In the Darzen’s process for the preparation of alkyl chlorides, alcohols react with:

Options

A. Thionyl chloride in pyridine
B. Sulphuryl chloride in pyridine
C. HCl + anlny. `ZnCl_(2)`
D. None of the above

Answer

**Step-by-Step Solution:**

1. **Understanding the Darzen’s Process**: The Darzen’s process is a method used to prepare alkyl chlorides from alcohols. In this process, alcohols react with thionyl chloride (SOCl2) in the presence of a base, typically pyridine.

2. **Identifying the Reactants**: In the Darzen’s process, the alcohol (which contains the hydroxyl group -OH) reacts with thionyl chloride (SOCl2). The pyridine acts as a base to facilitate the reaction.

3. **Mechanism of the Reaction**:
- The hydroxyl group (-OH) of the alcohol has a lone pair of electrons that can attack the sulfur atom in thionyl chloride.
- This leads to the formation of an intermediate where the oxygen of the alcohol becomes positively charged (OH+).
- The chlorine atom in thionyl chloride is a good leaving group and will eventually leave, resulting in the formation of alkyl chloride.

4. **Formation of By-products**: During the reaction, sulfur dioxide (SO2) and hydrochloric acid (HCl) are produced as by-products. The overall reaction can be summarized as:
\[ \text{R-OH} + \text{SOCl}_2 \xrightarrow{\text{Pyridine}} \text{R-Cl} + \text{SO}_2 + \text{HCl} \]
where R represents the alkyl group.

5. **Conclusion**: Therefore, in the Darzen’s process for the preparation of alkyl chlorides, alcohols react with thionyl chloride (SOCl2) in the presence of pyridine.

**Final Answer**: Alcohols react with thionyl chloride (SOCl2) in the presence of pyridine to form alkyl chlorides.

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