Manufacture of Aspirin (AQA A Level Chemistry): Revision Note

Manufacture of Aspirin

Manufacture of Aspirin

• Acylation reactions are widely used in industry, including in the pharmaceutical industry to manufacture drugs such as aspirin, and in the textile industry to produce materials such as cellulose acetate.

• In the industrial manufacture of aspirin, salicylic acid reacts with ethanoic anhydride in an acylation reaction to form aspirin (acetylsalicylic acid) and ethanoic acid:

salicylic acid + ethanoic anhydride → aspirin + ethanoic acid

• Acyl chlorides can also undergo acylation reactions

  • When they react with water, a carboxylic acid and hydrogen chloride are formed

  • When they react with alcohols, esters and hydrogen chloride are produced.

• However, reactions involving acyl chlorides are usually fast and highly exothermic, producing corrosive hydrogen chloride gas

• For this reason, acid anhydrides are preferred in the manufacture of aspirin

  • They are generally less reactive, easier to control, and cheaper to produce

  • In addition, the by-product formed is a carboxylic acid, which is less hazardous than hydrogen chloride