The reagent used to get alkyl halide from alcohol is

Options

A. `PCl_5`
B. `SOCl_2`
C. both 1 & 2
D. `Cl_2`

Explanation

To convert an alcohol into an alkyl halide, we can use several reagents. Here’s a step-by-step solution to identify the reagent used for this conversion:

### Step 1: Identify the Functional Groups
- Alcohols contain a hydroxyl group (-OH) which is responsible for their properties. Alkyl halides, on the other hand, contain a halogen atom (X) bonded to an alkyl group (R-X).

### Step 2: Understand the Reaction Mechanism
- The conversion of alcohols to alkyl halides typically involves the substitution of the hydroxyl group (-OH) with a halogen atom (like Cl, Br, or I).

### Step 3: Choose a Suitable Reagent
- Common reagents used for this conversion include:
- Phosphorus trichloride (PCl3)
- Phosphorus pentachloride (PCl5)
- Thionyl chloride (SOCl2)
- Hydrochloric acid (HCl) in the presence of zinc chloride (ZnCl2)

### Step 4: Example Reaction with PCl5
1. When an alcohol reacts with phosphorus pentachloride (PCl5), the lone pair of electrons on the oxygen atom of the alcohol attacks the phosphorus atom.
2. This leads to the formation of an intermediate where the -OH group is replaced by a chlorine atom.
3. The reaction can be summarized as:
\[ R-OH + PCl_5 \rightarrow R-Cl + POCl_3 + HCl \]
Here, R represents the alkyl group.

### Step 5: Conclusion
- Therefore, one of the reagents that can be used to convert alcohols to alkyl halides is phosphorus pentachloride (PCl5).