Question

There are three and only three possible diacetylferrocenes. Draw their stuctures

a) what does the number of isomers indicate about the relative orientation of two cyclopentadienyl rings?

b) whic diacetyl isomers would be expected from friedel-crafts acetylation of ferrocene??

In synthesis and acetylation of ferrocene.?

Answer 1

The Friedel-Crafts acylation of benzene derivatives requires aluminum chloride, a strong Lewis acid, as a catalyst. In contrast, Ferrocene, react under milder conditions, with acetic anhydride and phosphoric acid as the catalyst. Ferrocene has pronounced aromaticity from the typical benzene derivatives.Since acylation reactions put a deactivating group on an aromatic ring, and the risk of getting di- or poly-acylated products should be minimal, but some diacetylferrocene might be formed.

in the isomers the isomer (II) will be formed on the course of diacetylation.The deactivating acetyl decreases the electron density of the first cyclopentadienyl group and thus the other acetyl group goes to the other cyclopentadienyl group.