Free radical chlorination of hexane produces how many of monochloro derivatives? (including stereoisomer)

Options

A. 5
B. 7
C. 8
D. 3

Answer

To determine how many monochloro derivatives can be produced from the free radical chlorination of hexane, we will follow these steps:

### Step 1: Identify the Structure of Hexane
Hexane is a straight-chain alkane with the formula C6H14. Its structure can be represented as:
\[ \text{CH}_3-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_3 \]

### Step 2: Identify Equivalent Carbons
In hexane, we have:
- 2 equivalent carbons at the ends (C1 and C6)
- 2 equivalent carbons in the middle (C2 and C5)
- 2 equivalent carbons in the middle (C3 and C4)

This gives us three distinct types of hydrogen atoms that can be replaced by chlorine:
1. Primary (C1 and C6)
2. Secondary (C2 and C5)
3. Tertiary (C3 and C4)

### Step 3: Determine the Number of Structural Isomers
When chlorination occurs, we can replace one hydrogen atom with a chlorine atom at each of these equivalent positions:
- Replacing a hydrogen from C1 or C6 gives us one type of monochloro derivative.
- Replacing a hydrogen from C2 or C5 gives us another type of monochloro derivative.
- Replacing a hydrogen from C3 or C4 gives us a third type of monochloro derivative.

Thus, we have three different structural isomers:
1. 1-chlorohexane (from C1 or C6)
2. 2-chlorohexane (from C2 or C5)
3. 3-chlorohexane (from C3 or C4)

### Step 4: Identify Chiral Centers
Next, we need to check for chiral centers among these isomers:
- **1-chlorohexane**: No chiral center.
- **2-chlorohexane**: Has one chiral center (C2), leading to two optical isomers (R and S).
- **3-chlorohexane**: Has one chiral center (C3), leading to two optical isomers (R and S).

### Step 5: Count Total Monochloro Derivatives
Now, we can summarize the total number of monochloro derivatives:
- Structural isomers: 3 (1-chlorohexane, 2-chlorohexane, 3-chlorohexane)
- Optical isomers:
- 2 for 2-chlorohexane (R and S)
- 2 for 3-chlorohexane (R and S)

Thus, the total number of monochloro derivatives is:
\[ 1 \text{ (from 1-chloro)} + 2 \text{ (from 2-chloro)} + 2 \text{ (from 3-chloro)} = 5 \]

### Final Answer
The total number of monochloro derivatives of hexane, including stereoisomers, is **5**.

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