I use carboxylic ferrocene (Fc-COOH) and react with acetic anhydride in H3PO4. Hopefully I can get acetylation on the Cp ring without COOH. But from H NMR, it seems that I got 100% of acetylation on the ring where COOH is...?? How is electrophilic addition happened on a Cp ring with electron withdrawing group??
As Vladimir said, it almost certainly reacts to form the mixed anhydride first.
It might be worthwhile to protect the carboxylic acid as an ester first, then treat with acetic anhydride in the presence of a strong lewis acid (like AlCl3) in an anhydrous solvent, like dcm. The reaction should should proceed at room temperature within a few hours, and be selective for the unsubsituted ring.
As Vladimir said, it almost certainly reacts to form the mixed anhydride first.
It might be worthwhile to protect the carboxylic acid as an ester first, then treat with acetic anhydride in the presence of a strong lewis acid (like AlCl3) in an anhydrous solvent, like dcm. The reaction should should proceed at room temperature within a few hours, and be selective for the unsubsituted ring.
- Badges
- Science topic
- Similar topics
- Chemistry
- Organic Chemistry