Which of the following compound can give only one monochlorinated product upon free radical chlorination?

Options

A. 2-Methylpropane
B. n-Butane
C. 2, 2-Dimethylpropane
D. 2, 3 dimethylpentane

Answer

To determine which compound can give only one monochlorinated product upon free radical chlorination, we need to analyze the structures of the given compounds and their symmetry. Here’s a step-by-step solution:

### Step 1: Understand Free Radical Chlorination
Free radical chlorination involves the reaction of alkanes with chlorine (Cl2) in the presence of UV light, leading to the formation of free radicals. The chlorine radicals can abstract hydrogen atoms from the alkane, resulting in the formation of alkyl halides.

### Step 2: Analyze Each Compound
1. **2-Methylpropane (C5H12)**:
- Structure:
```
CH3
|
CH3-C-CH2-CH3
|
CH3
```
- Chlorination can occur at any of the three equivalent CH3 groups or the CH2 group, leading to multiple products. Therefore, it can give more than one monochlorinated product.

2. **n-Butane (C4H10)**:
- Structure:
```
CH3-CH2-CH2-CH3
```
- Chlorination can occur at the terminal CH3 or at the CH2 groups, leading to two different products. Thus, it can also give more than one monochlorinated product.

3. **2,2-Dimethylpropane (C5H12)**:
- Structure:
```
CH3
|
CH3-C-CH3
|
CH3
```
- All the CH3 groups are equivalent, and chlorination will yield only one unique product regardless of which hydrogen is replaced. Thus, it gives only one monochlorinated product.

4. **2,3-Dimethylpentane (C7H16)**:
- Structure:
```
CH3
|
CH3-CH-CH-CH2-CH3
|
CH3
```
- This compound has different environments for hydrogen atoms, leading to multiple possible products. Therefore, it can give more than one monochlorinated product.

### Step 3: Conclusion
From the analysis, **2,2-Dimethylpropane** is the only compound that can give only one monochlorinated product upon free radical chlorination.

### Final Answer:
**2,2-Dimethylpropane** is the compound that gives only one monochlorinated product.

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