Acetaldehyde reacts with `PCl_(5)` to give :

Options

A. ethyl chloride
B. ethylene chloride
C. ethylidene dichloride
D. trichloroacetaldehyde

Explanation

To solve the question of what acetaldehyde reacts with PCl5 to produce, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are acetaldehyde (CH3CHO) and phosphorus pentachloride (PCl5).

### Step 2: Understand the Reaction Mechanism
When acetaldehyde reacts with PCl5, it undergoes a substitution reaction. PCl5 is a chlorinating agent that can replace the hydroxyl (–OH) group in the carbonyl compound (acetaldehyde) with chlorine atoms.

### Step 3: Draw the Structure of Acetaldehyde
Acetaldehyde has the structure:
```
O
||
CH3-C-H
```

### Step 4: Reaction with PCl5
In the presence of PCl5, the carbonyl oxygen (C=O) will be replaced by chlorine atoms. The reaction can be summarized as follows:
1. The double bond between carbon and oxygen is broken.
2. The oxygen forms POCl3 as a byproduct.
3. Two chlorine atoms will attach to the carbon atom.

### Step 5: Write the Product Structure
The product formed will be:
```
Cl
|
CH3-C-Cl
```
This compound is known as ethylidene dichloride.

### Step 6: Name the Product
The IUPAC name of the product is ethylidene dichloride.

### Conclusion
When acetaldehyde reacts with PCl5, it produces ethylidene dichloride.

### Final Answer
The correct answer is ethylidene dichloride.

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