Phenol is less acidic than

Options

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

Explanation

To determine which compound phenol is less acidic than, we need to analyze the acidity of phenol in comparison to the given compounds: ethanol, ortho-nitrophenol, ortho-methyl phenol, and ortho-methoxy phenol.

### Step-by-Step Solution:

1. **Understanding Phenol's Acidity**:
- Phenol (C6H5OH) has a hydroxyl (-OH) group attached to a benzene ring. The acidity of phenol is due to the ability of the -OH group to donate a proton (H+), forming a phenoxide ion (C6H5O-).

2. **Comparing with Ethanol**:
- Ethanol (C2H5OH) has a similar -OH group but is less acidic than phenol. This is because the ethyl group (C2H5) is an electron-donating group (due to the +I effect), which increases the electron density on the oxygen atom, making it less likely to lose a proton compared to phenol.
- **Conclusion**: Phenol is more acidic than ethanol.

3. **Comparing with Ortho-Nitrophenol**:
- Ortho-nitrophenol has a nitro group (-NO2) at the ortho position. The nitro group is a strong electron-withdrawing group (due to -I and -R effects), which stabilizes the negative charge on the phenoxide ion formed after deprotonation.
- **Conclusion**: Ortho-nitrophenol is more acidic than phenol.

4. **Comparing with Ortho-Methyl Phenol**:
- Ortho-methyl phenol has a methyl group (-CH3) at the ortho position. The methyl group is an electron-donating group (due to +I effect), which increases the electron density on the oxygen atom, making it less acidic than phenol.
- **Conclusion**: Ortho-methyl phenol is less acidic than phenol.

5. **Comparing with Ortho-Methoxy Phenol**:
- Ortho-methoxy phenol has a methoxy group (-OCH3) at the ortho position. The methoxy group is also an electron-donating group (due to +I effect), which increases the electron density on the oxygen atom, making it less acidic than phenol.
- **Conclusion**: Ortho-methoxy phenol is less acidic than phenol.

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