Isolation of Eugenol from cloves by Distillation PDF

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Lab report regarding steam distillation...

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1

Isolation of Eugenol from cloves by Distillation

Name: Cristian Acuna Vasquez Date : October 13th, 2020 Class: CHM 2210 L Professor: Dr. Rajendra Shakya

2 Purpose The purpose of this the experiment is to try to isolate Eugenol from cloves by steam distillation.

Introduction Natural aromatic compounds and essential oils are components of various substances that are associated with scent and medicinal purposes. One particular essential oil found in cloves is eugenol. Eugenol has been known to serve as food flavoring additive and dental anesthetic. These essential oils are complex mixtures of fluids with a low viscosity that also contain a variety of molecular species and functional group chemistry and are found to have long chains of hydrocarbons . In this experiment, steam distillation will be used as the separation process to purify or isolate temperature-sensitive materials, such as these essential oils. Steam or water is added to the distillation apparatus, lowering the boiling point of the compounds; The goal is to heat and separate the components at temperatures below their decomposition point. Steam distillation is useful for the purification of organic compounds. When organics are distilled, the vapor is condensed. Because water and organics tend to be immiscible, the resulting liquid generally consists of two phases: water and the organic distillate. After the steam distillation, a extraction is required through a separatory funnel and an organic solvent, in this case will be dichloromethane to isolate the eugenol. A drying agent such as anhydrous magnesium sulfate can be used to help removed any moisture left in the sample. An IR spectrum ( infrared spectroscopy) will be used on the sample to identify that it is Eugenol. Procedure : 2.056 grams of crushed Cloves were obtained and put into a 50 mL round bottom flask with a boiling chip and 25mL of water. The flask was swirled and sat for 10 minutes while the

3 distillation apparatus was set up. The flask was placed on the distillation apparatus, the heating mantle was heated and the water was turned on. The solution was heated to boiling point until 10-12mL of distillate was collected. The distillate was then left to cool to room temperature. Then 5 mL of dichloromethane was added with the distillate and it was shaken. A pipet was used to remove the dichloromethane. The extraction was repeated with fresh dichloromethane and was combined with previous extraction. The dichloromethane layer was then dried with anhydrous magnesium sulfate. The dried solution was then transferred to a watch glass and was placed in the hood to evaporate and isolate the eugenol. The mass was then obtained and the IR spectrum.

Table of reagents 1. Eugenol Formula: C10H12O2 MW: 164.20 g/mol BP: 254 C Density: 1.06 g/cm3 Physical Description: colorless oily liquid 2. Magnesium Sulfate Formula: MgSO4 MW: 92.14 g/mol BP: 111 C Density: 2.66 g/cm3 Physical Description: white crystalline solid 3. Methylene Chloride Formula: CH2Cl2 MW: 84.93 g/mol BP: -97 C Density: 1.33 g/cm3 Physical Description: clear colorless liquid

Data and Observations:

4 Once the crushed cloves and water mixed together, a heterogenous solution was formed. The solution started dripping after 47 minutes and 12 mL of distillate was collected. The distillated is white in color. Mass of Crushed cloves : 2.056 g Watch glass mass #1 : 44.068g Watch glass mass #2 : 44.051g Watch glass mass plus eugenol # 1 : 44.117 g Watch glass mass plus eugenol # 2 : 44.082 g Mass of Isolated Eugenol: 0.08g Percent Yield: 0.08/2.056 g x 100 = 3.89 %

Discussion: Steam distillation is typically considered the best way to obtain essential oils. However, this method produces varying oil qualities dependent upon the temperature, pressure and time used for distillation. In practice, most essential oils are obtained by distillation at rather elevated temperature, in order to optimize the yield. The extraction solvent employed was dichloromethane. Generally, for complete extraction it is necessary to repeat the process several times in order to obtain an acceptable yield. The main disadvantage of this method is that, after the extraction, the solvent needs to be evaporated, which causes heat degradation of the eugenol. At the end of the process the residual solvent concentration is lowered. Some sources of error that could had happened was not having grounded the cloves well enough, may not have distilled the cloves long enough in high heat, and may have had loose connectors between the glassware that would account for a lower percent yield. Also, the distillation rate may have been too fast which could lead to the collection of a less pure distillate, and subsequently a higher percent recovery than the actual value. Generally it is estimated that cloves contain approximately

5 between 14 % to 20 % of the essential oil and only half can be isolated. At the end of the experiment, the percentage yield was 3.89 %. Conclusion: In conclusion, this experiment was successful at teaching the students the techniques of isolation of natural products. This techniques will include tasks like the importance of steam distillation, drying organic solutions, liquid/liquid extraction and infrared spectroscopy. In this experiment, it was shown that about 3.89% of an oil could be recovered from cloves by steam distillation. This oil was identified as eugenol by comparison of its infrared spectrum with a sample. Steam distillation of cloves produced 0.08 g of an oil, which contained in its IR spectrum the functional groups O-H (at 3509.86 cm-1), and alkene C=C (at 1637.79. cm-1) The IR spectrum is attached to this report and 0.08g of eugenol was recovered from 2.056 g of cloves.

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. Percent Yield: 0.08/2.002g x 100 = 3.89 %. There could be many reasons why the percentage yield is 3.89% Some of them include not having grounded the cloves well enough, may not have distilled the cloves long enough in high of enough heat, and may have had loose connectors between the glassware. 2. Examine the IR spectrum of eugenol. And identify the signals for the majors functional groups. OH - at 3509.86 cm-1, C=C at 1637.79. cm-1.

6 3. A representative H 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 versus CO extraction.

With distillation a larger percent yield is obtained versus extraction with carbon dioxide. But with extraction with carbon dioxide the quality of the essential oils are better than with distillation

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