The product of the reaction of ethyne with hydrochloric acid can also be prepared by the following reaction:

Options

A. Ethanal with ` "PCl"_(5)`
B. Ethene with `Cl_(2)`
C. Ethyl chloride with `Cl_(2)`
D. None of the above

Answer

To solve the question regarding the product of the reaction of ethyne with hydrochloric acid and its alternative preparation, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
The reactants are ethyne (C2H2) and hydrochloric acid (HCl).

2. **Understand the Reaction Type**:
The reaction between ethyne and HCl is an addition reaction. This is typical for alkenes and alkynes where the double or triple bond reacts with a reagent.

3. **Apply Markovnikov's Rule**:
In the absence of peroxides, the addition of HCl to alkynes follows Markovnikov's rule. This means that the halide (Cl) will attach to the carbon with fewer hydrogen atoms.

4. **Draw the Structure of Ethyne**:
Ethyne has the structure H-C≡C-H.

5. **Add HCl to Ethyne**:
When HCl is added to ethyne, the triple bond breaks and forms a double bond. The Cl will attach to the carbon with fewer hydrogen atoms.

6. **Formation of the Intermediate**:
The addition of HCl can lead to the formation of an intermediate:
- The first addition gives CH2=CHCl (vinyl chloride).

7. **Further Addition of HCl**:
Adding HCl again to the vinyl chloride will lead to the formation of the final product:
- CH3-CHCl2 (1,1-dichloroethane).

8. **Identify Alternative Preparation**:
The question mentions that the product can also be prepared through another reaction. One such reaction is the chlorination of ethanol (C2H5OH) with phosphorus pentachloride (PCl5).

9. **Reaction of Ethanol with PCl5**:
When ethanol reacts with PCl5, the hydroxyl group (-OH) is replaced by chlorine, leading to the formation of 1,1-dichloroethane (CH3-CHCl2).

10. **Conclusion**:
The product of the reaction of ethyne with hydrochloric acid (CH3-CHCl2) can also be obtained by the reaction of ethanol with PCl5.

### Final Answer:
The product of the reaction of ethyne with hydrochloric acid (CH3-CHCl2) can also be prepared by the reaction of ethanol with phosphorus pentachloride (PCl5).

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