Which of the following compounds would liberate two moles of methane when treated with methyl magnesium bromide ?

Options

A. `CH_3-undersetunderset(OH)(|)CH-CH_2-C=CH`
B. `CH_3-undersetunderset(O)(||)C-CH_2-CH_2OH`
C. `CH_3-undersetunderset(O)(||)C-oversetoverset(CH_3)(|)CH-undersetunderset(O)(||)C -CH_3`
D.

Explanation

To solve the question of which compound would liberate two moles of methane when treated with methyl magnesium bromide (CH3MgBr), we will analyze each compound step by step.

### Step-by-Step Solution:

1. **Understanding Methyl Magnesium Bromide (CH3MgBr)**:
- Methyl magnesium bromide is a Grignard reagent. The methyl group (CH3-) acts as a strong nucleophile and base, capable of deprotonating acidic hydrogens.

2. **Identifying Acidic Hydrogens**:
- We need to identify which of the given compounds has two acidic hydrogens that can be removed by CH3-.

3. **Analyzing the First Compound**:
- The first compound contains a hydroxyl group (OH) and a carbon-carbon triple bond (C≡C).
- The hydrogen from the OH group is acidic and can be removed by CH3-.
- The hydrogen from the terminal alkyne (C≡C) is also acidic and can be removed by CH3-.
- Therefore, this compound can liberate 2 moles of methane (one from OH and one from the terminal alkyne).

4. **Analyzing the Second Compound**:
- This compound has only one acidic hydrogen that can be removed. Thus, it will liberate only 1 mole of methane.

5. **Analyzing the Third Compound**:
- Similar to the second compound, this compound also has only one acidic hydrogen. Therefore, it will liberate only 1 mole of methane.

6. **Analyzing the Fourth Compound**:
- This compound also has only one acidic hydrogen that can be removed. Hence, it will liberate only 1 mole of methane.

7. **Conclusion**:
- Only the first compound can liberate 2 moles of methane when treated with methyl magnesium bromide. The other compounds can only liberate 1 mole of methane each.

### Final Answer:
The compound that would liberate two moles of methane when treated with methyl magnesium bromide is **option 1**.