Which of the following compounds will give a mixture of 1 - chlorobutane & 2 - chlorobutane on free radical chlorination ?

Options

A. `(CH_(3))_(2)CH- CH = CH_(2)`
B. `CH_(3) - CH_(2) - CH_(2) - CH_(3)`
C. `CH_(2) = CH - CH = CH_(2)`
D. None of the above

Answer

To determine which compound will give a mixture of 1-chlorobutane and 2-chlorobutane upon free radical chlorination, we need to analyze the possible candidates based on their structure and the mechanism of free radical chlorination.

### Step-by-Step Solution:

1. **Understanding Free Radical Chlorination**:
- Free radical chlorination involves the substitution of hydrogen atoms in alkanes with chlorine atoms. The process occurs in three steps: initiation, propagation, and termination.
- The key point is that the stability of the radical intermediate influences the product distribution. More stable radicals will form preferentially.

2. **Identifying the Compounds**:
- We need to consider the structural formulas of the given compounds. The compounds should ideally have both primary (1°) and secondary (2°) hydrogens to yield both 1-chlorobutane and 2-chlorobutane.

3. **Analyzing the First Compound**:
- If the first compound is a straight-chain alkane like butane (C4H10), chlorination will predominantly yield 1-chlorobutane due to the presence of only primary hydrogens.

4. **Analyzing the Second Compound**:
- If the second compound is 2-methylbutane (C5H12), it has both primary and secondary hydrogens. Chlorination of this compound will yield a mixture of 1-chlorobutane and 2-chlorobutane:
- The chlorine radical can attack the primary carbon (yielding 1-chlorobutane) or the secondary carbon (yielding 2-chlorobutane).

5. **Analyzing the Third Compound**:
- If the third compound is symmetrical (like 2,2-dimethylpropane), chlorination will yield only one type of product, as all the hydrogens are equivalent.

6. **Analyzing the Fourth Compound**:
- If the fourth compound is a cyclic compound or has a double bond, the chlorination will not yield both products due to the lack of sufficient primary and secondary hydrogens.

7. **Conclusion**:
- The compound that will yield a mixture of 1-chlorobutane and 2-chlorobutane upon free radical chlorination is the one that contains both primary and secondary hydrogens, which is 2-methylbutane (the second option).

### Final Answer:
The compound that will give a mixture of 1-chlorobutane and 2-chlorobutane upon free radical chlorination is **2-methylbutane**.

---