Which one is incorrect name ?

Options

A. Propyne
B. But-2-yne
C. Pent-3-yne
D. But-1-yne

Explanation

To determine which name is incorrect among the options provided, we need to analyze the names and their corresponding structures based on IUPAC nomenclature rules for hydrocarbons.

### Step-by-Step Solution:

1. **Identify the Structures of the Given Names**:
- **Propane**: The structure of propane is CH3-CH2-CH3, which is a three-carbon alkane. The name is correct.
- **But-2-yne**: The structure of but-2-yne is CH3-C≡C-CH3. This indicates a triple bond between the second and third carbon atoms in a four-carbon chain. The name is correct.
- **Pent-3-yne**: The structure of pent-3-yne is CH3-CH2-C≡C-CH3. This indicates a triple bond between the third and fourth carbon atoms in a five-carbon chain. The name is correct.
- **But-1-yne**: The structure of but-1-yne is CH≡C-CH2-CH3. This indicates a triple bond between the first and second carbon atoms in a four-carbon chain. The name is correct.

2. **Check for Incorrect Naming**:
- The name **Pent-3-yne** is indeed correct as it follows the IUPAC rules for naming hydrocarbons with a triple bond.
- The name **But-1-yne** is also correct as it accurately describes the structure of the compound.

3. **Conclusion**:
- The only name that is incorrectly stated in the context of the question is **Pent-3-yne**, which should not exist as a valid name for the structure described. The correct name would be **But-2-yne** for a four-carbon compound with a triple bond.

### Final Answer:
The incorrect name among the options is **Pent-3-yne**.

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