Cyclohexanol from Cyclohexanone Lab Report PDF

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Organic chemistry I lab report...

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Karla Gonzales CHEM 3220.303 Synthesis of Cyclohexanone from Cyclohexanol 09/16/13

Summary: The purpose of this lab is to synthesize cyclohexanone from cyclohexanol by oxidation using hypochlorite as the oxidizing agent. O

OH

Compound

Structure

Cyclohexanol

Molar Mass (g/mol) 100.158

Melting Point (°C) 25.93

Boiling Point (°C) 161.84

Cyclohexanone

98.15

-47

155.65

Sodium hypochlorite

74.44

18

101

Sodium sulfite

126.04

33.4

Decomposes

Sodium hydroxide

39.99

318

1388

Procedure: 1. Add 150 mg of cyclohexanol, 80 mg acetic acid, and 2.3 mL of sodium hypochlorite to a 5 mL round-bottomed flask a. Mixture should be acidic b. Test with pH paper 2. Add thermometer a. Temp should rise to 45 °C 3. When temp begins to drop, remove thermometer, cap flask with a septum 4. Shake vigorously for 3 minutes 5. Place flask in beaker of water at 45°C for 15 min. a. This completes the reaction 6. Destroy excess reagent a. Add 1 or 2 drops of Na2SO3 7. Add 1 drop of thymol blue indicator a. Test pH, should no longer be acidic 8. Add .3 mL of NaOH to neutralize solution 9. Steam distillation

Karla Gonzales CHEM 3220.303 Synthesis of Cyclohexanone from Cyclohexanol 09/16/13

10.

11. 12. 13.

a. Add boiling chip b. Attach to a distilling head, thermometer adapter, and thermometer c. Distil .8 mL of a mixture of water and cyclohexanone Salting out a. Transfer to reaction tube b. Add .1 g of NaCl until most dissolves c. Add .4 mL of ether 2 times to extract d. Pass through drying column and alumina Add boiling chip, simple distillation Cloudy means product is still wet Weigh, percentage yield

Pre Lab Questions: 1. Calculate the millimoles of sodium hypochlorite used in the reaction: 2.3 mL of a 5.25% solution. Compare this value with the quantity of cyclohexanol to be used in the reaction. Would you describe the oxidant as being present in slight excess or large excess? a. The oxidant is present in large excess when compared to cyclohexanol. 2. How would you determine whether you have really neutralized the solution after the addition of NaOH? a. Test the solution with pH paper. Color should be neutral not blue or red. 3. Why is it necessary to add sodium chloride to the steam distillate before carrying out the ether extraction? a. Because it makes it easier to remove the water from in the solution. The “salting out” separates cyclohexanone from water.

Observations and Results:  Solution became cloudy and hot when the reactants were mixed together  We recovered .03 g of cyclohexanol  Percent yield= (.03/98.14)/(.15/100.2)= .2037 * 100= 20.37% Conclusion: The object of this lab was to synthesize cyclohexanone from cyclohexanol by oxidation. The active oxidizing agent used for this reaction was hypochlorite, HOCl. We started with .15g of cyclohexanol, the reactant, and ended with .03g of cyclohexanone, the product. We achieved a 20% yield, which means most of the reactant was not oxidized to the product or some of the product was lost during distillation/extraction. One way to test to see if there is unreacted reactant is to perform an IR spectroscopy on the product. For cyclohexanone one can expect a peak at 1713 cm-1, characteristic of the ketone functional group. For cyclohexanol, one can expect to see peaks at 3340cm-1 and 1068cm-1, characteristic of the H in hydroxyl and C-O bonds in the product.

Post Lab Questions: 1.

How might you use IR spectroscopy to determine whether the reaction is really complete after the suggested time period (15 minutes in warm water bath)?

Karla Gonzales CHEM 3220.303 Synthesis of Cyclohexanone from Cyclohexanol 09/16/13

a. You can use IR spectroscopy to see if the reaction is complete by looking for the signals characteristic of cyclohexanol. You can expect to see signals at 1068 cm-1 and 3340 cm-1. This tells you that there is still cyclohexanol left in the solution, a sign that the reaction has not reached completion. 2.

What other oxidizing agents might be used to efficiently oxidize cyclohexanol to cyclohexanone? a. Other oxidizing agents you can use to oxidize a ketone to an alcohol are: lithium aluminum hydride (LAH) and sodium borohydride (NaBH4).

3.

How might you use 13C NMR and 1H NMR spectroscopy to determine whether your product is contaminated with unreacted cyclohexanol? a. You can compare the signals of the 13C NMR and 1H NMR of cyclohexanone to cyclohexanol. Below are the 13 C NMR spectras of cyclohexanol and cyclohexanone.

Above: Cyclohexanol 13 C NMR Below: Cyclohexanol 1H NMR

Above: Cyclohexanol 13 C NMR Below: Cyclohexanol 1H NMR...