Lab 5 Separating Ferrocene and Acetylferrocene by Adsorption Column Chromatography

Lab 5 Separating Ferrocene and Acetylferrocene by Adsorption Column Chromatography

Background

Chromatography is just one technique of analyzing and separating compounds (14). Although there are several types of chromatography, the basic fundamental of this process is the distribution of components of a mixture between two phases (14). These phases are known as the stationary phase and the mobile phase. The stationary phase is the substance that does not move and contains the adsorbent, and the mobile phase is the liquid or gas that carries the sample (14). The individual components of a mixture exist in equilibrium between the stationary and mobile phases (14). In many cases, the mobile phase is added after the stationary phase, and as it moves down the column it carries with it all the components of the mixture (14). Depending on the compounds, each compound is adsorbed differently (14). For example, compounds that favor the stationary phase are held longer, which results in slower movement (14). Whereas, compounds that favor the mobile phase are pushed out quicker (14).

The effectiveness of the mobile phase is dependent on the stationary phases adsorbent and the sample of the solvent in the mobile phase (14). The more polar the compound, the more tightly it will hold on to the stationary phase (14). On the other hand, the more polar the solid phase, the tighter it will hold on to the mobile phase (14). Therefore, the greater the polarity of a solvent correlates to a greater ability for the compound to move quickly (14).

Aim

The purpose of this lab was to separate a two-compound mixture using column chromatography and to calculate the percent recovery for each compound. Specifically, we separated ferrocene from acetylferrocene using the dry pack method.

Table of Physical Properties

Name of Chemical	Chemical Formula	Melting Point	Boiling Point	Solubility in water	Density
Ferrocene (1)	C10H10Fe	172.5°C (or 342.5°F)	249°C (or 480.2°F)	Insoluble	1.11g/cm³
Acetylferrocene (2)	[Fe(C5H4 COCH3) (C5H50)]	81°C - 83°C (or 178°F181°F)	161°C (or 321.8°F)	Insoluble	1.014g/mL
Hexane (3)	C6H14	-96°C – -94°C (or 141°F – -137°F)	68°C (or 154.4°F)	9.5mgL^-1	655kg/m³
Acetone (4)	C₃H₆O	-95°C (or -139°F)	56°C (or 132.8°F)	Miscible	791kg/m³
Ethyl Acetate (5)	C4H8O2	-83.6°C (or - 118.5°F)	77.1°C (or 170.8°F)	8.3g/100mL (at 20°C)	897kg/m³
Silica Gel (6)	SiO₂·xH₂O	1,625°C (or 3,115°F)	2,230°C (or 5,430°F)	1.648 (αquartz) 2.196 (amorphous) g/cm-3	2.21g/cm³

Hazards

Name of Chemical	Chemical Formula	Hazards
Ferrocene	C10H10Fe	-combustible (7). -inhalation can cause sore throat (7). -exposure to skin can cause redness (7). -exposure to eyes can cause redness and pain (7).
Acetylferrocene	[Fe(C5H4 COCH3) (C5H50)]	-may be fatal is swallowed; poison by ingestion (8). -toxic is absorbed through the skin (8). -may cause eye, skin, and respiratory tract irritation (8). -may cause digestive tract irritation (8).
Hexane	C6H14	-highly flammable (9). -vapor/air mixtures are explosive (9). -inhalation may cause dizziness, drowsiness, dullness, headache, nausea, weakness, unconsciousness (9). -contact with eyes can cause redness and pain (9). -ingestion can cause abdominal pain (9).
Acetone	C₃H₆O	-highly flammable (10). -vapor/air mixtures are explosive (10). -inhalation can cause sore throat, cough, confusion, headache, dizziness, drowsiness, and unconsciousness (10). -contact with skin causes dry skin (10). -exposure to eyes can cause redness, pain, blurred vision; possible corneal damage (10). -ingestion can cause nausea and vomiting (10).
Ethyl Acetate	C4H8O2	-highly flammable (11). -vapor/air mixtures are explosive (11). -inhalation can cause cough, dizziness, drowsiness, headache, nausea, sore throat, unconsciousness, and weakness (11). -can cause dry skin (11). -contact with eyes can cause redness and pain (11).
Silica Gel	SiO₂·xH₂O	-can cause respiratory tract irritation (12). -can cause eye and skin irritation (12). -target organs: lungs (12). -can cause irritation of digestive tract (12).

Introduction

The basic principles of column chromatography are as followed: input, sample, column, stationary phase, mobile phase, cotton plug, and output (Figure 1) (15). The main purpose of column chromatography is to separate components of a mixture. Those with a lower attraction and adsorption to the stationary phase move quicker and are eluted out first (15). Whereas, those with a greater attraction move out slower and get eluted out last (15). For column chromatography, sand is usually recommended to be the stationary phase or the adsorbent (15). The mobile phase use either a single solvent or a mixture of solvent, depending on the separation you are doing (15). Lastly, cotton is used to plug the exit of the column to hold the stationary phase and to make sure only what is supposed to exit is allowed to exit (15).

