Why 4-aminophenol reacts with acetic anhydride to form an amide rather than an ester in the synthesis of paracetamol ? ?

I’m struggling with this question. Can someone help me with the question above. 

2 Answers

  • Mike A
    Lv 7
    2 months ago

    The amino group is the stronger nucleophile and reacts much more rapidly with the anhydride. If you use excess acetic anhydride both the amino and the hydroxyl groups can be acetylated but using the stochiometric quantity of reagent only the acetylated amine is formed. And no you can't form an ester by reacting a carboxylic acid with a phenol. Phenols are distinctly different to alcohols and do not react with carboxylic acids. To acylate a phenol an anhydride or an acid chloride is usually used.

  • 2 months ago

    Because making an ester requires an alcohol and a carboxylic acid.  In particular, the acid needs to have a -COOH group, but acetic anhydride does not have such a group so it cannot make an ester.  (If you really need the ester you could add some water to the anhydride and make acetic acid, which should do the job.)

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