Friedel-Crafts reaction is an electrophilic aromatic substitution reaction in which an electrophile replaces a hydrogen atom in an aromatic compound forming a new carbon-carbon bond. This breed of reactions were discovered by Charles Friedel and James Crafts in 1877 and are thus are now known as Friedel-Crafts reactions. The reactions can be used in the commencement of either alkyl and acyl groups; the acyl group being the key contender in the acetylation of ferrocene.
In the acylation of ferrocene (also known as a "sandwich" compound, rings being the starchy bread and iron being the beefy meat patty) reaction a strong Lewis acid, most generally aluminum chloride, is required which yields a generous amount of inimical waste. Also, the commonly used solvents such as a carbon disulfide or dichloromethane, present hazards to both the environment and humans. In continuation with the theme of Green Chemistry, phosphoric acid and acetic anhydride are used as reagents and in turn generating a more salubrious product. It was possible to use acetic anhydride as the catalyst in the reaction due to the higher reactivity of a metallocene (“sandwich” compound) versus a benzene ring.
The addition of phosphoric acid to the mixture transformed the color into a burnt umber color.
When poured over ice, solution turned phthalo green hue.
When stirred, solution returned to a rust color.
The final product melted cleanly, and did not decompose.
Melting Point
Onset: 80.7°C
Clear Point: 81.4°C
Chromatography
R: Reagents
C: Crude Product
P: Final Product
Analysis
Melting point analysis
The documented melting point of Acetylferrocene is between 81°C-86°C. The observed melting point of the final crystals being at that range shows that the product was very pure. Narrow melting range supports this assertion.
Chromatography analysis
The Thin layer Chromatography was performed with the original, crude, and final products. The components of the mixture can be assessed and separated using this method; finding either purity, identifying compounds, or checking the progress of the reaction, in this case it was to assess the purity of the final product. The capillary action of the plate coating carried the three solvents solutes! up the height of the plate. Certain solvents travelled certain distances and one can see by the farthest right stain that there is little of the reagent left towards the top of the stain, which leads to the conclusion that the final product was relatively pure. ...but not absolutely. I see as many as 4 separated compounds in your final product. Interesting, isn't it, that these show up on the TLC when they don't influence the melting point in such a way as to make you think it's impure?
Name: Acetylferrocene
IUPAC Name: Acetylferrocene
CAS #: 1271-55-2
Molecular Formula:C₁₂H₁₂FeO
Structure:
Conclusion/Discussion
One of the main potential areas for error in this procedure could possibly be attributed to the transfer processes throughout the reaction. There were numerous relocations of the mixture for the duration of the experiment and this seems to perhaps be factor for a lower yield. After the NaOH addition the sodium bicarbonate was added to the mixture. This could have also proved a reason for error as larger quantities of sodium bicarbonate were added than desired, creating excessive foaming.
During the hot filtration aspect of the procedure formation of crystals were seen on the upper portions of the filter paper. This could have also lead to reduced yields as not all of the desired product made it into the receiving beaker. A significant sample of the crude product was also removed for TLC analysis, lowering the yield even more.
Friedel-Crafts acylation gives fundamentally the same product that an alkylation would. However, in a Friedel-Crafts acylation the product does not undergo further rearrangement of the electrophile nor is it susceptible to supplemental reactions. The metallocene is more reactive with electrophilic reagents thus permitting a more suitable reaction.
The procedure also follows protocol for the green chemistry standards by nixing the use of the unsafe reagents and catalysts and in turn the generation of hazardous organic solvents. These reasons make the Friedel-Crafts acylation procedure far more desirable for use in the green chemistry fields.
This report earned the following scores for: format (2/2) style (2/2) data (3/3) quality of result (1/1) quality of reported data (1/1) conclusion (2/2) error (1/1) for a total of 14. I would give you extra points for using "inimical" and "salubrious" correctly in your report, but unfortunately you have already pegged out at the top of the scoring range.
Post Lab Question
Q: Find and write two additional Friedel-Crafts acylation reactions. (Acylation not alklation)
Reactions on a Solid Surface. A Simple, Economical and Efficient Friedel-Crafts Acylation Reaction over Zinc Oxide (ZnO) as a New Catalyst. M. H. Sarvari, H. Sharghi, J. Org. Chem., 2004, 69, 6953-6956.
Mild, Efficient Friedel-Crafts Acylations from Carboxylic Acids Using Cyanuric Chloride and AlCl3. C. O. Kangani, B. W. Day, Org. Lett., 2008, 10, 2645-2648.
Introduction
Friedel-Crafts reaction is an electrophilic aromatic substitution reaction in which an electrophile replaces a hydrogen atom in an aromatic compound forming a new carbon-carbon bond. This breed of reactions were discovered by Charles Friedel and James Crafts in 1877 and are thus are now known as Friedel-Crafts reactions. The reactions can be used in the commencement of either alkyl and acyl groups; the acyl group being the key contender in the acetylation of ferrocene.
In the acylation of ferrocene (also known as a "sandwich" compound, rings being the starchy bread and iron being the beefy meat patty) reaction a strong Lewis acid, most generally aluminum chloride, is required which yields a generous amount of inimical waste. Also, the commonly used solvents such as a carbon disulfide or dichloromethane, present hazards to both the environment and humans. In continuation with the theme of Green Chemistry, phosphoric acid and acetic anhydride are used as reagents and in turn generating a more salubrious product. It was possible to use acetic anhydride as the catalyst in the reaction due to the higher reactivity of a metallocene (“sandwich” compound) versus a benzene ring.
Procedure
The lab procedure for this experiment can be found at University of Oregon's Greener Education Materials for Chemists.
The chemicals used for this lab are as follows:
Data
Analysis
Conclusion/Discussion
One of the main potential areas for error in this procedure could possibly be attributed to the transfer processes throughout the reaction. There were numerous relocations of the mixture for the duration of the experiment and this seems to perhaps be factor for a lower yield. After the NaOH addition the sodium bicarbonate was added to the mixture. This could have also proved a reason for error as larger quantities of sodium bicarbonate were added than desired, creating excessive foaming.
During the hot filtration aspect of the procedure formation of crystals were seen on the upper portions of the filter paper. This could have also lead to reduced yields as not all of the desired product made it into the receiving beaker. A significant sample of the crude product was also removed for TLC analysis, lowering the yield even more.
Friedel-Crafts acylation gives fundamentally the same product that an alkylation would. However, in a Friedel-Crafts acylation the product does not undergo further rearrangement of the electrophile nor is it susceptible to supplemental reactions. The metallocene is more reactive with electrophilic reagents thus permitting a more suitable reaction.
The procedure also follows protocol for the green chemistry standards by nixing the use of the unsafe reagents and catalysts and in turn the generation of hazardous organic solvents. These reasons make the Friedel-Crafts acylation procedure far more desirable for use in the green chemistry fields.
This report earned the following scores for: format (2/2) style (2/2) data (3/3) quality of result (1/1) quality of reported data (1/1) conclusion (2/2) error (1/1) for a total of 14. I would give you extra points for using "inimical" and "salubrious" correctly in your report, but unfortunately you have already pegged out at the top of the scoring range.
Post Lab Question
Q: Find and write two additional Friedel-Crafts acylation reactions. (Acylation not alklation)
A: The following two reactions were obtained from the website ( http://www.organic-chemistry.org/namedreactions/friedel-crafts-acylation.shtm ) with citations for each reaction directly below:
Notes
The chemical structures, formulas, and vital statistics of each compound was researched using Wolfram Alpha computational knowledge engine and confirmed using the CRC Handbook of Chemistry and Physics [90th Edition].