Which reaction is termed as Darzen's reaction ?

Options

A. ROH + HCI
B. `ROH + PCI_(5)`
C. `ROH+SOCl_(2)`
D. `ROH+PCl_(3)`

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about a specific reaction known as Darzen's reaction. It's important to identify the correct reaction among the given options.

2. **Identifying the Options**:
- Option 1: ROH + HCl
- Option 2: ROH + PCl5
- Option 3: ROH + SOCl2
- Option 4: ROH + PCl3

3. **Analyzing Each Option**:
- **Option 1**: ROH + HCl - This reaction involves the conversion of alcohol to alkyl chloride but is not specifically known as Darzen's reaction.
- **Option 2**: ROH + PCl5 - This reaction also converts alcohol to alkyl chloride and produces POCl3 and HCl. It follows an SN2 mechanism but is not termed Darzen's reaction.
- **Option 3**: ROH + SOCl2 - This reaction is known for converting alcohols to alkyl chlorides with the formation of SO2 and HCl as byproducts. This reaction is often referred to as the "Darzen's reaction" or "Darzens reaction".
- **Option 4**: ROH + PCl3 - This reaction also converts alcohol to alkyl chloride but is not termed Darzen's reaction.

4. **Conclusion**: The reaction that is termed as Darzen's reaction is the one where an alcohol reacts with thionyl chloride (SOCl2), which is Option 3: ROH + SOCl2.

**Final Answer**: The reaction termed as Darzen's reaction is **ROH + SOCl2**.

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