Acetylferrocene is an organoiron compound with a two-carbon acetyl group attached to one of its cyclopentadienyl rings. It is an orange, air-stable solid that is soluble in organic solvents. The discovery of ferrocene in 1951 spawned the transition metal based organometallic chemistry field, which has yielded a great diversity of molecules in which saturated, unsaturated, and aromatic organic fragments are directly bonded to transition metal centers.
The symmetrical arrangement of the ferrocene molecule in its pure form makes it very strong and leads to the formation of a crystal lattice. However, the acetyl group disrupts this symmetry and weakens bonds. This explains why acetylferrocene has a lower melting point than pure ferrocene.
Traditionally, acetylferrocene is synthesized by a classical Friedel-Crafts acylation reaction using dichloromethane or carbon disulfide as the solvent. A Lewis acid (such as aluminum chloride or hydrogen fluoride) or a Bronsted acid such as polyphosphoric acid is used as the catalyst. The acylation is then followed by deprotonation with t-BuLi/t-BuOK in THF at 0 degC to generate the corresponding disubstituted ferrocene. This is converted to a monosubstituted ferrocene by Kagan-Sharpless epoxidation with methyl ketone and lithiation with triisopropylphenyllithium in THF, to give 2-formyl-1-chlorovinylferrocene (398).
The Thermo Scientific Chemicals brand of acetylferrocene was previously sold under the Alfa Aesar product portfolio. Documentation and labeling for the legacy product may still be available.