Friedel—Crafts reaction Save The Friedel—Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in to attach substituents to an aromatic ring. Both proceed by electrophilic aromatic substitution.
Acetylation of Ferrocene Length: It proceeded via a Friedel-Crafts reaction without the use of organic solvents or strong Lewis acid.
Operations and Observations A mixture of ferrocene 1. The mixture was then refluxed with a calcium chloride drying tube for ten minutes and left to cool for an hour taking on a dark almost black colour.
The reaction mixture was then poured onto ice 60 mL and stirred to form brown mixture with some greenish black precipitate. Aqueous sodium hydroxide The mixture was left to stand for an hour with stirring before the crude product was collected with vacuum filtration.
The product was air dried for a couple of minutes then boiled with hexane 20 mL leaving behind a brown- black gummy substance.
The product was then decolourised with activated charcoal and recrystallized from hexane to give Sorry, but full essay samples are available only for registered users Choose a Membership Plan dark orange crystals 0.
A TLC plate was used to compare the ferrocene, the crude product and the recrystallised product. The ferrocene had an Rf value of approximately 0. Discussion There was a lot of the black insoluble material in the mixture and at times it appeared to be a slightly greenish colour in solution.
The greenish colour could be due to the presence of Fe II ions in the solution. If there were Fe II ions loose in the solution then the gummy substance could contain a cyclopentadienyl rings.
The properties that lead me to speculate this could be the substance is the density, which would be greater than exane, hence left at the bottom rather than floating on top and if it were acylated it would be a polar molecule hence its immiscibility in hexane.
The amount of the black substance may have been due to not quenching the mixture after heating. The low yield may also be attributed to the production of some diacteylferrocene, this may be the purple impurity observed and would have been separated from the acetylferrocene during the recrystallization as it is more polar and would have stayed in solution with the hexane.
The reaction also uses one of the reagents, acetic anhydride, as the solvent negating the need for organic solvents such as dichloromethane or carbon disulphide.
Acetic anhydride also forms benign acetic acid as a waste when mixed with water. The choice of ferrocene as the reagent enables the use of phosphoric acid instead of AlCl3 as it is highly reactive. One of the disadvantages of this reaction is that ferrocene is listed as harmful and highly flammable.
Phosphoric acid is listed as corrosive. Acetic anhydride is listed as causing respiratory tract irritation and severe eye irritation, is flammable, corrosive and can have and very reactive with water.
The purification involves a recrystallization with hexane, nullifying its claim that no organic solvents were used. Let us write you a custom essay sample on The Friedel-Crafts Reaction: A more green reaction involves the use of Nafion strips to act as the acid catalyst and microwave heating.
The acidic hydrogen ion form and derivatives are solid, superacid catalysts useful in a wide variety of synthetic applications. Microwave heating reduces energy requirements and appeared to reduce the amount of side-products formed.
A Greener Approach by Kurt R.Ferrocene does not undergo addition reactions typical of cyclopentadiene, but undergoes electrophilic aromatic substitution. The Friedel-Crafts acylation reaction of ferrocene involves the addition of the acylium cation to one of the carbon atoms on the ring, followed by loss of a proton (to solvent).
Mar 28, · What is the mechanism for the Friedel-Crafts acylation of ferrocene to produce acetylferrocene? Explanation or website would be appreciated. Looking for the full mechanism (with curved arrows), not just the equationStatus: Resolved.
8. Weigh out mg of ferrocene and put into a clean vial 3 mL vial.
Add mL of CH2Cl2, cap tightly and shake to dissolve. 9. Add the ferrocene solution (using your syringe) through the septum of the 3 mL vial and the septum of the Claisen head.
The solution in the vial should immediately turn dark purple. The Friedel-Crafts acylation reaction created acetylferrocene and diacetylferrocene, using phosphoric acid as a catalyst for the reaction between acetic anhydride and ferrocene (once applying heat).
During column chromatography, a solution is passed through a filtration system of silica, sand, and cotton. Acylation of ferrocene: a new approach Mirjana D.
Vukic´evic´,a Zoran R. Ratkovic´,a Aleksandar V. Teodorovic´,a Gordana S. Stojanovic´b and Rastko D. Vukic´evic´a,*. With the Friedel-Crafts acylation reaction, this mechanism is used to add acyl groups to aromatic compounds.
For a Friedel-Crafts acylation, the acylating agent commonly used is ethanol chloride.