Cyclohexanol Oxidation

This lab's main goal is to analyze diverse items using straightforward distillation, risky reactions, liquid extraction, gas chromatography, and infrared spectroscopy. In essence, the lab aims to show how cyclohexanol can be oxidized to cyclohexanone. The skills in preparative organic chemistry are enhanced in this post. A yield of 82% was obtained for the product. Additionally, one molecule of cyclohexanol yielded one molecule of cyclohexene.
The reactions of the oxidation-reduction are essential in the organic chemistry (Bahi and Dreyer 2012). Evidently, the alcohol’s oxidation for the formation of ketones, carboxylic acids, or the aldehydes is a widely used and fundamental reaction. It is always possible to oxidize the primary alcohols to carboxylic acids or aldehydes (Sugunan and Paul 1998). Conversely, the oxidization of the secondary alcohols results in the formation of ketones. However, it is not possible to oxidize the tertiary alcohols (Eriksson 1988). The reaction of oxidation is exothermal. In other words, such reaction results in the release of the heat to the environment as the process continue (Morlock 2015).

The cooling of the mixture of reaction to room temperature show that the process of reaction is complete (Roth 1993). Nonetheless, it is helpful to check if the oxidizing agent that was added to the reaction is enough. Note that a commercial bleach is not necessarily a constant composition’s chemical reagent. Usually, the product is about 0.74 M (5.25%) of the sodium hypochlorite (Lederer 1982). In this kind of experiment, a paper of potassium iodide-starch is used for checking for any excess agent of oxidization. The presence of the oxidizing agent shows that the test is positive. However, the test is negative if there is no agent of oxidation in the solution. Significantly, the cyclohexanol has a lower solubility in cyclohexanone than in water (Littler and Waters 1959).

Normally, the cyclohexanone forms as a separate layer at the reaction time (Cova 1960). In this case, the use of density helps in determining whether the new layer forms on the bottom (sinks) or the top (floats). Also, the addition of the sodium chloride helps in decreasing the solubility of the cyclohexanone in water (Office 2015). Most importantly, infrared spectroscopy is used for deriving some of the information about the purity and structure of the isolated product (Zimowski 2015). Additionally, the test of 2,4-dinitrophenyl is conducted with the aim of determining the carbonyl group’s presence (Hoare and Waters 1962).

Experimental Procedure

In the first place, an aliquot of distilled water (about 30 ml) was placed into a 100 ml round bottomed flask that was placed on a cork ring. Subsequently, 10 ml of concentrated sulfuric acid was carefully measured in a dry measuring cylinder before slowly adding it to the round bottom flask. At this point, a little acid was gently poured down a glass rod before swirling the flask. This step was repeated to allow for the addition of all the acid. Again, the flask was cooled in a water bath to reduce the temperature below 200C after a thermometer was placed into the mixture.

At this point, two immiscible layers were observed since cyclohexanol is only slightly soluble in water. Next, sodium dichromate dihydrate (10.5 grams) was dissolved in water (5 ml) in a 25 ml conical flask. This solution was then added carefully to the sulfuric acid/ cyclohexanol mixture over approximately 30 to 40 minutes by the use of a dropping pipette. The flask was then swirled vigorously during the process of addition while at the same time maintaining the mixture’s temperature in the round bottom flask between 25 to 35 degrees Celsius.

The reaction mixture was then diluted by the addition of the distilled water (about 10 ml) after adding the oxalic acid to destroy the excess agent of oxidation. Henceforth, the flask was connected to a simple distillation assembly, and the mixture distilled until about 35 ml was collected in the conical flask (receiver). The residue was again poured into the round bottom flask after the apparatus cooled sufficiently. Moreover, the distillate in the conical flask

was transferred to a separating funnel before adding the sodium chloride’s (2 grams portions) solid spatula to the separating funnel. The drying agent was removed by gravity filtration through a fluted filter paper. A pinch of anti-bumping granules was then added to the round-bottomed flask. Finally, the cyclohexanone was distilled slowly into a clean pre-weighed conical flask.

Results and Discussion

The weight of the bottle = 52.25 grams

The weight of the product obtained = 5.08 grams

The total weight of the whole content = 57.33 grams.

The range of boiling = 95 degrees Celsius

Results of the integration

No.

Retention time (min)

Height mV

Area mV*min

Relative height %

Relative area %

Amount n.a.

1

0.772

6.265

0.180

0.10

0.07

n.a.

2

0.868

7.367

0.225

0.11

0.08

n.a.

3

1.002

9.116

0.270

0.14

0.10

n.a.

4

1.318

6446.591

264.257

99.65

99.75

n.a.

Total

6469.340

264.932

100.00

100.00

n.a.



Figure 1: The Formula of the Product Obtained.

