Phenol is less acidic than

Options

A. ethanol
B. o-nitrophenol
C. o-mehtyphenol
D. o-methoxyphenol.

Explanation

To determine which compound phenol is less acidic than, we will analyze the acidity of phenol in comparison to the given options: ethanol, ortho-nitrophenol, ortho-methylphenol, and ortho-methoxyphenol.

### Step-by-Step Solution:

1. **Understanding Phenol's Acidity**:
- Phenol (C6H5OH) can lose a hydrogen ion (H+) to form the phenoxide ion (C6H5O⁻). The stability of this ion is enhanced by resonance, which allows the negative charge to be delocalized over the aromatic ring.

2. **Analyzing Ethanol**:
- Ethanol (C2H5OH) loses H+ to form the ethoxide ion (C2H5O⁻). However, the ethoxide ion does not have resonance stabilization because the negative charge cannot be delocalized. The alkyl group (C2H5) is a +I (inductive effect) group, which destabilizes the negative charge. Therefore, ethanol is less acidic than phenol.

3. **Analyzing Ortho-Nitrophenol**:
- Ortho-nitrophenol (C6H4(NO2)OH) can also lose H+ to form the ortho-nitrophenoxide ion. The nitro group (NO2) is a -M (meta-directing) and -I (inductive) group, which stabilizes the negative charge on the phenoxide ion through resonance. This makes ortho-nitrophenol more acidic than phenol.

4. **Analyzing Ortho-Methylphenol**:
- Ortho-methylphenol (C6H4(CH3)OH) can lose H+ to form the ortho-methylphenoxide ion. The methyl group (CH3) is a +I group, which destabilizes the negative charge. Thus, ortho-methylphenol is less acidic than phenol.

5. **Analyzing Ortho-Methoxyphenol**:
- Ortho-methoxyphenol (C6H4(OCH3)OH) can lose H+ to form the ortho-methoxyphenoxide ion. The methoxy group (OCH3) is a +M group, which also destabilizes the negative charge. Therefore, ortho-methoxyphenol is less acidic than phenol.

### Conclusion:
Based on the analysis:
- Ethanol is less acidic than phenol.
- Ortho-nitrophenol is more acidic than phenol.
- Ortho-methylphenol is less acidic than phenol.
- Ortho-methoxyphenol is less acidic than phenol.

Thus, **phenol is less acidic than ortho-nitrophenol** but more acidic than ethanol, ortho-methylphenol, and ortho-methoxyphenol.

### Final Answer:
Phenol is less acidic than **ortho-nitrophenol**.