Question

Question:

a. Ketoprofen, like ibuprofen, is an anti- inflammatory analgesic. How can ketoprofen be synthesized from the given starting material?

ketoprofen

b. ketoprofen and ibuprofen both have a propanoic acid substituent. Explain why the identical subunits are synthesized in different ways.

Short answer

The answer is,

a.

Reaction

b. The deactivated benzene rings cannot undergo Friedel- Crafts reaction.

Step-by-step solution

Friedel- Crafts acylation

The Friedel- Crafts acylation reaction is the reaction of alkyl compounds with acyl compounds in presence of catalyst to give acyl compounds. The acyl group is introduced to the compound undergoing reaction.

Subpart (a)

The reaction for the synthesis of ketoprofen is as given below.

Reaction

Subpart (b)

The substituent in ibuprofen is placed on the ring by a Friedel- Crafts acylation reaction. A Friedel- Crafts reaction cannot be done in the synthesis of ketoprofen, because the benzene rings are deactivated and deactivated rings cannot undergo Friedel- Crafts reactions.