Which alkyne will give 3-ethylhexane on catalytic hydrogenation?

Options

A.
B.
C.
D. All of these

Explanation

To determine which alkyne will yield 3-ethylhexane upon catalytic hydrogenation, we can follow these steps:

### Step 1: Understand the structure of 3-ethylhexane
3-ethylhexane is a six-carbon chain (hexane) with an ethyl group (C2H5) attached to the third carbon. The structure can be represented as follows:
- Main chain: CH3-CH2-CH(CH2CH3)-CH2-CH2-CH3

### Step 2: Identify the alkyne that can produce this structure
To produce 3-ethylhexane through catalytic hydrogenation, we need to consider the structure of the alkyne that can be reduced to this alkane.

### Step 3: Consider possible alkynes
1. **Alkyne A**: 3-ethyl-1-butyne (CH3-C≡C-CH2-CH2-CH3)
- When hydrogenated, it will yield 3-ethylhexane.

2. **Alkyne B**: 2-butyne (CH3-C≡C-CH3)
- This alkyne will not yield 3-ethylhexane upon hydrogenation.

3. **Alkyne C**: 1-heptyne (CH3-C≡C-CH2-CH2-CH2-CH3)
- This alkyne will yield 3-ethylhexane upon hydrogenation.

### Step 4: Verify the hydrogenation process
When we perform catalytic hydrogenation on the identified alkynes:
- **For Alkyne A**:
- The triple bond is reduced to a double bond, and then to a single bond, resulting in 3-ethylhexane.

- **For Alkyne C**:
- The triple bond is also reduced similarly, leading to the same product.

### Conclusion
Both Alkyne A (3-ethyl-1-butyne) and Alkyne C (1-heptyne) will yield 3-ethylhexane upon catalytic hydrogenation. Therefore, the answer is that both A and C are correct.

### Final Answer
Alkynes A and C will give 3-ethylhexane on catalytic hydrogenation.

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