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Which of the following compounds does NOT give an alcohol as the product upon reduction with LiAlH4?

1. CH3-C(=O)-Cl (acetyl chloride)
2. CH3-C(=O)-NH2 (acetamide)
3. CH3-CH(-O-)CH2 (propylene oxide, an epoxide)
4. CH3-C(=O)-O-C(=O)-CH3 (acetic anhydride)

Correct answer: CH3-C(=O)-NH2 (acetamide)

Solution

LiAlH4 is a powerful reducing agent. Acid chloride (CH3COCl) -> primary alcohol (CH3CH2OH). Acetic anhydride -> alcohol. Epoxide -> alcohol. However, acetamide (CH3CONH2) is reduced to ethylamine (CH3CH2NH2), an amine — NOT an alcohol. So acetamide does not give an alcohol on LiAlH4 reduction.

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