Alkyl halides are prepared from alcohols by treating with

Options

A. `HCl+ZnCl_(2)`
B. Red P+`Br_(2)`
C. `H_(2)SO_(4)`+Kl
D. All of these

Explanation

To prepare alkyl halides from alcohols, we can use specific reagents. Let's analyze the options provided in the question step by step.

### Step 1: Understanding the Reaction
Alkyl halides (R-X) can be synthesized from alcohols (R-OH) through substitution reactions. In this process, the hydroxyl group (-OH) of the alcohol is replaced by a halogen (X).

### Step 2: Evaluating the Options
1. **Option A: HCl and ZnCl2**
- When alcohol (R-OH) is treated with HCl in the presence of ZnCl2, a substitution reaction occurs, leading to the formation of alkyl chloride (R-Cl).
- This method is known as the Lucas reagent method.
- **Conclusion**: This option is correct.

2. **Option B: Red phosphorus and Br2**
- When alcohol (R-OH) is treated with red phosphorus and bromine (Br2), the alcohol undergoes a reaction to form alkyl bromide (R-Br).
- This is another valid method for synthesizing alkyl halides.
- **Conclusion**: This option is also correct.

3. **Option C: H2SO4 and KI**
- When KI is treated with H2SO4, the sulfuric acid oxidizes KI to iodine (I2) rather than forming HI, which would be necessary for the formation of alkyl iodide (R-I).
- Therefore, this method does not yield alkyl halides.
- **Conclusion**: This option is incorrect.

4. **Option D: Not applicable**
- Since option C is incorrect, option D cannot be correct either.

### Final Conclusion
The correct reagents for preparing alkyl halides from alcohols are:
- **Option A: HCl and ZnCl2**
- **Option B: Red phosphorus and Br2**

### Summary of the Solution
- Alkyl halides can be prepared from alcohols using:
- HCl and ZnCl2 (Lucas reagent) → forms alkyl chloride (R-Cl).
- Red phosphorus and Br2 → forms alkyl bromide (R-Br).
- H2SO4 and KI do not yield alkyl halides.