4. Which one of the following compounds does not given `C_(2)H_(5)`Cl by the reaction of `C_(2)H_(5)`OH?

Options

A. `SOCl_(2)`
B. `PCl_(5)`
C. `ZnCl_(2) + ` HCl
D. `Cl_(2)`

Answer

To solve the question of which compound does not give C2H5Cl (ethyl chloride) when reacted with C2H5OH (ethanol), we will analyze the reactions of various compounds with ethanol.

### Step-by-Step Solution:

1. **Identify the Compounds**: We need to consider the four compounds mentioned in the question. Let's denote them as A, B, C, and D for simplicity.

2. **Reaction with SOCl2**:
- When ethanol (C2H5OH) reacts with thionyl chloride (SOCl2), it produces ethyl chloride (C2H5Cl) along with by-products (SO2 and HCl).
- **Conclusion**: This compound (let's say A) gives C2H5Cl.

3. **Reaction with PCl5**:
- Similarly, when ethanol reacts with phosphorus pentachloride (PCl5), it also produces ethyl chloride (C2H5Cl) along with POCl3 and HCl.
- **Conclusion**: This compound (let's say B) also gives C2H5Cl.

4. **Reaction with ZnCl2**:
- When ethanol reacts with zinc chloride (ZnCl2), it forms a complex. The ZnCl2 acts as a Lewis acid and facilitates the formation of a carbocation (C2H5+). The chloride ion (Cl-) then attacks this carbocation, leading to the formation of ethyl chloride (C2H5Cl).
- **Conclusion**: This compound (let's say C) also gives C2H5Cl.

5. **Reaction with Cl2**:
- When ethanol (C2H5OH) is treated with chlorine gas (Cl2), the hydroxyl group (OH) is not a good leaving group. Although Cl2 can react with alcohols, the OH group will not leave easily to form a carbocation. Thus, the reaction will not proceed to form ethyl chloride (C2H5Cl).
- **Conclusion**: This compound (let's say D) does not give C2H5Cl.

6. **Final Answer**: Therefore, the compound that does not give C2H5Cl by the reaction with C2H5OH is the one that reacts with Cl2.