The purpose of the lab experiment was to use steam distillation to extract pure clove oil from ground cloves. In addition, infrared spectroscopy was used to analyze and identify the main component in the clove oil. Initially, the extraction process involved transferring the clove oil from the ground cloves into a water solution on day one. Then, DCM (Dichloromethane) was used to separate the oil from water. The resulting sample was then sealed in a container for one week before being dried and having DCM removed. Finally, IR spectroscopy was used to analyze the clove oil.
The steam distillation apparatus was prepared, activating the water in the distilling column. 5.000 g of ground clove were obtained and placed into a 500 mL round bottom flask. Additionally, 50.0 mL of distilled water were acquired and added to the same flask. Furthermore, 100.0 mL of distilled water were obtained and added to the separatory funnel. The Bunsen burner was connected to the gas line and turned on before being ignited for coating the bottom of the round bottom flask, containing water and ground cloves, with a “paint” stroke.
The solution was heated to medium boiling. The vapors traveled up into the distilling head and accumulated in the distilling column. The distillate was collected in a 250 mL flask. The solution was heated until approximately 100 mL of distillate was collected in the receiving flask, and the distillate was mostly clear and odorless. The gas and Bunsen burner were turned off. The steam distillation apparatus was allowed to cool and disassembled. The distillate was poured into a clean, dry separatory funnel. Then, 20.0 mL of DCM was added to the separatory funnel.
The solution in the separatory funnel was mixed by capping and inverting it, allowing the gas to be released from the top. The bottom layer of the separatory funnel was collected in a 50 mL flask. Another 20.0 mL of DCM was added to the separatory funnel and inverted again, and its bottom layer transferred to the same 50 mL flask. The flask was sealed with a cork stopper and parafilm, and placed in a cabinet for one week.
In the analysis of Clove Oil, the clove oil/DCM mixture was added to the separatory funnel along with 15.0 mL of 1M aqueous sodium hydroxide.
The contents from the bottom layer of the separatory funnel were transferred to a 250 mL beaker, while the top layer was returned to the separatory funnel. Then, 15.0 mL of 1M aqueous sodium hydroxide was added back into the separatory funnel. The bottom layer was removed again and the top layer was moved back to the previous 250 mL beaker. After that, a mixture of 10 mL of hydrochloric acid with clove oil resulted in cloudiness. A portion of this mixture was placed on blue litmus paper and turned pink, indicating acidity. The acidic solution was then combined with the separatory funnel and mixed with 15 mL of DCM (dichloromethane). The bottom layer from the separatory funnel was transferred to a 250 mL beaker, followed by adding another 15.0 mL of DCM to the separatory funnel. Once again, the bottom layer was transferred back to the 250 mL beaker. For this process, a round bottom flask weighing 104.356 g along with a cork base were used. Magnesium sulfate was added to the beaker until it no longer formed clumps when stirred together with other substances present in it. The liquid above these solid clumps (supernatant) was poured into a pre-weighed round bottom flask (100mL capacity). Next, using a rotovap machine, DCM from this solution underwent an evaporation process until only clove oil remained in round bottom flask along with cork base which weighed at final weight value of105 .426 g after all processes were completed
The clove oil was added to the IR spectroscopy machine and run. The results were obtained (Figure 1) and analyzed to find the major constituent. The weight of clove oil obtained was calculated at 1.070 g and the percent recovery was calculated at 21.4%.
Calculations: The weight of clove oil obtained was found using the following equation. Weight of 100 mL round bottom flask, cork base, and clove oil – weight of 100 mL round bottom flask and cork base = weight of clove oil obtained (105.426 g – 104.356 g = 1.070 g). The percent recovery was found using the following equation. Weight of clove oil (g) / mass of ground cloves (g) x 100% = percent recovery of clove oil (1.070 g / 5.000 g x 100% = 21.4% recovery of clove oil).
Results and Discussion: Upon obtaining the purified sample of clove oil, which accounted for about 21.4% recovery from the ground cloves, the IR was analyzed. The peaks on the IR that helped in determining the identity of the major constituent of clove oil were located at the points: IR (film): ? = 3515, 3075, 1650, 1515, 1270 cm-1. The chemical equation for the major constituent was known to be C10H12O2 which accounts for 6 possible combinations to create compounds.
The analysis of the IR showed various peaks indicating specific bonds. The peak at 3515 cm-1 showed an O-H bond, eliminating four possibilities. Another significant peak at 1515 cm-1 indicated aromatic C=H bonds, identifying a benzene ring in the compound. Moreover, peaks at 1650 cm-1 suggested C=C bonds between Csp2 molecules (Figure 1). Using the IR analysis, eugenol was identified as the primary component of clove oil (Diagram 1).
The experiment compared the IR of clove oil (Figure 1) to the known IR of eugenol (Figure 2), revealing similarities except for differences in the O-H peaks. Figure 1 displayed a short wide O-H peak, while Figure 2 showed a medium thin O-H peak. The recovery rate of clove oil from ground cloves was only 21.4%. This low percentage could be due to some clove oil not being extracted from the DCM/clove oil mixture left for one week. Additionally, the mass of the ground cloves would be higher as they contain more than just clove oil.
In this lab, the main objective was to ensure a high level of purity, even if it resulted in a lower percent recovery. The conclusion drawn from the experiment was that eugenol was identified as the major constituent of the obtained clove oil through steam distillation. Despite a low percent recovery, it was confirmed that the sample of clove oil was pure and eugenol was indeed the major component.
