Why wouldn't this form an EAS product as well?

[BMEEngineer]

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Both the halogen with carbonyl and the carboxylic acid are meta directors, so I don't know why it doesn't form that product as well as the anhydride.

Thank you!

http://imgur.com/HYM8rIi

 

[tandem7]

The nucleophile (the oxygen on the carboxylic acid) would much rather react with the carbonyl adjacent to the acyl chloride than any part of the benzene ring. Also, the chlorine is a great leaving group and stable on its own. Therefore, the energy to make the anhydride product is substantially lower than the energy you would need to make an aromatic substitution, so no aromatic substitution on either ring would occur, so you would not even have to assess whether they are ortho/para or meta directing substituents.

 

[BMEEngineer]

I guess I'm having a hard time with the distinction "substantially lower energy." Why isn't the EAS product made, but just in much smaller quantities than the anhydride? Is it because the activation energy can't be overcome? How would I recognize other situations like this, just look for really good leaving groups?

 

[MrSummerlin]

pyridine a weak base is being used as the reagent. This reagent will take the H fro the carboxylic acid making that O- very nucleophilic cause the reaction to produce the anyhydride. A benzene ring is not very reactive so you need to review the reagents used to have a meta ,ortho... addition

 

[BMEEngineer]

Thank you! I will go back and review those solvents/reagents.