Which of the following compound will undergo tautomerism?

Options

A.
B.
C.
D.

Answer

To determine which of the given compounds will undergo tautomerism, we need to understand the concept of tautomerism itself. Tautomerism is a type of isomerism where structural isomers (tautomers) readily interconvert, typically involving the relocation of a proton (H⁺) and a shift of a double bond.

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- Look at the compounds provided and identify the functional groups present in each. Tautomerism usually occurs in compounds with carbonyl groups (C=O) and adjacent alpha hydrogens.

2. **Check for Alpha Hydrogens**:
- An alpha hydrogen is a hydrogen atom attached to the carbon adjacent to a functional group (like a carbonyl). For tautomerism to occur, the compound must have at least one alpha hydrogen.

3. **Analyze Each Compound**:
- **Compound 1**: Check for the presence of alpha hydrogens. If it has them, it can undergo tautomerism.
- **Compound 2**: Similarly, check for alpha hydrogens. If none are present, it cannot undergo tautomerism.
- **Compound 3**: Again, check for alpha hydrogens. If there are none, it cannot undergo tautomerism.
- **Compound 4**: Check for alpha hydrogens. If it has alpha hydrogens, it can undergo tautomerism.

4. **Determine Tautomeric Forms**:
- For the compound that has alpha hydrogens, illustrate how the tautomerism occurs. This typically involves the migration of an alpha hydrogen to the oxygen atom, forming an enol form from a keto form or vice versa.

5. **Conclusion**:
- After analyzing all compounds, identify which compound(s) can undergo tautomerism based on the presence of alpha hydrogens.

### Example Analysis:
- **Compound 1**: Contains alpha hydrogens → Can undergo tautomerism.
- **Compound 2**: No alpha hydrogens → Cannot undergo tautomerism.
- **Compound 3**: No alpha hydrogens → Cannot undergo tautomerism.
- **Compound 4**: Contains alpha hydrogens → Can undergo tautomerism.

### Final Answer:
The compound that will undergo tautomerism is the one with alpha hydrogens.