Acetylation of ferrocene. An Introduction to the Synthesis and Reactions of Ferrocene 2022-10-15
Acetylation of ferrocene
Ferrocene is a metallocene compound that consists of two cyclopentadienyl rings bonded to a central iron atom. It is an aromatic compound that exhibits high stability and is widely used in various fields, including catalysis, materials science, and medicine. One important method of modifying the properties of ferrocene is through acetylation, which is the addition of an acetyl group (-COCH3) to the compound.
Acetylation of ferrocene can be carried out using various methods, such as chemical acetylation and biological acetylation. In chemical acetylation, ferrocene is reacted with acetic anhydride or acetyl chloride in the presence of a strong acid catalyst, such as sulfuric acid or hydrochloric acid. This reaction results in the replacement of one or both of the cyclopentadienyl rings with acetyl groups, forming monoacetylated or diacetylated ferrocene, respectively.
Biological acetylation of ferrocene can be carried out using enzymes, such as acetyltransferases. This method allows for the selective acetylation of specific positions on the ferrocene molecule, as different enzymes have specific substrate preferences. For example, N-acetyltransferases can acetylate the nitrogen atoms in ferrocene, while lysine acetyltransferases can acetylate the lysine residues in ferrocene-containing peptides.
The acetylation of ferrocene has significant effects on the properties of the compound. Acetylation can increase the solubility of ferrocene in polar solvents, as the acetyl groups introduce additional polar functionalities to the molecule. In addition, acetylation can affect the electronic properties of ferrocene, as the acetyl groups can donate or withdraw electron density from the central iron atom. This can lead to changes in the reactivity and catalytic activity of ferrocene.
Overall, acetylation of ferrocene is a useful method for modifying the properties of this compound and has numerous applications in various fields. Further research on the acetylation of ferrocene is ongoing and has the potential to lead to the development of new materials and catalysts with improved properties.
Practical Experiment 6: Friedel Crafts Acetylation Of Ferrocene
Discussion: When comparing the Rf values obtained from the thin layer chromatography trial, it can be concluded that the hexane fraction Rf of 0 contained ferrocene Rf of 0 and the dichloromethane fraction Rf of 0 contained acetylferrocene Rf of 0. Then the conjugate base produced from the protonation of acetic anhydride removes a hydrogen atom to restore the aromaticity of the cyclopentadienyl ring forming the final product acetylferrocene. This reagent forms colored precipitates or reaction products with many cations, including all of those used in this experiment. It follows the same two general mechanistic steps of EAS: electrophilic attack on an aromatic ring to generate a high energy organic cation intermediate followed by aromatization. Fall 2013 Organic Chemistry Laboratory Manual; P.
Acetic acid reacts with phosphoric acid to produce acetic acid and the acylium ion Step 2 Once the acylium ion is generated, it goes on to react with one of the carbon atoms of a cyclopentadienyl ring, which gives us our acetylated ferrocene product. Reactions: Overall Reaction Acetylation of Ferrocene Pictures taken from U. Relying on DFT calculations and analysis of spin-density distribution combined with paramagnetic NMR data a chelating coordination of the CpBTZ ligand is feasible in 12. Abstract: The purpose of the experiment is to learn electrophilic aromatic substitution reaction, learn that electrophiles replace hydrogen atoms in aromatic compounds forming new bonds, determine percentage yield, atom economy, and the melting point. The identifications of ferrocene and diacetylferrocene can also be confirmed conceptually. The iron is in its bivalent form, since treatment of a carbon tetrachloride solution of the material with bromine in the same solvent gave a blue solution containing ferrous and bromide ions. Side reactions of acetylation that produce byproducts exist and are discussed in Appendix A.
09B Acetylation of Ferrocene
The mixture was left to stand for an hour with stirring before the crude product was collected with vacuum filtration. An acetyl group When ferrocene undergoes an acetylation reaction, the acetyl group attaches to one of the cyclopentadienyl rings by substituting one hydrogen atom on one of the cyclopentadienyl rings. The paper was then put into a beaker of a hydrochloric acid, ethanol, and butanol mixture, being sure that the paper does not touch the sides of the beaker, and then topped. If you did have unreacted ferrocene, then there will be two mass spectra. The aqueous layer is collected in a beaker and made up to 50mL with water. A small chromatographic column was constructed and the sample was dissolved in a minimal amount of dichloromethane.
Acetylation of Ferrocene Experiment
Ferrocene is an organometallic compound made of iron, carbon, and hydrogen that's considered the prototypical metallocene. Palladium typically exists in the oxidation states of 0, +2, and +4. Perhaps you're old-school and go for the tried-and-true peanut butter and jelly, or maybe you're more of the saucy type and really enjoy a good meatball-marinara sub. Hence there is equal bonding of all the carbon atoms in the cyclopentadienyl rings to the central Fe 2+ ion. Example of an acetyl group In order to add an acetyl group to ferrocene, all we need to do is react it with acetic anhydride the source of the acetyl group and some phosphoric acid. It is important to remember that if a chemical is mixed with a differing chemical, the melting point is decreased drastically, but if it is mixed with a component very similar in chemical make up, the melting point will not differ much from the expected.
Acetylation of Ferrocene
An example of the Friedel-Crafts Acylation Reaction is shown by the acylation of benzene with acetyl chloride, catalyzed by aluminum trichloride, shown below. The cyclopentadienyl anion contains five carbon atoms and a negative charge that is delocalized across the entire ring system In order to make ferrocene, iron is reacted with excess of the cyclopentadienyl anion and what comes out is ferrocene. Ferrocene is sometimes referred to as a sandwich compound because it belongs to the subclass of organometallic compounds called metallocenes which are a group of compounds that contains a metallic central atom bound between two cyclopentadienyl rings that resembles a sandwich. Often the boiling point of a substance is above the temperature at which the compound would start to decompose. University of Virginia, 2013 When acetylferrocene is heated for too long, a second acetylation occurs. Step 2 In the second step, the acylium ion that was generated will react with one of the carbon atoms on the cyclopentadienyl ring.
(PDF) The Synthesis and Acetylation of Ferrocene
Arenes, for instance benzene, are more susceptible to attack by electrophiles than nucleophiles. TLC was performed with the two fractions and ferrocene, acetylferrocene, and diacetylferrocene standards and the Rf values were compared in order to identify the components. Occasionally remove the flask from the water bath and swirl to mix the reaction. Ligand exchange of ferrocene with benzene Figure 8. The new chromium III complex CpBTZCrCl2 12 becomes upon activation an active catalyst for the polymerization of ethylene.
An Introduction to the Synthesis and Reactions of Ferrocene
Avoid skin contact, ingestion, and inhalation. Ferrocene, C 5 H 5 2 Fe, was first discovered in 1951. No color remained in the column and so no acetone fraction was collected. If you did not have any unreacted ferrocene in your product, then you will only have one significant peak in the gas chromatogram and one corresponding mass spectrum to analyze. Each solution was transferred to tared round-bottom flasks and the solvent was evaporated.
Acylation of ferrocene: a new approach
Both contain 5 carbons and two conjugated π bonds. Rinse the reaction flask with small volumes of ice water until transfer is complete. Talmage Procedure: In this lab we mixed many different substances to see if they formed a double replacement reaction. Only transport these liquids in closed containers. The unusual nature of ferrocene and the cyclopentadienyl anions that it contains can be seen clearly by comparing cyclopentadiene to 1,3-pentadiene. A 3D image of a ferrocene molecule.