Which of the following phenols is most soluble in aqueous sodium bicarbonate?

Options

A. `2,4`-dihydroxyacetophenone
B. `p`-cyanophenol
C. `3,4`-dicyanophenol
D. `2,4,6`-trichyanophenol

Answer

To determine which phenol is most soluble in aqueous sodium bicarbonate, we need to analyze the structures of the given phenols and their ability to react with sodium bicarbonate (NaHCO3).

### Step-by-Step Solution:

1. **Understanding the Reaction**: Sodium bicarbonate is a weak base and can react with acidic compounds. Phenols can act as weak acids due to the presence of the hydroxyl (-OH) group. When a phenol reacts with sodium bicarbonate, it can form a phenolate ion, which is soluble in water.

2. **Identify the Phenols**: We need to look at the structures of the phenols provided in the options. The question specifically mentions 2,4,6-tri-sino-phenol (which is likely a typo and should refer to 2,4,6-trinitrophenol).

3. **Analyzing 2,4,6-Trinitrophenol**: The structure of 2,4,6-trinitrophenol has three nitro (-NO2) groups attached to the benzene ring. These nitro groups are electron-withdrawing and increase the acidity of the phenolic -OH group. This means that 2,4,6-trinitrophenol will be more likely to lose a proton (H+) and form a phenolate ion when reacted with sodium bicarbonate.

4. **Solubility in Aqueous Sodium Bicarbonate**: The formation of the phenolate ion enhances the solubility of the compound in water. Since 2,4,6-trinitrophenol can easily form a phenolate ion, it will be the most soluble in aqueous sodium bicarbonate compared to other phenols which may not have such strong electron-withdrawing groups.

5. **Conclusion**: Therefore, the phenol that is most soluble in aqueous sodium bicarbonate is 2,4,6-trinitrophenol (option D).

### Final Answer:
**The phenol that is most soluble in aqueous sodium bicarbonate is 2,4,6-trinitrophenol.**

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