Which of the given below is best method of preparing alkyl chloride?

Options

A. `ROH +SOCl_(2)`
B. `ROH+PCl_(5)rarr`
C. `ROH +PCl_(3)rarr`
D. `ROH+HCl overset("anhy. ZnCl"_(2))rarr`

Answer

To determine the best method for preparing alkyl chloride from the given options, we will analyze each method step by step.

### Step-by-Step Solution:

1. **Understanding Alkyl Chloride Formation**:
Alkyl chlorides can be prepared from alcohols using various reagents. The general reaction involves replacing the hydroxyl group (-OH) of the alcohol with a chlorine atom (Cl).

2. **Option A: Alcohol + SOCl2**:
- Reaction: R-OH + SOCl2 → R-Cl + SO2 + HCl
- Here, sulfur dichloride (SOCl2) reacts with the alcohol to produce alkyl chloride (R-Cl), sulfur dioxide (SO2), and hydrogen chloride (HCl).
- Both SO2 and HCl are gases, which can be easily removed from the reaction mixture.

3. **Option B: Alcohol + PCl5**:
- Reaction: R-OH + PCl5 → R-Cl + POCl3 + HCl
- In this case, phosphorus pentachloride (PCl5) reacts with the alcohol to yield alkyl chloride, phosphorus oxychloride (POCl3), and HCl.
- HCl is a gas, but POCl3 is a liquid, which may complicate the separation process.

4. **Option C: Alcohol + PCl3**:
- Reaction: R-OH + PCl3 → R-Cl + H3PO3
- Here, phosphorus trichloride (PCl3) reacts with the alcohol to form alkyl chloride and phosphorous acid (H3PO3).
- H3PO3 is a liquid, making it less favorable for easy separation.

5. **Option D: Alcohol + HCl (in presence of anhydrous conditions)**:
- Reaction: R-OH + HCl → R-Cl + H2O
- This method uses hydrochloric acid directly, but it typically requires anhydrous conditions to be effective. The byproduct, water (H2O), is a liquid, which complicates separation.

6. **Conclusion**:
- Among the options, **Option A (Alcohol + SOCl2)** is the best method for preparing alkyl chloride because it produces gaseous byproducts (SO2 and HCl) that can be easily removed from the reaction mixture, facilitating a cleaner and more efficient reaction.

### Final Answer:
The best method of preparing alkyl chloride is **Option A: Alcohol + SOCl2**.