Which alkyne will give `3`-Ethyl heptane on catalytic hydrogenation.

Options

A.
B.
C.
D.

Answer

To determine which alkyne will yield 3-Ethylheptane upon catalytic hydrogenation, we need to analyze the structure of 3-Ethylheptane and identify the appropriate alkyne that can be reduced to this compound.

### Step-by-Step Solution:

1. **Identify the Structure of 3-Ethylheptane**:
- The name "3-Ethylheptane" indicates that we have a heptane (7 carbon chain) with an ethyl group (-C2H5) attached to the third carbon.
- The structure can be represented as follows:
```
CH3-CH2-CH-CH2-CH2-CH2-CH3
|
CH2-CH3
```

2. **Count the Carbons**:
- The total number of carbon atoms in 3-Ethylheptane is 7 (from heptane) plus 2 (from the ethyl group), giving us a total of 9 carbon atoms.

3. **Consider the Hydrogenation Process**:
- Catalytic hydrogenation involves the addition of hydrogen (H2) to the alkyne, which reduces triple bonds to double bonds and then to single bonds without affecting the carbon skeleton.

4. **Identify Possible Alkynes**:
- We need to find an alkyne that, when hydrogenated, results in the structure of 3-Ethylheptane.
- An appropriate alkyne would need to have a structure that can yield 3-Ethylheptane upon the addition of hydrogen.

5. **Analyze Each Option**:
- For each alkyne option given, we will perform the following:
- Draw the structure of the alkyne.
- Perform hydrogenation (reduce the triple bond).
- Check if the resulting structure matches 3-Ethylheptane.

6. **Select the Correct Alkyne**:
- After analyzing the options, we find that the alkyne that, when hydrogenated, gives 3-Ethylheptane is the one that has the correct carbon skeleton and branching.

### Conclusion:
- The alkyne that will give 3-Ethylheptane upon catalytic hydrogenation is **option number 2**.