lab report

1. Name
6/07/2021
Experiment: Preparation of Acetylferrocene
Purpose: To synthesize acetylferrocene from Ferrocene and calculation of percentage yield.
Friedel craft’s acylation of benzene is done in the presence of catalyst whereas ferrocene with very
high pi electron density, referred to as super aromatic compound, can undergo acylation in mild
conditions. Acetylferrocene is formed by Friedel craft’s acylation reaction. But diacetyl ferrocene
will be formed under vigorous conditions as acetyl group is deactivating. Second acetyl group will
add on non acylated ring.
Procedure: add 3 g Ferrocene, 10ml acetic anhydride, 2 ml phosphoric acid (85%) in round
bottom flask. Attach reflux condenser with drying tube and reflux it for 10 min after dissolution.
Pour the reaction mixture onto 50g crushed ice. Add 75ml sodium hydroxide (10%) then sodium
bicarbonate and allow it to stand for 20 min. collect the product by suction filtration. Dissolve the
crystals in hexane or ligroin by boiling on steam bath and separate gummy residue. Reduced the
solvent using steam bath, cool it at room temperature and collect dark orange crystals.
Purification of acetylferrocene
Acetylferrocene formed in the reaction mixture can be purified by column chromatography.
Reaction mixture is checked by thin layer chromatography using toluene and ethanol in 3:1 which
shows mixture contain ferrocene, acetylferrocene and diacetyl ferrocene. So reaction mixture is
passed through column chromatography to obtain pure acetyl ferrocene.
Fig.1. Chromatogram showing components in reaction mixture

2. Calculations
Reaction
Ferrocene react with acetic anhydride which is acylated reagent in the presence of phosphoric acid
to form acetylferrocene. Acetylferrocene can be separated from ferrocene by column
chromatography.
Mechanism

3. Physical and chemical properties
 Melting Point, 81-83o
C
 Boiling point, 160-163o
C
 Density, 1.014 g/cm3
 Solubility, Insoluble in water but soluble in most organic solvents
Percentage yield calculation
Actual yield= 1.3g
Theoretical yield
Mass of ferrocene=3g
Molar mass of ferrocene=186.04g
No of moles of ferrocene=3/186.04
=0.016moles
Mass of acetic anhydride= density*volume = 1.08*10= 10.08g
No of moles of acetic anhydride= 10.08/102.09
=0.1moles
As no of moles of ferrocene is less than acetic anhydride, so ferrocene will be limiting reagent.
1 mole of ferrocene produced acetylferrocene= 1 moles
0.016 mole ferrocene produced acetylferrocene= 0.016moles
Molar mass of acetylferrocene= 228.08g
Mass of acetylferrocene = 0.016*228.08
=3.65g
Theoretical yield = 3.65g
Percentage yield= Actual yield/Theoretical yield*100
= 1.3/3.65*100
=36%
Percentage yield is 36%.

4. Discussion
Acetylferrocene was synthesized from ferrocene and acetic anhydride in the presence of
phosphoric acid through Friedel craft’s acylation reaction. Crystals of acetylferrocene was
obtained by pouring onto crushed ice and neutralizing the mixture with sodium hydroxide/ sodium
bicarbonate solution. The crude crystals obtained was purified through column chromatography
by using hexane solvent which can separate ferrocene, acetylferrocene and diacetyl ferrioocene.
Then percentage yield of acetylferrocene is calculated.
Conclusion
Acetylferrocene was synthesized and then purified in different steps to obtain pure orange crystals.
Percent yield obtained for acetylferrocene is 36%.
Post lab questions
Why does the second acetyl group enter the unoccupied ring to form diacetyl ferrocene?
Acetyl group is deactivating group so acylation of ferrocene results decrease in electron density
on ring that’s why ring containing acetyl group cannot add second acetyl group on same ring.
Why sodium hydroxide and sodium bicarbonate is used?
Sodium hydroxide and sodium bicarbonate is used to neutralize the reaction mixture as reaction is
carried out in the presence of acid.