Which of the following can not be made by reduction of ketone or aldenhyde with `NaBH_4` ?

Options

A. 1 - Butanol
B. 2 - Butanol
C. 2 - Methyl - 1 - propanol
D. 2 - Methyl - 2 - propanol

Answer

To determine which of the following compounds cannot be made by the reduction of ketones or aldehydes with sodium borohydride (NaBH4), we need to analyze each option:

1. **1-butanol**
2. **2-butanol**
3. **2-methyl-1-propanol**
4. **2-methyl-2-propanol**

### Step-by-Step Solution:

**Step 1: Understand the Reduction Process**
- Sodium borohydride (NaBH4) is a reducing agent that can reduce aldehydes to primary alcohols and ketones to secondary alcohols.

**Step 2: Analyze Each Compound**
- **1-butanol**: This is a primary alcohol. It can be formed by the reduction of butanal (an aldehyde) with NaBH4.
- **Reaction**: Butanal (C4H8O) + NaBH4 → 1-butanol (C4H10O)

- **2-butanol**: This is a secondary alcohol. It can be formed by the reduction of butan-2-one (a ketone) with NaBH4.
- **Reaction**: Butan-2-one (C4H8O) + NaBH4 → 2-butanol (C4H10O)

- **2-methyl-1-propanol**: This is also a primary alcohol. It can be formed by the reduction of 2-methylpropanal (an aldehyde) with NaBH4.
- **Reaction**: 2-methylpropanal (C5H10O) + NaBH4 → 2-methyl-1-propanol (C5H12O)

- **2-methyl-2-propanol**: This is a tertiary alcohol. Tertiary alcohols cannot be formed by the reduction of aldehydes or ketones because they do not have a hydrogen atom on the carbonyl carbon to facilitate the reduction.
- **Conclusion**: 2-methyl-2-propanol cannot be formed from any aldehyde or ketone using NaBH4.

**Step 3: Final Answer**
- The compound that cannot be made by the reduction of ketones or aldehydes with NaBH4 is **2-methyl-2-propanol**.