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    For the reaction between salicylic acid, acetic anhydride and conc sulfuric acid, the phenol group undergoes esterification to produce aspirin.

    Questions:

    - why is the phenol group esterified, not the carboxylic acid group? Bc the carboxylic acid group has a lower pKa so should surely be a more acidic group and therefore be better able to donate e-s to the ch3co+ group?

    - why would the given conditions not lead to aromatic substitution? They do for benzene, and s.acid has both an EWG and an EDG so should be approx. same reactivity as benzene? (aspirin less reactive than s. acid bc EDG is weaker, so subs of aspirin less likely)

    Any help would be much appreciated!
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    (Original post by pippabethan)
    For the reaction between salicylic acid, acetic anhydride and conc sulfuric acid, the phenol group undergoes esterification to produce aspirin.

    Questions:

    - why is the phenol group esterified, not the carboxylic acid group? Bc the carboxylic acid group has a lower pKa so should surely be a more acidic group and therefore be better able to donate e-s to the ch3co+ group?
    Ethanoic anhydride reacts with the OH groups of alcohols and phenols forming esters. It is an acid anhydride and will not react with a carboxylic acid group.

    - why would the given conditions not lead to aromatic substitution? They do for benzene, and s.acid has both an EWG and an EDG so should be approx. same reactivity as benzene? (aspirin less reactive than s. acid bc EDG is weaker, so subs of aspirin less likely)

    Any help would be much appreciated!
    Ethanoic anhydride with sulfuric acid produces a nucleophilic intermediate species, which will not react with the electron rich aromatic ring.
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    (Original post by charco)
    Ethanoic anhydride reacts with the OH groups of alcohols and phenols forming esters. It is an acid anhydride and will not react with a carboxylic acid group.


    Ethanoic anhydride with sulfuric acid produces a nucleophilic intermediate species, which will not react with the electron rich aromatic ring.
    Thanks so much for your reply!
    I was just wondering why the cooh didn't react; surely the oh in cooh could act in a similar way so that -cooh --> -coococh3
    Also, I thought that the int. was ch3co+ which is electrophilic?
 
 
 
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