Adipic acid from cyclohexanone PDF

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CHEM250 Section 18935

Adipic acid from Cyclohexanone Name: Shahid Waseem Date: 04-20-20 1. Purpose (5pts) The purpose of this experiment was to synthesis adipic acid through oxidation of cyclohexene with Potassium permanganate. Alkenes can easily be oxidized by potassium permanganate and other oxidizing agents.

2. Balanced equation (10pts)

Name of Chemical

Cyclohexanone

Adipic Acid

Name

Cyclohexanone

Adipic Acid

Formula

C6H10O

C6H10O4

Molar Mass

98.15 g/mol

146.1412 g/mol

Melting Point

-23.8 ºC

151-154 ºC

Boiling Point

155.6 ºC

265 ºC

3. Procedure and observation (10pts) 3.1) Mix 2.6 ml cyclohexanone and 7.5g permangnanate with 67 mL of water in a 250-mL Erlenmeyer flask, adjust the temperature to 30 0C, note that there is no spontaneous temperature 1

CHEM250 Section 18935

rise, and then add 0.5 mL of 3M sodium hydroxide solution. A temperature rise is soon registered by the thermometer. Permanganate partially dissolves and reacts with the cyclohexanone. Slow and steady increase the temperature.

3.2) When the temperature reaches 45 0C (15 min) slow the oxidation process by brief icecooling and keep the temperature at 45 0C for 20 min. Wait for a slight further rise (47 0C) and an eventual drop in temperature (25 min), and then heat the mixture by swirling it over hot plate to complete oxidation and to coagulate the precipitated manganese dioxide. When reaction reached 45 Celsius it turned slightly brown. Reaction turned more brown and yellow after reheating and temperature will rise again.

3.3) Make a spot test by withdrawing reaction mixture on the tip of a stirring rod and touching it to a filter paper; permanganate, if present, will appear in a purple ring around the spot of manganese dioxide. We will add a drop of the reacted mixture to a separate beaker of water and no purple permanganate, saying reaction was completed.

3.4) If permanganate is still present, add small amounts of sodium bisulfite until the spot test is negative. The sodium bisulfate remove the traces of permangnate.

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CHEM250 Section 18935

3.5) Then filter the mixture by suction on an 11cm Buchner funnel, wash the brown precipitate well with water (20 mL), add a boiling chip, and evaporate the filtrate from a large beaker to a volume of 17.5 mL. There was brown residue present. We will filter the mixture to where the red potassium salt was the filtrate and brown residue was left behind.

3.6) Acidify the hot solution with concentrated hydrochloric acid to pH 1-2, add 2.5 mL acid in excess, and let the solution stand to crystallize. The bubbling trait is where the dioxide is reacting with the alkalide. The red potassium salt turned yellow. The pH was very strong.

3.7) Collect the crystals on a small Buchner funnel, wash them with a very small quantity of cold water, press the crystals between sheets of filter paper to remove excess water, and set them aside to dry. A typical yield of adipic acid, mp 152-153oC, is 1.75g When white crystals formed we did another set of filtration where the residue is the adipic acid.

4. Results and Explanation (20 pts) In this reaction, the raw materials are 2.5g of cyclohexanone and 7.5g of potassium permanganate, what is the percentage yield if you got 1.2g final product? List at least two possible reasons which could result low yield. At first we combined 2.6 mL of cyclohexanone and 7.5 permanganate and turned into a purple solution. The solution became brown after oxidation and when it was filtered that solute came out clear. Once the solution was brought to a boil and then HCl was added the precipitate turned

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CHEM250 Section 18935

white and crystals. The weight of crystals collected was .100 g. Percentage yield.1001.75 ×100=5.71%.

5:Conclusions (5pts) The expected mass of adipic acid which was expected to be 1.75 g, after the oxidation process was completed but a mass of .100g was obtained, which is a percentage yield of 5.71%. Human error may have been involved as we didn't have enough adipic acid crystals which were obtained reducing the overall yield. Human error can alter the outcome of this experiment.

6:Post lab questions (30pts) 1) After the reaction, when withdrawing reaction mixture on the tip of a stirring rod and touching it to a filter paper, it appears in a purple ring around the spot of dark, what does it mean? What does it contain in the purple ring, what in the dark spot? How to get rid of the purple ring?

If the purple ring appears potassium permegnate is still present. To get rid of the purple ring we will add drops of sodium bisulfate to the solution until the test becomes negative. The dark spot that appears is manganese dioxide.

2) Anna has two bottles containing adipic acid and cyclohexanone respectively. She forgot to label the name on the bottles. Thus, she decided to use IR spectroscopy to identify which one is which. The spectra are shown below, pls help her to identify them and explain. 4

CHEM250 Section 18935

The first graph represents the bottle of adipic acid because the absorbance chart is shows the light transmittance is at 1700 where its an carboxylic acid based off last week chart. The second graph shows a transmittance of 1750 which can indicate ketones are present and can identify the presence of cyclohexanone.

A

B

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