Number of chiral centers in chloramphenicol is :

Answer

To determine the number of chiral centers in chloramphenicol, we need to analyze its structure and identify the carbon atoms that are bonded to four different substituents. Here is a step-by-step solution:

### Step 1: Understand the Structure of Chloramphenicol
Chloramphenicol has a specific chemical structure that includes several functional groups. The key components include:
- A nitro group (NO2)
- A phenyl ring
- Hydroxyl groups (OH)
- An amide linkage (NH-C=O)
- A dichloro group (Cl2)

### Step 2: Identify the Carbon Atoms
In chloramphenicol, we need to identify the carbon atoms that could potentially be chiral centers. A chiral center is typically a carbon atom that is bonded to four different groups.

### Step 3: Analyze Each Carbon Atom
1. **First Carbon (attached to the phenyl ring)**:
- This carbon is attached to:
- A phenyl group
- A CH2OH group
- A hydrogen atom
- An OH group
- Since all four substituents are different, this carbon is a chiral center.

2. **Second Carbon (attached to the CH2OH)**:
- This carbon is attached to:
- A CH2OH group
- An amide linkage (NH-C=O)
- An OH group
- A hydrogen atom
- Again, all four substituents are different, making this carbon another chiral center.

3. **Third Carbon (attached to the amide linkage)**:
- This carbon is attached to:
- An NH group
- A C=O group
- Two Cl atoms
- Since it has two identical chlorine atoms, this carbon cannot be a chiral center.

4. **Other Carbons**:
- Any other carbon atoms in the structure either have identical substituents or do not have four different groups attached.

### Step 4: Count the Chiral Centers
From the analysis, we have identified two chiral centers in chloramphenicol.

### Final Answer
The number of chiral centers in chloramphenicol is **2**.

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