`underset("Specific rotation" = +50^(@))(Ph-CH(OH)CH_(3)) overset(SOCl_(2))(rarr) underset(Cl)underset(|)(PhCH) - CH_(3)`
The reaction is carried out in the presence of pyridne, Which of the following mechanisms does it follow?

Options

A. `SN^(1)`
B. `SN^(2)`
C. `SN^(i)`
D. `E2`

Explanation

To determine the mechanism of the reaction where an alcohol is converted into a benzylic halide in the presence of pyridine, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants and Products**:
- The reactant is an alcohol (Ph-CH(OH)CH₃) and the product is a benzylic halide (Ph-CHCl-CH₃).
- The reaction involves the substitution of the hydroxyl group (-OH) with a chlorine atom (Cl).

2. **Understand the Role of Pyridine**:
- Pyridine is a heterocyclic aromatic compound that acts as a base in this reaction.
- It is also a polar aprotic solvent, which means it does not donate protons (H⁺) but can stabilize ions.

3. **Determine the Type of Reaction**:
- The substitution of -OH with Cl can occur through two main mechanisms: SN1 and SN2.
- SN1 involves a two-step process where the leaving group departs first, forming a carbocation intermediate, followed by nucleophilic attack.
- SN2 involves a single concerted step where the nucleophile attacks the substrate as the leaving group departs.

4. **Analyze the Solvent Effect**:
- Since pyridine is a polar aprotic solvent, it favors the SN2 mechanism.
- Polar aprotic solvents stabilize the nucleophile but do not stabilize carbocations, making SN1 less favorable.

5. **Conclusion**:
- Given that the reaction occurs in a polar aprotic solvent (pyridine), and involves a direct nucleophilic substitution, the mechanism followed in this reaction is SN2.

### Final Answer:
The mechanism followed in the reaction is **SN2**.

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