Chem 3106-313 Exp 6 - lab report PDF

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Isabelle Smola Lab Partner – Sarah West 3.10.2021, CHEM 3106-313 TA – Aneelman Brar Column Chromatography Purpose: To be able to separate and purify solids and liquids. To be able to perform and analyze and IR spectrum and column chromatography. Reactions and Physical Properties Table: Physical Properties of Chemicals Reagents and Solvents

Ferrocene Acetylferrocene Diacetylferrocene Dichloromethane Hexane Methanol Alumina

MW (g/mol)

Density (g/mL)

Bp (°C)

186.04 228.07 262.05 84.93 86.18 32.04 101.96

1.11 1.01 1.33 0.66 0.79 3.95

249 161 166.6 39.6 69 64.7 2977

Melting point (°C) 172.5 81 122 -96.7 -95 -98 2072

Table 1.

Figure 1: Treatment of ferrocene with acetyl chloride and trichloro aluminum produces a mixture of acetylferrocene and dicetylferrocene

Safety: The following is data obtained from the safety and documentation information made available at fishersci.com and kovaintl.com. Ferrocene Risk Statements: Flammable Acute Oral Toxicity Safety Statement: If inhaled remove victim to fresh air. If on skin immediately take off all contaminated clothing and wash skin thoroughly. If in eyes rinse cautiously with water for several minutes. Keep away from heat, sparks, open flame, and hot surfaces. Wear protective gloves, clothing, eye protection, and face protection.

Acetylferrocene

Risk Statements: Skin Corrosion/Irritation Serious Eye Damage/Irritation Specific Target Organ Toxicity Safety Statement: If inhaled remove victim to fresh air. If on skin immediately take off all contaminated clothing and wash skin thoroughly. If in eyes rinse cautiously with water for several minutes. Wear protective gloves, clothing, eye protection, and face protection. Diacetylferrocene Risk Statements: Serious Eye Damage/Irritation Skin Corrosion/Irritation Specific Target Organ Toxicity Safety Statement: If on skin immediately take off all contaminated clothing and wash skin thoroughly. If in eyes rinse cautiously with water for several minutes. Wear protective gloves, clothing, eye protection, and face protection. Do not breathe in dust, fumes, gas, vapor, mist, or spray. Dichloromethane Risk Statements: Serious Eye Damage/Irritation Flammable Skin Corrosion/Irritation Specific Target Organ Toxicity Carcinogen Safety Statement: If inhaled remove victim to fresh air. If on skin immediately take off all contaminated clothing and wash skin thoroughly. If in eyes rinse cautiously with water for several minutes. Wear protective gloves, clothing, eye protection, and face protection. Do not breathe dust, fume, gas, mist, vapor, or spray. Hexane Risk Statements: Serious Eye Damage/Irritation Flammable Skin Irritant Reproductive Toxicity Aspiration Hazard Specific Target Organ Toxicity Hazard to aquatic environment

Safety Statement: If inhaled remove victim to fresh air. If on skin immediately take off all contaminated clothing and wash skin thoroughly. If in eyes rinse cautiously with water for several minutes. Wear protective gloves, clothing, eye protection, and face protection. Do not breathe dust, fume, gas, mist, vapor, or spray. Methanol Risk Statements: Serious Eye Damage/Irritation Flammable Acute Oral/dermal/inhalation toxicity Specific Target Organ Toxicity Safety Statement: If inhaled remove victim to fresh air. If on skin immediately take off all contaminated clothing and wash skin thoroughly. If in eyes rinse cautiously with water for several minutes. Wear protective gloves, clothing, eye protection, and face protection. Do not breathe dust, fume, gas, mist, vapor, or spray. Alumina Risk Statements: Serious Eye Damage/Irritation Specific Target Organ Toxicity Respiratory Tract Irritation Lung Damage Safety Statement: If inhaled remove victim to fresh air. If on skin immediately take off all contaminated clothing and wash skin thoroughly. If in eyes rinse cautiously with water for several minutes. Wear protective gloves, clothing, eye protection, and face protection. Do not breathe dust, fume, gas, mist, vapor, or spray.

