The purpose of the lab is to prepare ferrocene from ferrous chloride and cyclopentadiene. Ferrocene, an organometallic, is a combination of two cyclopentadienide ions with a ferrous cation, such that the six pi electrons binds every carbon equally to the metal forming a sandwich type structure. Ferrocene has the properties of both an activated benzene (undergoes electrophilic substitution reactions) and a ferrous ion (oxidation reaction). Glyme and DMSO are used as solvents as they have moderate polarity so they would break up KOH into K+ and OH-, without breaking the hydrogen bonding in the hydroxide ion. Cyclopentadiene is relatively acidic so a strong base would be needed to abstract a proton to form the cyclopentadienide anion (OH- from KOH).
8 g of potassium hydroxide, 20 mL of 1,2-dimethoxyethane, and 2 ml of cyclopentadiene were added to a 100 ml round bottom flask. The mixture was swirled for 10 minutes. 2.4 g of ferrous chloride hydrate and 12 ml of dimethyl sulfoxide were added to a 125 ml Erlenmeyer flask. The FeCl2 was warmed in a warm water bath for five minutes, and then cooled in an ice bath until 10°C was reached. The solution was then transferred into a separatory funnel, and was added to the round bottom flask solution dropwise over ten minutes while agitating.
The contents of the round bottom flask were poured into a beaker with 40 g of ice and 35 ml of 6M HCl. The flask was then rinsed with three 20 mL portions of water, and poured into the beaker. The solution was filtered through a Buchner funnel, and washed with 20 ml of cold water.
FLOWCHART IS SHITTY
Table of chemicals:
Chemical| Quantity| MW or % Comp|
KOH| 8.071 g| 56.12 g/mol|
C4H10O2| 20.7 mL| 90.12 g/mol|
C5H6| 2 mL| 66.1 g/mol|
FeCl2| 2.413 g| 126.75 g/mol|
DMSO| 12 mL| 78.13 g/mol|
HCl| 35 mL| 6M|
H2O| (3x) 20 mL; 20 mL wash| 18.01 g/mol|
The KOH resembled pellets of wax. The 1,2-dimethoxyethane was a clear and colorless solution with a terrible smell. The cyclopentadiene was also a clear and colorless solution with an even worse smell. Once all were added, the solution in the round bottom flask was brown and mucky. After swirling, the solution became darker with black visible clumps/grains.
FeCl2 was a green, pebbly powder. The DMSO was clear and colorless. When combined in the Erlenmeyer flask, the solution was clear and yellow. After heating and cooling in the ice bath, the solution resembled tea; it was dark brown and clear. After adding the solution dropwise into the round bottom flask, the solution turned a dark black color. Once the flask was washed with water and the contents poured into a beaker, the solution had two layers; the top thin layer was orange and oil-like, and the bottom was a dark green-black solution. After Buchner filtration, the filtrate was an aquamarine clear solution, while the residue was an orange-brown mat with a distinct smell.