The compound which does not react with lithium aluminium hydride is

Options

A. 3-penten-2-one
B. methyl benzoate
C. 2-pentanol
D. propanenitrile

Answer

To determine which compound does not react with lithium aluminum hydride (LiAlH4), we need to analyze the reactivity of each option provided. LiAlH4 is a strong reducing agent that typically reacts with carbonyl compounds and certain functional groups.

### Step-by-Step Solution:

1. **Understanding LiAlH4**:
- Lithium aluminum hydride (LiAlH4) is a powerful reducing agent that donates hydride ions (H-) to electrophilic centers, primarily carbonyl groups (C=O) and some other functional groups.

2. **Analyzing Each Option**:
- **Option A: 3-pentanone (C5H10O)**:
- Structure: CH3-CO-CH2-CH2-CH3
- Contains a carbonyl group (C=O), which can react with LiAlH4. Therefore, this option can react.

- **Option B: Methyl benzoate (C9H10O2)**:
- Structure: C6H5-CO-OCH3
- Contains a carbonyl group (C=O) and an ester functional group. LiAlH4 can reduce esters and carbonyls, so this option can react.

- **Option C: 2-pentanol (C5H12O)**:
- Structure: CH3-CH(OH)-CH2-CH2-CH3
- This is an alcohol and does not have a carbonyl group. Alcohols do not react with LiAlH4 as they lack an electrophilic center for the hydride to attack. Therefore, this option does not react.

- **Option D: Propionitrile (C3H7N)**:
- Structure: CH3-CH2-C≡N
- Contains a nitrile group (C≡N). LiAlH4 can reduce nitriles to primary amines, so this option can react.

3. **Conclusion**:
- Based on the analysis, the compound that does not react with lithium aluminum hydride is **Option C: 2-pentanol**.

### Final Answer:
The compound which does not react with lithium aluminum hydride is **2-pentanol (Option C)**.