By Joseph and Bam

Manganese Oxide for Catalytic Oxidation of Benzyl Alcohol

The Lab Team

Tests

X-Ray Diffraction Gas Chromatography

The Oxidation of Benzyl AlcoholForm

BenzaldehydeBenzyl Alcohol + Toluene +

MnO2

Formation of the Manganese Oxide

Catalyst KMnO4 + H2SO4

KMnO4 +H2SO4 MnO2

MnO2+ Toluene+ Benzyl Alcohol

Part 1

Part 2

Outline of the Experiment

Benzaldehyde!!!

Purpose

Hypothesis

The purpose of this experiment is to perform catalytic oxidation reaction in order to get a product of Benzaldehyde with high selectivity. The oxidation of alcohols to the corresponding carbonyl compounds is a key reaction in organic synthesis.

We hypothesized that the Benzaldehyde can be synthesize through a series of oxidation reaction. The reason for making such Hypothesis is based on my Chemistry class understanding on chemical reactions and filtration.

Materials

•A Balance•KMnO4 (0.1 M)•Fe(C5H5)2 (20 mg)•H2SO4 (0.5 ml)•Water•Round Bottom Flask•Pipette•Filter paper•Funnel•Benzyl alcohol (0.1034 l)•Toluene (10 ml)•Condenser•Tissue Paper

1. First obtain the materials: KMnO4 (0.1 M), ferrocene (20 mg), and H2SO4 (0.5 ml) by their correct masses.

2. Add 25 ml of water into the KMnO4.

3. Add the H2SO4 to the ferrocene using a pipette. The color will gradually change from orange to dark green. This produces the solution called ferricinium.

4. Using a dropper, carefully drop all the ferricinium into the KMnO4 solution under the hood.

5. After a while, the water evaporates and the solution changes from purple to brown. 6. Filter the solution with a filter paper and a funnel. 7. Place the filter solution (manganese (IV) oxide) in an iso-temperature oven at 110 degrees Celsius for 24

hours. 8. Measure the mass of the manganese (IV) oxide.9. Take the manganese (IV) oxide for x-ray defraction to determine its phase. 10. After determining its phase, perform to oxidation of benzyl alcohol.11. Pour benzyl alcohol (0.1034 l), toluene (10 ml), and manganese (IV) oxide (100 mg) into a round-bottom flask. 12. Connect the flask to a condenser which is also connected to a cooling aid. Heat the solution for 3 hours.13. Filter the solution through filter paper and a funnel.14. Add sodium sulphate to absorb the water out.15. The filtration process continues as the solution is being filtered with a micro-optic filter paper.16. Perform the gas chromatography test on the solution.

Procedures

Results and Analysis

Formation of the Manganese (IV) Oxide

KMnO4 + H2SO4 MnO2

Solution Mass

KMnO4 0.3973 g

Ferrocene

0.021 g

Solution Volume

Sulfuric Acid 0.5 ml

Water 25 ml

The manganese oxide was synthesized by the oxidation of manganese sulfate with potassium permanganate in an acidic medium at room temperature. This was formed by 0.3951 grams of potassium permanganate, 20 mg of ferrocene, and 0.5 ml of sulfuric acid, and 25 ml of water.First, we added the sulfuric acid to the ferrocene. The solution turned from orange to green color. After adding water to it, the color becomes purple. Then, we carefully added potassium permanganate into the solution. We waited for the KMnO4 solution to evaporate as it stirred constantly and placed under a hot plate. The color eventually changed from purple to brown. After that, we filtered the solution with the filtering apparatus.

Oxidizing Benzyl Alcohol

Benzyl Alcohol + Toluene + MnO2

Solution Amount

Benzyl Alcohol 0.1034 g

Toluene 10 g

MnO2 100mg

The catalytic oxidation of benzyl alcohol was carried out in a round-bottom flask with a condenser and magnetic stirrer. In the round-bottom flask are benzyl alcohol (0.1034 g), toluene (10 g), and the manganese oxide we previously filtered (100mg). As seen in the pictures, the condenser is connected to a cooling aid to prevent the solution from evaporating. Also, tissues are used to cover around the tube to prevent water from going in. After waiting for approximately 3 hours, we took the flask for a cool down under ice water and filtered the solution. During the filtration, we added sodium sulfate to absorb the water. The filtration process continues as the solution is being filtered with a micro-optic filter paper.

X-ray diffraction (XRD) is a versatile, non-destructive technique that reveals detailed information about the chemical composition and crystallographic structure of the solution. It is widely used in chemistry and biochemistry to determine the structures of molecules. This test was performed to find out what phase our MnO2 solution is in. To start the test, we first have to place the solution onto a glass piece. After that, we place the piece onto the holder which is located in the middle. Laser beams then shoot out at many angles. During this test, the indicator is set from 20-80 degree with increment of 1.7. In conclusion to the test, we found out that the solution is in its amorphous phase. We will later compare the efficiency between the amorphous phase and the gamma phase with the gas chromatography test.

X-Ray Diffraction

Pictures: X-Ray Diffraction

Tests: Gas Chromatography

First, we inject the gamma phase solution

into the entrance of the column. The carrier

gas carries the sample molecules through

the column. The detector monitors the outlet

stream from the column, and thus the time

at which each component reaches the outlet

and the amount of that component can be

determined. First we injected only the

toluene to find out that it appears at about

1.73 min. Later, we injected toluene and

benzyl alcohol to see the peak height/area.

We found out that it appears around 4.3 min

(Graph 1). Soon, we measured the peak of

the benzyl aldehyde and found out the

detention time was on 3.3 min (Graph 2).

Tests: Gas Chromatography

-1 0 1 2 3 4 5 6 70

0.5

1

1.5

-1 0 1 2 3 4 5 6 70

0.2

0.4

0.6

0.8

1

1.2

<< Toluene + Benzyl Alcohol

<< Toluene + Aldehyde

Tests: Gas Chromatography(Gamma)

Peak Area

Percentage

Benzyl Aldehyde

0.02

1.26 %Benzyl Alcohol 1.57

-1 0 1 2 3 4 5 6 70

0.2

0.4

0.6

0.8

1

1.2

Peak H

eig

ht

Peak Area

% of Conversion = Ap/ As+Ap * 100

(Amorphous)

Peak Area

Percentage

Benzyl Aldehyde 1.49

80.6 %Benzyl Alcohol 0.23

After performing this on the gamma phase solution, we decided to run all the same test again but on the amorphous phase solution. We found out that the amorphous phase solution was more efficient by the conversion formula.

From the results of the experiment, the hypothesis was correct. We were able to perform the catalytic oxidation of benzyl alcohol and obtain the filter solution Benzaldehyde. Some of the errors we might have made during the experiment was during the filtration process and measuring the mass. By not filtering the solution perfectly, we might have left some traces of Benzaldehyde in the filter paper. This could have cause a decrease in mass. To prevent this mistake from happening again we would use more accurate instruments to filter the solution throughout. Another mistake we might have made during the experiment was not obtaining the mass of the solution accurately. During the experiment, we might have lost some of the mass accidentally during the process of massing the solution with a balance. This cause a reduce in mass of the solution. To prevent this mistake from happening again, we would be precise in placing all the solution completely on top of the balance.

Conclusion

By: Joseph and Bam

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