Physical safety: Dispose of all chemicals to the proper waste container. Procedure: 1. Add ~1 mL of CH2Cl2 to the vial containing the crude product from Experiment 5. Use this solution to spot a TLC plate using a spotting capillary. Ferrocene will be provided for making a spotting solution for comparison. If there is a community solution spot this solution next to your crude product mixture spot on the TLC plate. Otherwise prepare a solution by dissolve a tiny bit (a little solid on the tip of a spatula) in ~1 mL of CH2Cl2 and spot the solution on your TLC plate.

2. Develop the spotted TLC plate with CH2Cl2. Using the ferrocene reference spot, determine if there is any remaining ferrocene in the crude product mixture. Dry pack the column used in this experiment. 3. Push a piece of cotton to the bottom of the column. It needs to hold the sand and alumina in place. Do not pack it very tightly. Tightly packed cotton will slow the flow of solution through it and it will take much longer to run solvents through the column to separate the mixture. 4. Add a small amount of sand to the column. Add alumina to the column. A powder funnel makes this easy. Only ~2-3 inches of alumina is needed for this experiment. Unless there is a lot of solid to chromatograph, a shorter column of 2 inches should be sufficient to separate the mixture and will take less time for the solvent to elute through the column.

5. Add the solution of the crude product mixture to ~0.3 g of alumina in a small beaker and evaporate the solvent by gently blowing compressed air over it in the hood. Scrape the product/alumina mixture from the beaker and add it to the top of the column. This is dry loading the mixture onto the column so that the elution should give nice level bands as it preforms the chromatography experiment. The column should ultimately look something like the following:

6. Once the alumina with the mixture has been added to the column, sand should be added to the top of the column. This helps minimize the disruption of the material being chromatograph when solvent is added to the top of the column. Once you add solvent to the column do not let the column go dry. This means do not allow the liquid level to drop below the top of the alumina in the column. This allows air into the column and can cause the bands to elute unevenly. If the solvent level is getting low, turn the stop cock to stop the flow while more of the solvent/solvent mixture is obtained.

7. Add the solvent down the sides of the column. Try to avoid disturbing the solid in the column. A pipet can be used to add a solvent mixture by putting the tip to the side and slowly adding the liquid. Once there is a layer (3 or more inches) of liquid on top of the column that can cushion the addition of more liquid, the solvent mixture can be poured into the column slowly. In this experiment, the compounds that are separating are all colored so it is easy to see when they are coming off the column. Each band will be collected separately and the solvent will be evaporated in the hood to isolate the compound present in the fraction. Collect the colored solutions separately from the colorless solvent that elutes from the column before and after each band as it moves down the column to avoid needless evaporation of solvent that does not contain important compound. 8. It is easy to see each band move down the column as it elutes. As it gets near the bottom and are trying to determine if it is coming off the column you can hold a white piece of paper behind the bottom part of the column to better visualize if the solution is colored. Additionally, collecting a small amount in an empty container and hold it against a white background and help determine if a colored solution is being collected. The amount of solvent needed to elute each fraction will depend on how long the column is and how much of each compound is present in the mixture. 9. When preparing solvent mixtures for eluting more polar compounds from the column, the solvents must be mixed to get a homogenous solution. At this point you are ready to start adding solvent. What solvent used will depend on what is wanted to elute from the column. 10. If the TLC of the product mixture shows the presence of ferrocene it will need to elute this from the mixture first. If not proceed to the next solvent mixture to elute the acetylferrocene in your mixture. 11. Use hexane to elute the ferrocene from the column. Keep the stop cock open initially as enough hexane is added to fill the column. This will displace air that is in the column. Once the liquid level reaches above the alumina, do not want to let the solvent level to ever be lower than the alumina while running the column. As the hexane is added there should be a colored band move down the column. Try to collect only the colored solution in a beaker or flask separately from the colorless hexane that will come through the column ahead of the band. 12. Once the solution coming from the column is no longer colored the ferrocene has eluted from the column. The colorless hexane used to initially move the ferrocene down the column can be recycled to make the 1:1 hexane:CH2Cl2 solvent mixture used in the next step. 13. Use a 1:1 mixture of hexane:CH2Cl2 to elute the acetylferrocene from the column. If this doesn't seem to be move the band efficiently enough use straight CH2Cl2 to elute the column. If there is not any ferrocene in your mixture and this is the first solvent mixture to initially be added to the column, keep the stop cock open initially as enough

