Give a alternative method of synthesis of aspirin using salicylic acid as the starting materials. Give the mechanism

Answer 1

One alternative method of synthesizing aspirin from salicylic acid involves using acetic anhydride as the acetylating agent in the presence of sulfuric acid as a catalyst. The mechanism for this reaction is as follows:

1. The sulfuric acid protonates the carbonyl oxygen of acetic anhydride, making it more electrophilic.

2. The protonated acetic anhydride attacks the phenolic oxygen of salicylic acid, forming a tetrahedral intermediate.

3. The tetrahedral intermediate collapses, kicking out a molecule of acetic acid and forming the aspirin product.

4. Finally, the sulfuric acid deprotonates the acetylated product to give aspirin and regenerate the catalyst.

This method is commonly used on an industrial scale to produce aspirin due to its high yield and efficiency.