Which of the following compounds does not have diastereomers?

Options

A. But`-2-`ene
B. Butane`-2,3-`diol
C. `2,3-`Dibromopentane
D. Butan`-2-ol`

Explanation

To determine which of the given compounds does not have diastereomers, we need to understand the concept of stereoisomers, particularly focusing on diastereomers and chiral centers.

### Step-by-Step Solution:

1. **Understanding Stereoisomers**:
- Stereoisomers are compounds that have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of atoms.
- There are two main types of stereoisomers: enantiomers (non-superposable mirror images) and diastereomers (not mirror images).

2. **Identifying Chiral Centers**:
- A chiral center (or chiral carbon) is a carbon atom that is attached to four different groups. The presence of chiral centers is essential for the existence of diastereomers.
- To have diastereomers, a compound must have at least two chiral centers.

3. **Analyzing the Given Compounds**:
- **Butyrene**: This compound does not have any chiral centers. Therefore, it cannot have diastereomers.
- **2,3-Butanediol**: This compound has two chiral centers, which means it can have diastereomers.
- **2,3-Dibromobutane**: This compound also has two chiral centers, allowing for the possibility of diastereomers.
- **Butan-2-ol**: This compound has only one chiral center, so it cannot have diastereomers.

4. **Conclusion**:
- Among the options analyzed, **Butyrene** is the compound that does not have diastereomers because it lacks chiral centers.

### Final Answer:
The compound that does not have diastereomers is **Butyrene**.