Lab Report #1 Cyclohexanal PDF

Preview

Summary

Lab Report ...

Description

Lab Report Experiment 4.2 TITLE: INTERCONVERSION OF 4-tert-BUTYLCYCLOHEXANOL AND 4-tertBUTYLCYCLOHEXANONE CITATION: Mohrig, J. R., & Schatz, P. F. (2019). Experiment 31: Interconversion of 4-tertbutylcyclohexanol and 4-tert-butylcyclohexanone. C. Hammond (Ed.), Modern Projects and Experiments in Organic Chemistry Miniscale and Williamson Microscale (pp. 240-244). New York, NY: W.H. Freeman and Company. PURPOSE: Investigated two oxidation-reduction reactions involving the interconversion of a mixture of cis- and trans-4-tert butyl cyclohexanol and 4-tert-butylcyclohexanone. Definitions: 4-tert-butylcyclohexanol: may be an irritant. Wash thoroughly after handling. 4-tert-butylcyclohexanone: may be an irritant. Wash thoroughly after handling Sodium borohydride: harmful if swallowed, inhaled, or absorbed through the skin. Avoid breathing the dust. Avoid contact with skin, eyes, and clothing. It decomposes to flammable, explosive hydrogen gas. Diethyl Ether: extremely volatile and flammable. Use it in a hood, if possible. Be sure that there are no flames in the laboratory and no hot electrical devices in the vicinity while you are pouring ether or performing extractions.

Introduction: In this experiment there was a use sodium hypochlorite to oxidize the 4-tert-butylcyclohexanols in the first reaction. In the second reaction we used sodium borohydride to reduce 4-tertbutylcyclohexanone. Oxidation-reduction reactions are extremely diverse, and they proceed by a variety of mechanisms. The unifying factor is that one substrate is oxidized, and another is reduced. For the oxidation part of this experiment we will look at the oxidation of a secondary alcohol to a ketone using an oxidizing reagent. The thin layer chromatographic technique will be used to watch the progress of the oxidation reaction.

Sodium hypochlorite solutions are sold in the store. There are many places in people’s lives that sodium hypochlorite is excessively used. An example of this usage is the sanitization of a swimming pool. There is a less concentrated product available in stores and we know this as the typical household bleach. The oxidizing

agent that was used in this experiment is (Cl)^+ and is then reduced to (Cl)^-. This oxidation procedure is better than the others because it does not require an efficient agitation.

Next is the reduction of a ketone. This was done by using sodium borohydride. Sodium borohydride is a mild reducing agent. The Thin-Layer Chromatography will be used to watch the progress of the reaction. Sodium borohydride is commonly used to reduce ketones and aldehydes. The reasoning for sodium borohydride being used is because it is a much slower reaction than other reducing reagents.

Mechanism of the reduction of 4-tert-butylcyclohexanone:

Experimental In the experiment 4.2 the reduction reaction is what is being performed. The miniscale procedure can be found of page 240-243. Dissolve 0.80 g of 4-tert-butylcyclohexanone in 6.0 mL of 95%

ethanol in a 50 mL Erlenmeyer flask. Slowly add 0.60 g of sodium borohydride. After 15 minutes check for completeness of the reaction by the TLC method. When the reaction is complete add 10 mL of water and then carefully add 3 M hydrochloric acid solution in 1 mL portions. Heat the mixture to a boiling point. Cool the mixture to room temperature. Add 15 mL of diethyl ether and stir the mixture. Working in a hood you should shake the mixture and drain the lower aqueous layer into a labeled flask. Pour the ether layer into another labeled flask. Return the aqueous phase to the separatory funnel and extract it a second time with. 10mL of ether. Wash the combined layers with two 10mL portions of water. Transfer the ether solution to a dry 50mL Erlenmeyer flask. Dry the ether/product solution with anhydrous magnesium sulfate. Filter the product solution into a tared 50mL Erlenmeyer flask using a fluted filter paper and evaporate the ether one steam bath. Weigh the product after all the ether has been removed and calculate the percent yield. Data/Results Mass of round bottomed flask without product: 36.12 g Mass of round bottomed flask with product: 36.73 g Mass of product collected: 0.61 g From this mass the percent yield of cyclohexanone could be determined: 0.80 grams 4-tert-butylcyclonexanone/ 154.2MW= 0.0052mol cyclohexanone 0.0052mol cyclohexanone x 156.3 MW=0.8109 g cyclohexanol The actual yield: 0.61 g The theoretical yield: 0.81 g Percent yield: 0.61/ 0.81 x 100= 75.3%

IR spectrum of cyclohexanol provided by the TA:

Discussion The percent yield was around 76% percent so the reaction can be considered successful. A precise reaction should be above 80%. There are some human errors and scientific errors that could have affected the percent yield. An example of a couple of these would be that not all of the cyclohexanone reacted, and another would be that some was lost in the transfer of layers. After looking at the IR spectrum that was given by the TA the difference in the cyclohexanol and the cyclohexanone is the alcohol. When looking at the cyclohexanone the peak is around 3000 and is narrower and sharper. In the cyclohexanol the peak that is around 3000 actually contains two wider peaks. Looking at the IR spectrum we can determine if cis and trans cyclohexanols were produced. This is determined by looking at the IR spectrum and seeing what their peaks look like. If they are similar to the cyclohexanol shown, although the peak may be slightly higher than 3000. Conclusion In conclusion 4-tert-butyl cyclohexanone was reduced by sodium borohydride to form cis and trans 4-tert-butylcyclohexanol in good yield. The main goal of the experiment was to have the products contain an alcohol group and form 4-tert-butylcyclohexanol and by looking at the data it shows that the experiment was successful. Reducing cyclohexanone with sodium borohydride back to either the cis or trans cyclohexanol was achieved. Post Lab Questions:

Question 1: By using the IR we are able to check for the presence of unreacted material. The borad band that is at 3300cm- 1 represents the alcohol functional group that is for 4-tert-butylcyclohexanol. Question 2: The oxidation of 2-propanol produces acetone. This is technically not a contaminant because it is already present. The reason for it being present is because it is used as a solvent in the reaction, it is removed by rotary evaporator. Question 3: The oxidation of cis-2-methylcyclohexanol with NaOCl will produce 2methylcyclohexanone as the product....