Write the chemical equation for the synthesis of aspirin and salicylic acid and acetic anhydride. Include all necessary reagents, catalysts, and reaction conditions.
Use H3PO4 as the catalysts.
The Correct Answer and Explanation is :
Chemical Equation for the Synthesis of Aspirin:
[
\text{C}7\text{H}_6\text{O}_3 + \text{(CH}_3\text{CO})_2\text{O} \xrightarrow{\text{H}_3\text{PO}_4} \text{C}_9\text{H}{8}\text{O}_4 + \text{CH}_3\text{COOH}
]
Explanation:
The synthesis of aspirin (acetylsalicylic acid) involves the esterification of salicylic acid ((\text{C}_7\text{H}_6\text{O}_3)) with acetic anhydride ((\text{(CH}_3\text{CO})_2\text{O})) in the presence of phosphoric acid ((\text{H}_3\text{PO}_4)) as a catalyst.
- Starting Materials:
- Salicylic Acid ((\text{C}_7\text{H}_6\text{O}_3)): This compound contains both a hydroxyl (-OH) and a carboxyl (-COOH) functional group.
- Acetic Anhydride ((\text{(CH}_3\text{CO})_2\text{O})): This reagent serves as an acetylating agent, donating an acetyl (-COCH₃) group to salicylic acid.
- Catalyst and Reaction Conditions:
- Phosphoric Acid ((\text{H}_3\text{PO}_4)): This acts as an acid catalyst, increasing the rate of reaction by protonating the carbonyl oxygen in acetic anhydride, making it more electrophilic.
- Reaction Temperature: Typically, the reaction is conducted at about 70-80°C for 10-20 minutes.
- Mechanism:
- The hydroxyl (-OH) group of salicylic acid attacks the electrophilic carbonyl carbon of acetic anhydride.
- This leads to the formation of an intermediate, which then loses a molecule of acetic acid ((\text{CH}3\text{COOH})), resulting in the formation of aspirin ((\text{C}_9\text{H}{8}\text{O}_4)).
- Purification:
- The reaction mixture is typically cooled, and water is added to hydrolyze any remaining acetic anhydride.
- The crude aspirin is filtered, washed, and purified by recrystallization using ethanol or water.
Conclusion:
This reaction is an example of esterification, where the hydroxyl group (-OH) of salicylic acid is replaced by an acetyl (-COCH₃) group from acetic anhydride, yielding aspirin and acetic acid. This process is widely used in the pharmaceutical industry for producing aspirin on a large scale.
Now, I will generate an image illustrating the reaction.
Here is the generated chemical reaction diagram for the synthesis of aspirin, showing the molecular structures, catalyst, and reaction conditions. Let me know if you need any modifications or further explanations!
