Virtual Lab - Extraction of Eugenol PDF

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Chemistry 255 College of the Canyons

Extraction of Eugenol Online Version

Name ________________________

Extraction of Eugenol Learning Goals The purpose of this experiment is to: 1. 2. 3. 4. 5.

Apply general distillation concepts to steam distillation. Apply general extraction concepts to the isolation of eugenol from cloves. Calculate a percent recovery of eugenol. Predict splitting and then analyze the 1H NMR spectrum of eugenol. Analyze the IR spectrum of a crude mixture.

Introduction For a general review of extraction, use the following links: https://youtu.be/5CVdbCSLYTA and https://youtu.be/DmvaOb1xb1o For a general review of distillation, use the following link: https://youtu.be/GtuMlWMajtw For a general overview of 1H NMR spectroscopy, use the following link: http://ochem.com/tutorials/spectroscopy-part-4-1h-nmr.html Essential oils are mixtures of highly aromatic compounds extracted from a variety of botanical materials – tree bark, flowers, and grasses. Essential oils have a long history of use in traditional medicines including treatment for minor aches, congestion, and therapeutic applications for anxiety and insomnia. They are not oils (long chained hydrocarbons) but are low viscosity fluids containing many molecular species and functional groups. Eugenol, the main component of clove oil, is used in dentistry as a local anesthetic and antiseptic. It is a pale, yellow liquid with a smell of bay leaves and cloves. Eugenol is a substituted methoxy phenol compound, similar to vanillin, but with an allylic functional group in place of the aldehyde in the para position as shown in Figure 1. The allylic chain gives eugenol its characteristic strong odor.

Figure 1. Structure of eugenol, a component of clove oil Page 1 of 8

Chemistry 255 College of the Canyons

Extraction of Eugenol Online Version

When two immiscible compounds are distilled, the vapor of each component is generated independently of the other component. This process is called co-distillation. When one of the compounds is water, the process is called steam distillation. In a steam distillation, the total vapor pressure, PT, above the immiscible liquids is equal to the sum of the vapor pressure of each component. This allows distillation to be run at lower temperatures, below the boiling points of the individual components. For example, the vapor pressure of pure water at its boiling point of 100 ºC is 760 mmHg, or 1 atm. Because the eugenol will also contribute to the total vapor pressure, a mixture will distill at a temperature less than 100 ºC. Steam distillation offers the advantage that volatile compounds, such as eugenol (bp 254 oC), can co-distill with water at relatively low temperatures. In this experiment, you will observe the steam distillation to separate components of a clove-water mixture. Since the oils are immiscible in water a cloudy, white solution is collected. The hydrophobic eugenol is then extracted with methylene chloride (dichloromethane) and dried over anhydrous sodium sulfate.

Pre-lab Review the extraction of eugenol flowchart. Note that you do not have to submit anything for this section beforehand.

Lab Demonstration Questions 1. What is the purpose of a steam distillation? (Why are we doing it, and how does it work?) Draw the set-up.

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Chemistry 255 College of the Canyons

Extraction of Eugenol Online Version

2. What is the purpose of the addition funnel?

3. What is the boiling point of eugenol? (Does that match the temperature on the distillate, and how does that relate to question #1?)

4. Why do you think the distillate has a cloudy white appearance? (What is in the mixture you are collecting?)

5. When dichloromethane is added, is the organic layer on bottom on top? Think about what value you can use to determine this.

6. The combined organic layers are mixed with two portions of 5% aqueous NaOH. During this step, is the eugenol in the organic or aqueous layer? Use the structure of eugenol (Figure 1) to show the reaction (and mechanism) happening during this step.

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Chemistry 255 College of the Canyons

Extraction of Eugenol Online Version

7. What is the purpose of neutralizing the aqueous layer? Draw the reaction (and mechanism) happening during this step. Refer to question 6.

8.

Why do the combined aqueous layers turn cloudy/form precipitate as the acid is added?

9. The acidified aqueous layer is mixed with two portions of dichloromethane. During this step, which organic compounds are present (eugenol and/or eugenol acetate), and in which layer, organic or aqueous? Briefly explain.

10. How do you properly remove grease from the glass joints? Briefly explain.

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Chemistry 255 College of the Canyons

Extraction of Eugenol Online Version

Post-lab 1. Use the data in Table 1 (page 6) and your assigned element to calculate the percent recovery of eugenol. Remember to show your work. Your assigned element: _____

% Recovery: _____________

2. Predict the splitting pattern for each labeled proton (1H NMR spectrum).

3. Use the provided spectrum to assign all signals on the 1H NMR (label A-I) spectrum shown in Figure 2 (page 7). Show your work. Write directly on the spectrum. 4. The “crude eugenol extracts” IR spectrum analyzed the dichloromethane extracts before treatment with aqueous NaOH. Is there any evidence of eugenol acetate in the IR spectrum? Explain. See Figure 3 (page 8).

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Chemistry 255 College of the Canyons

Extraction of Eugenol Online Version

Table 1. Data for percent recovery calculation your element H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe

mass of cloves used (g) 14.2368 12.01854 16.8569 10.0252 17.0563 13.2067 14.5276 15.6384 12.3625 18.9652 13.6389 14.8523 16.5682 14.9826 15.4283 12.3685 17.8529 12.3695 13.4285 11.2585 10.6472 16.9524 16.2854 15.3624 18.8542 15.2534

mass of eugenol recovered (g) 0.8536 0.7258 1.06854 0.6385 1.3682 0.8536 0.9637 0.9685 0.6385 1.6982 0.7528 0.7452 1.2058 0.8523 0.8719 0.3682 2.0685 0.8726 0.7425 0.6328 0.5938 1.3085 1.0985 0.8932 1.6274 0.9638

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Chemistry 255 College of the Canyons

Extraction of Eugenol Online Version

Figure 2. 1H NMR spectrum of eugenol

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Chemistry 255 College of the Canyons

Extraction of Eugenol Online Version

Figure 3. IR spectrum of eugenol “crude” extracts

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