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) by the reaction with C2H5OH (ethanol), we can analyze the options provided.

### Step-by-Step Solution:

1. **Identify the Reactant**: The reactant is ethanol, which has the formula C2H5OH.

2. **Analyze the First Option (Thionyl Chloride, SOCl2)**:
- When ethanol reacts with thionyl chloride, the chloride ion (Cl-) acts as a nucleophile and substitutes the hydroxyl group (OH) in ethanol.
- The reaction produces C2H5Cl (ethyl chloride), along with gaseous SO2 and HCl.
- Therefore, this option does give C2H5Cl.

3. **Analyze the Second Option (Phosphorus Pentachloride, PCl5)**:
- When ethanol reacts with PCl5, it also results in the formation of C2H5Cl, along with POCl3 and HCl.
- Thus, this option also gives C2H5Cl.

4. **Analyze the Third Option (Lucas Reagent, ZnCl2 + HCl)**:
- The Lucas reagent is used to distinguish between alcohols based on their reactivity.
- For primary alcohols like ethanol, there is no immediate reaction with the Lucas reagent. However, ethanol can still react under certain conditions.
- In the presence of ZnCl2, ethanol can form a complex, and the OH group can be replaced by Cl, leading to the formation of C2H5Cl.
- Therefore, this option also gives C2H5Cl.

5. **Analyze the Fourth Option (Chlorine, Cl2)**:
- Chlorine can oxidize ethanol. When ethanol (a primary alcohol) is oxidized, it converts to acetaldehyde (CH3CHO).
- The chlorination of acetaldehyde does not lead to the formation of C2H5Cl directly. Instead, it may lead to chlorinated products of the aldehyde.
- Therefore, this option does not yield C2H5Cl.

### Conclusion:
The compound that does not give C2H5Cl by the reaction with C2H5OH is **Chlorine (Cl2)**.

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