Which of the following compounds contain active methylene group ?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds contain an active methylene group, we need to identify the structures and analyze the presence of electron-withdrawing groups that can make the methylene hydrogens acidic. An active methylene group is a methylene (-CH2-) group that is adjacent to two electron-withdrawing groups, which increases the acidity of the hydrogens.

### Step-by-Step Solution:

1. **Identify the Compounds**:
We need to look at the structures of the compounds provided in the question. Let's denote them as A, B, C, and D.

2. **Analyze Compound A**:
- Structure: Contains two carbonyl groups (C=O) on either side of a methylene group (-CH2-).
- Analysis: The carbonyl groups are strong electron-withdrawing groups. The methylene group is between these two groups, making the hydrogens on this methylene acidic.
- Conclusion: Compound A contains an active methylene group.

3. **Analyze Compound B**:
- Structure: Similar to Compound A, it has a methylene group flanked by two carbonyl groups.
- Analysis: Again, the two carbonyl groups withdraw electron density, making the methylene hydrogens acidic.
- Conclusion: Compound B also contains an active methylene group.

4. **Analyze Compound C**:
- Structure: Contains a methylene group adjacent to two cyano groups (C≡N).
- Analysis: The cyano groups are also strong electron-withdrawing groups. The presence of two cyano groups makes the methylene hydrogens acidic.
- Conclusion: Compound C contains an active methylene group.

5. **Analyze Compound D**:
- Structure: Contains a methylene group adjacent to only one carbonyl group.
- Analysis: Since there is only one electron-withdrawing group, the methylene hydrogens are not sufficiently acidic to be considered an active methylene group.
- Conclusion: Compound D does not contain an active methylene group.

6. **Final Conclusion**:
- Compounds A, B, and C contain active methylene groups, while Compound D does not.

### Summary of Results:
- **Active Methylene Group Present**: A, B, C
- **Active Methylene Group Absent**: D