hexane/dichloromethane is added mixture to fill the column. This will displace air that is in the column. Once the liquid level reaches above the alumina, do not want to let the solvent level to ever be lower than the alumina while running the column. If it is already eluted ferrocene from the column, start using the 1:1 mixture of hexane:CH2Cl2 to elute the column. Try to collect only the colored solution in a beaker or flask separately from the colorless solvent that will come through the column ahead of the band. 14. Once the solution coming from the column is no longer colored the acetylferrocene has eluted from the column. Elution of diacetylferrocene: Most people should have some diacethylferrocene in the crude product mixture. There should still be a colored material on the column at this point if the mixture contained this. A 9:1 mixture of CH2Cl2:CH3OH is used to elute the diacetylferrocene band from the column. Try to collect only the colored solution in a beaker or flask separately from the colorless solvent that will come through the column ahead of the band. 15. The solvent from each colored fraction is evaporated in the hood using compressed air and gentle heating. The mass of each isolated solid part of the initial mixture needs to be determined to determine the actual yields of each product. 16. Once all of the compounds have eluted from the column allow all of the solvent to drain from the column. The alumina can be gently blown into the solid chemical waste container by inverting the column over the waste container and gently blowing compressed air through the column from the tip with the stopcock open. Initially the air will evaporate solvent from the column and it will become cold. As the alumina dries it will begin to flow into the waste container. After cleaning the column, place it back in the hood for the next class. If a column is broken during class, let the TA know so the pieces can be saved for repair. 17. For time reasons, an IR spectrum will be obtained for ferrocene, acetylferrocene, and diacetylferrocene each using student isolated samples and distributed to the class. There are spectra in the Experiment 6 folder on Blackboard for each compound to compare experimental results with. Check each fraction by TLC to confirm its purity. A stock solution of acetylferrocene and diacetylferrocene will be provided to spot next to your spots for each fraction for identification purposes. If the product isolated was ferrocene from the product mixture, this is starting material that did not react. Take this into account when determining the amount of starting material that reacted to give product. It is easier to determine the percent yield for acetylferrocene and diacetylferrocene using a mole ratio of isolated product: ferrocene consumed in the reaction. For example if 0.13 mmol of acetylferrocene is isolated in the column chromatography experiment and after taking into account isolated ferrocene from the column it was determined that 0.60 mmol of starting ferrocene was consumed in the reaction, the percent yield of acetylferrocene would be (0.13/0.60)x100 = 22%. Data and Observations: At the start of the experiment all the layers were separated and distinct in color from tan to orange to white. Once hexane was used to elute the layers began to blend and bleed as the orange

color dripped down and a yellow solution was at the bottom and began to rise up. Once the CH2CL2 was added the layers became more blended and almost all of the solution was either orange or tan in color. Once the CH3OH was added the layers separated more and a thin layer of orange was left while white and tan consumed most of the vessel. When the reaction was complete the orange was gone. When each solution was separated the first one appeared a light yellow in color. The second one appeared orange in color and the third one appeared a light orange in color. Once the products were evaporated and solid product remained the first one had long streaks like crystallization had occurred, the second one was a bright powdery orange, and the third one was orange, brown in color. Calculations and Results: Mass of Starting Mixture: 0.1022 g Mass of empty beaker 1: 25.5816 g Mass of beaker with solid from fraction 1: 25.6016 g Mass of product 1: 0.02 g !"#$% !)))--./ Actual yield of Ferrocene: 0.002$g$$x$ 𝑥 = 0.01075𝑔 !&'.)*"+/#

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Percent Yield:$$ 𝑥$100% = 1.792% ).') Mass of empty beaker 2: 28.9357g Mass of beaker with solid from fraction 2: 29.0037 g Mass of product 2: 0.068 g Actual Yield of mono-acetylferrocene: 0.068$g$$x$

