Methyl Isocyanate (CH3NCO)**.

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