Page |1 Myeeka Hammond June 7,2017 Isolation of Eugenol from Cloves by Distillation Purpose: The purpose of the experiment is to use distillation to extract an essential oil, specifically Eugenol oil, from a plant, the clove. Introduction: Essential oils are components of various compounds and are associated with scents and medicinal purposes. Essential oils can be found in cloves, between 14% and 20% by weight and its primary essential oil being eugenol, C10H1202. Eugenol, molecular formula shown in figure 1, has been known to serve as a food flavoring additive and a dental anesthetic. Most oils are found to have long hydrocarbons. Essential oils, however, are complex mixtures of fluids with a low viscosity that also contains a variety of molecular species and functional chemistry groups. Cloves are the flower buds from a tropical tree that grows in the Spice Islands of Indonesia and the islands of the Indian Ocean. In this experiment, Steam distillation is used to extract essential oils, eugenol, from crushed cloves. Steam distillation is utilized because of the oils high boiling points, which makes it difficult to extract completely. When using steam distillation. The spice or herb is suspended in water, and as the water is boiled and vaporizes, it extracts the essential oils and carries them over into the graduated cylinder. The boiling point of eugenol is 225°C but it is insoluble in water so it will steam distill at a temperature slightly lower than the boiling point of the water. Figure 1: Eugenol Chemical Structure
Page |2 Myeeka Hammond June 7,2017 Isolation of Eugenol from Cloves by Distillation Materials: 1. 2 Grams of cloves 2. 50 mL round bottom flask 3. 3 boiling chips 4. Heating mantel 5. Simple Distillation Apparatus 6. 25 ml graduated cylinder 7. 5 ml of Dichloromethane (CH2Cl2) 8. Anhydrous Magnesium sulfate (MgSO4) 9. Seperatory funnel 10. 2 Watch glass 11. 3 clips 12. IR spectrum Machine Procedure: The experimenters obtained 2 grams of cloves, that were pre-grinded, and added them into a 50-mL round bottom flask and added three boiling chips along with 25-mL of water. The solution was then swirled the flask, which aided in wetting the cloves, and then left the flask to sit for about 10 minutes before beginning the distillation. While waiting for the ten minutes, the experimenters set up the simple distillation apparatus and greased all the parts that were attached to ensure that it was sealed. They then used the heating mantel to heat the flask to a boil and the vapor will start to distill over the collection vessel. The distillation was continued for about 45 minutes or until 12-15 mL of the condensation in the graduated cylinder was collected. After the distillation was completed, the experimenters allowed it to cool to room temperature. Once it was cooled, the experimenters extracted the eugenol from water using dichloromethane in a speratory funnel. This was done by adding 5mL of the dichloromethane, shaking the funnel to mix the layers and then it was separated by opening the cockstop to remove the lower layer, which is the CH2Cl2. The experimenters then repeated this separation process again and then dried the CH2Cl2with about one gram of anhydrous Magnesium
Page |3 Myeeka Hammond June 7,2017 Isolation of Eugenol from Cloves by Distillation Sulfate. After it was transferred, the dried dichloromethane solution onto two tared watch glasses, then rinsed it a little with CH2Cl2 and then allowed it to evaporate in the fume hood to isolate the eugenol oil. Once the oil was obtained, it was weighed to get the mass and then found the IR spectrum using the IR machine. Calculation: Percent yield = Grams of Eugenol/ Grams of clovers used X 100
Data and Observations: The calculated percent yield of 0.00% is relatively low. A possible explanation for this low yield may have arose from an inadequate amount of dichloromethane during the extraction method. The dichloromethane would help spate the eugenol and the water. Eugenol is more soluble in dichloromethane than in water, and it would be found in the organic layer with dichloromethane. Other than the low percent yield, the experiment proceeded as planned. There were no spills or other abnormal physical losses. Some observations that my group members and I observed through-out the experiment is that right before the solution in the round bottom flask started boiling all the cloves started to club together and settle at the bottom of the flask. One thing was really cool to me was that you could see the distillate running through the condenser, most likely because it is not the same color as the water in there, and out in the graduated cylinder. The color of the distillate was a cloudy white solution that eventually resulted in the eugenol oil.
Page |4 Myeeka Hammond June 7,2017 Isolation of Eugenol from Cloves by Distillation Conclusion: The result of this experiment showed that 0.00% of oil could be recovered from cloves by steam distillation. The takeaway from this lab experiment was to learn the techniques of isolation of natural products, which included steam distillation, drying organic solution, and liquid/liquid extraction. It is possible that the ratio of the size of the glassware to the theoretical amount of eugenol (which was obtained from the cloves in this experiment) is large which lead to a large percentage of the product on the sides of the glass apparatus. If this is the case of our low percent yield, then further experiments should include a larger sample of cloves for better/ improved recovery. Otherwise, it can be concluded, from this specific experiment, that the specific sample of cloves used contains approximately 0.00% of eugenol. Post lab questions: 1. Calculate the percent (by mass) of eugenol in cloves based on your data. Eugenol typically makes up about 15-20% of the mass of clove buds. Discuss reasons why you may not have isolated this amount, and propose ways to increase your yield. 2. Examine the IR spectrum of eugenol, and identify the signals for the major functional groups. 3. A representative of 1H NMR spectrum of eugenol is shown below. Assign the signals to the correct protons in the structure. 4. Eugenol can also be isolated from cloves using extraction with CO2. Discuss the advantages and disadvantages of distillation verses CO2 extraction. Distillation is more advantageous than carbon dioxide extraction because a larger product yield is extracted. However, it takes time. Carbon dioxide extraction is also disadvantageous because the pressure that builds up from sublimation can cause the cap on the test tube to come off.
