Which reagent will produce salicyldehyde on reaction with phenol?

Explanation

To determine which reagent will produce salicylaldehyde from phenol, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction Type**: The reaction that converts phenol to salicylaldehyde is known as the Reimer-Tiemann reaction. This reaction is specifically used for ortho-formylation of phenols.

**Hint**: Look for reactions that involve the ortho-position of phenolic compounds.

2. **Reagents Required**: The Reimer-Tiemann reaction requires chloroform (CHCl3) and a strong base, typically sodium hydroxide (NaOH), as the reagents.

**Hint**: Remember that strong bases are often used in reactions that involve the formation of aldehydes from phenolic compounds.

3. **Reaction Conditions**: The reaction is carried out at elevated temperatures, usually around 340 Kelvin. This helps in facilitating the reaction between phenol and chloroform in the presence of NaOH.

**Hint**: Temperature can significantly affect the outcome of chemical reactions, especially in organic synthesis.

4. **Mechanism Overview**:
- The phenol reacts with chloroform in the presence of NaOH, leading to the formation of an intermediate compound.
- This intermediate undergoes rearrangement and loss of water to yield salicylaldehyde.

**Hint**: Understanding the mechanism can help in predicting the products formed in organic reactions.

5. **Final Product**: After the reaction and subsequent work-up (which may include acidification), the final product obtained is salicylaldehyde (C6H4(OH)CHO).

**Hint**: Always verify the structure of the final product to ensure that the desired compound has been synthesized.

### Conclusion:
The reagents that will produce salicylaldehyde from phenol are chloroform (CHCl3) and sodium hydroxide (NaOH) under the conditions of the Reimer-Tiemann reaction.