In figure 1, the name of the product (HOH) ketone is hydrogen hydroxide. One molecule of cyclohexene is produced by one molecule of cyclohexanol. The mass of cyclohexanol used is 5.08 grams. Therefore, 5.08 grams of cyclohexanol/ 100.2 g/ mole = 0.0507 mole of cyclohexene. When converted to grams, 0.0507 mole x 82.1 g/mole = 4.16 grams of cyclohexene. For this reason, the percentage yield of the product = 4.16 g/ 5.08 g x 100 = 81.89%. The infrared spectrum of the cyclohexanol = 5.08 grams. In the same way, the infrared spectrum of the cyclohexanone = 4.16 grams.

In this case, the purity of the cyclohexanone is about 82%. Also, the formula of oxalic acid is represented as C2H2O4 (Becker and Beattie 1982). Upon the oxidation of the oxalic acid, the product that forms are called hydrogen peroxide (Fridman 2004). Remember, salt is added to the mixture in the separating funnel to oxidize the cyclohexanol into the cyclohexanone. Practically, the boiling point of ethanol and ethanoic acid are -890C and 118.10C respectively (Deitrich 2011). In ethanol, high yield is obtained by using acidified potassium dichromate. Similarly, the use of rhodium/ iodide catalysts produces a high yield (about 98%) of ethanoic acid (Wells and Husain 1970).

Conclusion

Overall, the lab managed to demonstrate the cyclohexanol’s oxidation to the cyclohexanone. It also helped in improving the skills in the preparative organic chemistry. Because the yield is high (82%), it is clear the lab was successful. High yield of ethanol and ethanoic acid are also observed to be increased by the use of acidified potassium dichromate and rhodium/ iodide catalysts respectively.











































References

Bahi, A. and Dreyer, J. (2012). Involvement of nucleus accumbens dopamine D1 receptors in ethanol drinking, ethanol-induced conditioned place preference and ethanol-induced psychomotor sensitization in mice. Psychopharmacology, 222(1), pp.141-153.

Becker, P. and Beattie, J. (1982). Ruthenium catalyzed the oxidation of cyclohexanol. Australian Journal of Chemistry, 35(6), p.1245.

Cova, D. (1960). Vapor-Liquid Equilibria in Binary and Ternary Systems. Cyclohexanol-Phenol, Cyclohexanone-Cyclohexanol, and Cyclohexanol-Phenol-Cyclohexanone. Journal of Chemical & Engineering Data, 5(3), pp.282-284.

Deitrich, R. (2011). Ethanol as a Prodrug: Brain Metabolism of Ethanol Mediates Its Reinforcing Effects - A Commentary. Alcoholism: Clinical and Experimental Research, 35(4), pp.581-583.

Eriksson, K. (1988). Aqueous size-exclusion chromatography (Journal of Chromatography Library, Vol. 40), Journal of Chromatography A, 456, p.450.

Fridman, V. (2004). Dehydrogenation of cyclohexanol on copper-containing catalysts II. The pathways of the cyclohexanol dehydrogenation reaction to cyclohexanone on copper-active sites in oxidation state Cu0 and Cu+. Journal of Catalysis, 222(2), pp.545-557.

Hoare, D. and Waters, W. (1962). 180. Oxidations of organic compounds by cobaltic salts. Part I. The mechanism of oxidation of cyclohexanol and t-butyl alcohol. Journal of the Chemical Society (Resumed), p.965.

Lederer, M. (1982). Ion chromatography. Journal of Chromatography A, 245(3), p.385.

Littler, J. and Waters, W. (1959). 812. Oxidations of organic compounds with quinquevalent vanadium. Part III. The oxidation of cyclohexanol. Journal of the Chemical Society (Resumed), p.4046.

Morlock, G. (2015). Miniaturized planar chromatography using office peripherals — Office chromatography. Journal of Chromatography A, 1382, pp.87-96.

Office, C. (2015). Acknowledgement to Reviewers of Chromatography in 2014. Chromatography, 2(1), pp.19-19.

Roth, M. (1993). Thermodynamic pitfalls in chromatography revisited: Supercritical fluid chromatography. Journal of Chromatography A, 641(2), pp.329-335.

Sugunan, S. and Paul, A. (1998). Basicity and catalytic activity of ZrO2−Y2O3 mixed oxides in the oxidation of cyclohexanol. Reaction Kinetics and Catalysis Letters, 65(2), pp.343-348.

Wells, C. and Husain, M. (1970). Kinetics of oxidation of sec-butanol and cyclohexanol by aquarium(IV) ions in aqueous perchlorate media. Transactions of the Faraday Society, 66, p.2855.

Zimowski, A. (2015). Purification of cyclohexanol from cyclohexane oxidation Oczyszczanie cykloheksanolu uzyskiwanego w process utleniania cykloheksanu. PRZEMYSŁ CHEMICZNY, 1(5), pp.101-105.