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%$22&.)0"+/#

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%$= 0.29815𝑔

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Percent Yield: $ $𝑥$100% = 49.69% ).') Mass of empty beaker 3: 31.6434 g Mass of beaker with solid from fraction 3: 31.6493 g Mass of product 3: 0.0059 g !"#$% Actual yield of diacetylferrocene: $0.0059g$$x$

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Percent Yield:$ 𝑥$100% = 5.285% ).') Rf Values: Ferrocene: 3.5 cm / 3.7 cm = 0.9459 Mono-substituted: 0.9 cm / 4 cm = 0.225 Di-substituted: 0.2 cm / 3.6 cm = 0.0556

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%$= 0.03171𝑔

Figure 2: TLC of Starting Material Figure 3: TLC of 1st fraction

Figure 4: TLC of 2nd fraction

Figure 5: TLC of 3rd fraction

Figure 8: IR of 3rd Fraction

Figure 6: IR of 1st Fraction

Figure 7: IR of 2nd Fraction

Conclusion/Discussion:

This experiment carried out the Friedel-Crafts Reaction and isolated the products relatively successfully. The TLC plates show that the products were collected in the right order and the most contaminated was ferrocene. Hexane, CH2Cl2, and CH3OH were successful in carrying only a single product through the other products down the collection vessel. Each of the solvents were specific to each of the three products so they could all be isolated correctly. The IR spectrum of the 3rd fraction which is also diacetlyferrocene has a major peak at 1653 which is the carbonyl bond. Acetylferrocene has a major peak at 1659 which is also a carbonyl group. Ferrocene was the IR spectrum with the least number of peaks. Ferrocene had the highest RF value of 0.9459 and this is because it is the least polar. Diacetylferrocene had the lowest RF value of 0.0556 because it is the most polar product. Polar products barely travel while non-polar products travel the farthest. Post lab Questions: 1. Rank ferrocene, acetylferrocene, and diacetylferrocene in order of increasing polarity. Do the TLC results from your fractions support this ranking? Explain. Ferrocene >Acetylferrocene > Diacetylferrocene The TLC plates do not support this order of increasing polarity because the places where the spots were are different. 2. Rank the solvents used in the experiment in order of increasing polarity. Since, hexane is a completely non-polar solvent because it contains a hydrocarbon chain with molecular formula C6H14 the polarity of hexane is increased by adding some polar solvents such as ethyl acetate or methylene chloride so, the increasing order of polarity of solvents is Hexane < 1:1 mixture of hexane: methylene chloride < 9:1 mixture of methylene chloride: hexane 3. Why do you start with the least polar solvent/solvent mixture and progress to increasing polar solvent/solvent mixtures when eluting the ferrocene compounds from the column rather than starting with more polar solvent system and progressing to less polar solvents? All chromatographic techniques have a stationary phase as well as a mobile phase. In column chromatography, the silica gel which is used in packing of column is the stationary phase and the solvent that we pour is the mobile phase. Silica gel is highly polar in nature and so when we begin with a non-polar solvent, the polar components of the mixture will bind strongly to the silica gel but, the non-polar component flows out with the solvent. With a particular polarity of solvent, a compound with polarity more than that will never be eluted. If we would have started with a more polar solvent, the entire mixture would have eluted at once so, to ensure a better separation we begin with the least polar solvent and progressively increase the polarity as the desired component is eluted. 4. How do the thin layer and column chromatography for this experiment compare in regard to stationary and mobile phases? Both the TLC and column chromatography have the same stationary phase which is the silica gel. Also, the same solvent mixture in both the techniques is used so, the result of the two are almost the same. The only difference observed is that TLC works against the gravity and column chromatography works in the direction of the gravity. The component

which travels the least distance on TLC plate will be eluted the last from the column and vice versa.

5. What key feature in the IR spectrum of acetylferrocene distinguishes it from the spectrum of ferrocene? The key feature in the IR spectra of the acetylferrocene that will be absent in the spectrum of ferrocene is the presence of carbonyl stretching frequency at around 1600 cm-1. This peak can distinguish between acetyl ferrocene and ferrocene....