Intramolecular hydrogen bonding is found in `:`

Options

A. m-Hyroxy benzaldehyde
B. Salicylaldehye
C. Benzaldehyde
D. p-Hydroxy benzaldehyde

Answer

To determine which compound exhibits intramolecular hydrogen bonding, we will analyze the structures of the given options: metahydroxybenzaldehyde, salicylaldehyde, parahydroxybenzaldehyde, and benzaldehyde.

### Step-by-Step Solution:

1. **Understanding Intramolecular Hydrogen Bonding**:
- Intramolecular hydrogen bonding occurs when hydrogen bonding happens within the same molecule. This usually involves a hydrogen atom bonded to an electronegative atom (like oxygen) and another electronegative atom within the same molecule.

2. **Analyzing the Compounds**:
- **Metahydroxybenzaldehyde**:
- Structure: The hydroxyl (-OH) group is at the meta position relative to the aldehyde (-CHO) group.
- Analysis: The distance between -OH and -CHO is too far for intramolecular hydrogen bonding to occur. Therefore, this compound does not exhibit intramolecular hydrogen bonding.

- **Salicylaldehyde**:
- Structure: The hydroxyl (-OH) group is at the ortho position relative to the aldehyde (-CHO) group.
- Analysis: The -OH group can form a hydrogen bond with the carbonyl oxygen of the -CHO group because they are close enough in the same molecule. Thus, salicylaldehyde exhibits intramolecular hydrogen bonding.

- **Parahydroxybenzaldehyde**:
- Structure: The hydroxyl (-OH) group is at the para position relative to the aldehyde (-CHO) group.
- Analysis: Similar to metahydroxybenzaldehyde, the -OH and -CHO groups are too far apart to form intramolecular hydrogen bonds. Therefore, this compound does not exhibit intramolecular hydrogen bonding.

- **Benzaldehyde**:
- Structure: Benzaldehyde consists of a benzene ring with a single aldehyde (-CHO) group.
- Analysis: There is no hydroxyl group present, so there can be no hydrogen bonding, either intermolecular or intramolecular.

3. **Conclusion**:
- Based on the analysis, the only compound that exhibits intramolecular hydrogen bonding is **salicylaldehyde**.

### Final Answer:
The correct answer is **salicylaldehyde** (option B).

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