Acetic acid can be converted into acetic anhydride on heating

Options

A. `POCl_(3)`
B. `PCl_(3)`
C. `PCl_(5)`
D. `P_(2)O_(5)`

Answer

To convert acetic acid (ethanoic acid) into acetic anhydride through heating, we need to follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactant is acetic acid, which has the chemical formula \( \text{CH}_3\text{COOH} \).

2. **Understand the Product**:
- The product we want to form is acetic anhydride, which has the chemical structure \( \text{(CH}_3\text{CO)}_2\text{O} \) or can be represented as \( \text{CH}_3\text{C(=O)O(C=O)CH}_3 \).

3. **Reaction Mechanism**:
- The conversion involves the removal of a water molecule from two molecules of acetic acid. This can be represented as:
\[ 2 \text{CH}_3\text{COOH} \rightarrow \text{(CH}_3\text{CO)}_2\text{O} + \text{H}_2\text{O} \]

4. **Choosing a Dehydrating Agent**:
- To facilitate the removal of water, a dehydrating agent is required. Among the options provided (POCl3, PCl3, PCl5, P2O5), P2O5 is a well-known dehydrating agent that effectively removes water from the reaction mixture.

5. **Final Reaction**:
- When acetic acid is heated with P2O5, it leads to the formation of acetic anhydride by removing water:
\[ 2 \text{CH}_3\text{COOH} + \text{P}_2\text{O}_5 \rightarrow \text{(CH}_3\text{CO)}_2\text{O} + \text{H}_2\text{O} + \text{P}_2\text{O}_4 \]

6. **Conclusion**:
- Therefore, the correct dehydrating agent that converts acetic acid into acetic anhydride upon heating is \( \text{P}_2\text{O}_5 \).