Procedure and Observations

First, we took a microscale pipette and placed a small piece of a ball of cotton and set it on a stand.
Next, we measured out sand and funneled it into the pipette. To make sure the sand was evenly distributed and flat, we tapped the sides of the pipette.
Silica gel was then funneled next into the pipette. We measured out approximately 3.0g of silica gel (exact: 3.03g) and filled the silica gel until it was almost to the top of the pipette. We made sure to once again tap the sides of the pipette to make sure the silica gel was evenly distributed and flat.
Next, we measured out more sand and filled the pipette. We measured out enough sand to just cover the silica gel. We tapped the pipette to make sure the sand was evenly distributed and flat.
We placed a disposal beaker beneath the pipette.
We then slowly added hexane 1mL at a time. By doing this, the less polar compound, ferrocene, was removed from the column.
Once we saw that the yellow band was no longer in our column and was completely extracted, we poured our ferrocene into an Erlenmeyer flask and labeled it.
We placed a disposal beaker once again beneath the pipette and began to slowly add 1mL of ethyl acetate. When ethyl acetate was added, it extracted the more polar compound, which was acetylferrocene.
Once the orange band was completely extracted from the pipette, the disposal beaker was switched from an Erlenmeyer flask and was labeled.
We then placed both our ferrocene and acetylferrocene compound into small vials.
We took these vials and placed them in the rotameter to yield crystals.
Finally, the crystals were weighed, and results were recorded.

Results

Ferrocene- yellow band
Acetylferrocene- orange band
We weighed exactly 0.7g of the 50/50 mixture (ferrocene (0.35g) and acetylferrocene (0.35g)).

Yields:

Ferrocene:

Weight of vial (without cap) = 12.85g
Weight of ferrocene + vial (without cap) = 12.94g

12.94g − 12.85g = 0.09g

= 0.257 x 100% = 25.7%

Acetylferrocene:

Weight of vial (without cap) = 12.88g
Weight of acetylferrocene + vial (without cap) = 12.92g

12.92g − 12.88g = 0.04g

= 0.114 x 100% = 11.4%

Total Yield

0.09g + 0.04g = 0.13g

0.13g

= 0.186 x 100% = 18.6%

0.7g

Conclusion

The purpose of this experiment was to separate ferrocene and acetylferrocene using column chromatography. Sand in this experiment was used to protect the silica stationary phase so when additional solvent was added, the column would not be disrupted. Column chromatography separates compounds based on polarity. Since hexane is nonpolar, the more nonpolar solvent, ferrocene, eluted from the column first. Then, ethyl acetate eluted the more polar solvent, acetylferrocene. Different compounds travel at different rates due to their attraction in the stationary phase, and also because of differences in solubility.

There are several real-life applications of column chromatography, such as forensic testing and performance enhancing drug testing (13). In forensic testing, gas chromatography is often used for crime scene testing, arson verification, or blood testing after death to determine levels of intoxicants in the body (13). For performance enhancing drug testing, using chromatography can identify substances in the bloodstream, which can indicate whether or not athletes have been taking performance enhancing drugs.

Unfortunately, in this experiment, we did not obtain very high yields for either ferrocene or acetylferrocene. Both yields were very low and there could have been several errors that occurred to cause these low yields. One error could be that when the sample was being funneled into the pipette, the samples could have stuck to the walls in the pipette, causing this lower yield. Another error that could have occurred is just by simple experimentation. It is expected in this experiment for some of the original sample to be lost in the adsorbent. Another possible error could have been that our sand and silica gel was not evenly distributed, making the bands elute unevenly. This could have caused an ineffective separation, and caused our yields to be low. Seeing these results, we could have benefitted re-doing the experiment to get more accurate data and to try and prevent some of these errors from occurring.

References

Wikipedia. (2017, June 20). Ferrocene. Retrieved from:

https://en.wikipedia.org/wiki/Ferrocene (1)

Wikipedia. (2017, June 2). Acetylferrocene. Retrieved from:

https://en.wikipedia.org/wiki/Acetylferrocene (2)

Wikipedia. (2017, June 22). Retrieved from:

https://en.wikipedia.org/wiki/Hexane (3)

Wikipedia. (2017, June 25). Retrieved from:

https://en.wikipedia.org/wiki/Acetone (4)

Wikipedia. (2017, June 7). Retrieved from:

https://en.wikipedia.org/wiki/Ethyl_acetate (5)

Book, Chemical. Silica Gel. Retrieved from:

http://www.chemicalbook.com/ProductMSDSDetailCB1199389_EN.htm (6)

Centers for Disease Control and Prevention. (2014, July 1). Ferrocene. Retrieved from:

Sheet, Material Safety Data. (2008, January 24). Acetylferrocene. Retrieved from:

https://fscimage.fishersci.com/msds/69220.htm (8)

Centers for Disease Control and Prevention. (2014, July 1). Hexane. Retrieved from:

Centers for Disease and Control Prevention. (2014 July 1). Acetone. Retrieved from:

Centers for Disease and Control Prevention. (2014 July 1). Ethyl Acetate. Retrieved from:

Sheet, Material Safety Data. (2009, July 20). Silica Gel. Retrieved from:

https://www.nwmissouri.edu/naturalsciences/sds/s/Silica%20Gel%20mesh.pdf (12)

Online, Labmate. (2014, December 4). 5 Uses of Chromatography in Everyday Life. Retrieved from:

https://www.chromatographytoday.com/news/industrial -news/39/breaking -news/5 -uses -

of -chromatography -in -everyday -life/32639 (13)

Column Chromatography and Thin Layer Chromatography (TLC). Retrieved from:

https://atc.io/files/OL/Experiment2b.pdf (14)

Read, Study. Column Chromatography Principle, Procedure, and Applications, Retrieved from:

https://www.studyread.com/column -chromatography (15)

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