Acetylation+of+Ferrocene

=Acetylation of Ferrocene~=

**__Introduction:__**
Acetylation of Ferrocene is a process, known as a Friedel-Crafts reaction, in which a new carbon-carbon bond is created through an electrophilic aromatic substitution. Acetylation is when an acetyl group is added to a chemical compound. Many components such as phosphoric acid, NaOH, and hexanes are added to ferrocene to achieve the final product of an acetylation reaction. The acetylation that is performed in this experiment is of the following reaction: As shown in the reaction, the acetyl group (C-C-C=O) is added to the ferrocene molecule which is the process of acetylation.

__Procedure:__
The procedure for this experiment is found here:

http://greenchem.uoregon.edu/PDFs/GEMsID72.pdf

__Additional Procedure:__
Do not use steam baths. Instead use hot water bath. No drying tube necessary in the assembly. Step 7: Heat gently; do not boil or product will be lost. (don't boil or the hexanes will boil away and you won't be able to proceed)

__Data:__
Formula of ferrocene: C10H10Fe Molecular Weight ferrocene: 186.04 g/mol Melting Point (lit value): 174 degrees celsius Ferrocene: 1.576 g Acetic Anhydride: 5.0 mL 85% Phosphoric Acid: 1.0 mL Ice: 24.969 g Ice Water: 2 - 5.0 mL portions 3 M NaOH Solution: 37.5 mL ~6 g NaHCO3 Weight of Crude Product: 5.662 g Portion of Crude Product Used: 1.856 g Norit Pellets: 1 spatula full Hexanes: 20 mL Acetylferrocene Product: 0.099 g Assessed Melting Point of Acetylferrocene: 80.8-82.1 degrees celsius Formula of Acetylferrocene: C12H12FeO Molecular Weight Acetylferrocene: 228.07 g/mol Melting Point (lit value): 81-86 degrees celsius







__Note:__
Due to the high crude product yield, a 1.856 g portion was separated and used to complete the rest of the procedure. This amount of crude product is easier to work with. Because of this, a percent yield and a percent recovery are given. Thanks for doing the calculations in the way that I asked. Your crude product yield includes a significant amount of water, clearly. The percent yield analyzes the ratio between the starting material, ferrocene, and the crude product. The percent recovery analyzes the ratio between the crude product and the final product, acetylferrocene. It reports the amount of final product that was obtained from the processing of the 1.856 g of crude product.

The above three photo were taken during step 4. The result was a black colored substance that began to thicken.

The above two pictures were taken during steps 5/6.

Crude Product Collected

The Final Product Collected

TLC From Left to Right Lane 1 (Ferrocene,yellow), Lane 2 (Crude Product, Orange), Lane 3 (Final Product, Orange) Nice TLC: but just as a technical point, I'd wait to photograph the plates until the solvent dries away. It makes the colors stand out a bit more against the white silica background.

Conclusion:
The acetylation of ferrocene is a process in which an acetyl group is substituted for a Hydrogen on a benzene ring of ferrocene. In order for this process to be complete many impurities are added, which shows up in the mass of crude product being much higher than that of the starting material. Two to three filtrations are required to remove impurities in the final product of acetylferrocene.There was a percent yield of 5.3%. This would normally be a low percent, however, only a small portion of the intermediate crude product underwent the final filtration process. If all the crude product was used then it can be assumed the percent yield would have increased as well.

According the TLC (imaged above) the final product was relatively pure. Lane 1 shows the movement of the substance to the top of the testing strip, this is the movement of ferrocene. Lane 2, the crude product, shows that some unreacted ferrocene remained. Finally, Lane 3 shows the final purified product. Based on this lane the product was pure as no yellow spot is lined up with the original ferrocene indicating most of the substance has been reacted.

The melting point range of the final product was within a couple degrees of the literature value. This is another indication that the substance was fairly pure. Having a melting point close to the lit value sort of suggests purity.....but more information on purity comes from the melting point range. Tell me what the range of melting temps says about your product.

According to the data above, this process of acetylation has a lot of waste involved. The overall product being achieved is only a small fraction of materials required to complete the reaction, which makes the reaction appear rather environmentally unfriendly.

Possible Sources of Error:
Sources of error include the possible use of too much sodium bicarbonate to neutralize the acidic solution before filtration of the crude product leading to higher mass and more impurity in the crude product. Some final purified product remained crystallized to the sides of the erlenmeyer flask leading to slightly smaller recovery.

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 (1.5/2) error (1/1) post-lab Q (2/2) for a total of 13.5/14. Nice job.

Post Lab Question:
2 additional Friedal Crafts Acylation Reactions:





Post-Lab Sources: http://www.mhhe.com/physsci/chemistry/carey/student/olc/ch12friedelcraftsacylation.html http://dept.lamar.edu/chemistry/martincb/CHEM3412/CHEM%203412%20Lab%20-%20Friedel-Crafts.pdf