The purpose of this lab was to obtain a pure sample of clove oil from ground cloves using steam distillation, perform infrared spectroscopy on the sample, and analyze the IR to identify the major constituent in the clove oil. The first day the clove oil was removed from the ground cloves into an aqueous solution then removed from the water using DCM. The sample was left in a sealed container for one week and then isolated by drying the sample and removing the DCM. After the clove oil was isolated it was analyzed using IR spectroscopy.
Experimental. Isolation of Clove Oil: The steam distillation apparatus was assembled and then the water in the distilling column was turned on. 5. 000 g of ground clove was obtained and added to the 500 mL round bottom flask. 50. 0 mL of distilled water was obtained and added to the same 500 mL round bottom flask. 100. 0 mL of distilled water was obtained and added to the separatory funnel. The Bunsen burner was attached to the gas line and the gas was turned on. The Bunsen burner was lit and then used to “paint” the bottom of the 500 mL round bottom flask with water and ground cloves in it.
The solution was heated to a medium boil. The vapors began to travel up into the distilling head and then began to accumulate in the distilling column. The distillate was collected in a 250 mL flask. The solution was heated until around 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 then disassembled. The distillate was poured into a clean, dry separatory funnel. 20. 0 mL of DCM was added to the separatory funnel.
The separatory funnel was capped and inverted allowing the solution to mix and the gas was released from the top. The bottom layer of the separatory funnel was collected in 50 mL flask. 20. 0 mL of DCM was again added to the separatory funnel and then inverted. The bottom layer of the separatory funnel was added to the same 50 mL flask. The flask was then labeled sealed using a cork stopper and parafilm. The flask was set in a cabinet for one week. Analysis of Clove Oil: The clove oil/DCM mixture was added to the separatory funnel. 15. 0 mL of 1M aqueous sodium hydroxide was added to the clove oil in the separatory funnel.
The bottom layer of the separatory funnel was removed and the top layer added to a 250 mL beaker. The aqueous bottom layer was then added back to the separatory funnel. 15. 0 mL of 1M aqueous sodium hydroxide was added to the separatory funnel. The bottom layer was again removed and the top layer added to the previous 250 mL beaker. 10 mL of hydrochloric acid was added to the clove oil mixture which turned cloudy. A sample of the mixture was placed on the blue litmus paper which turned pink. The acidic solution was then added to the separatory funnel and 15. mL of DCM was added. The bottom layer of the separatory funnel was added to a 250 mL beaker. 15. 0 mL of DCM was added again to the separatory funnel. The bottom layer was again added to the 250 mL beaker. A 100 mL round bottom flask and cork base were weighed at 104. 356 g. Magnesium sulfate was added to the beaker until the powder stopped clumping together. The supernatant was decanted off into the pre-weighed 100 mL round bottom flask. The DCM was removed from the solution using a rotovap machine. The clove oil, round bottom flask, and cork base were weighed at 105. 426 g.
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. ass of clove oil (g)mass of ground cloves (g)?100%=% recovery of clove oil 1. 070 g5. 000g?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.
When analyzing the IR, the first peak at 3515 cm-1 told me the compound contained an O-H bond which removed four of the six choices. The most prominent peak at 1515 cm-1 told me that the constituent contained aromatic C=H bonds which helped to identify that the constituent had a benzene ring. The peaks occurring 1650 cm-1 showed the constituent contained at least one C=C bond between Csp2 molecules (Figure 1). After elimination the last choice of the compounds using the IR, the major constituent of clove oil was identified as eugenol (Diagram 1). Diagram 1.
The IR of the experimentally obtained clove oil (Figure 1) was then compared to the known IR of eugenol (Figure 2), which was relatively similar except for the short wide O-H peak in figure 1 and the medium thin O-H peak in figure 2. The percent recovery of clove oil from ground cloves was found to be 21. 4%. Such a low percentage was probably obtained due to some of the clove oil not being extracted from the DCM/clove oil mixture that was left to sit for one week, but a low percentage was also probable because the mass of the ground cloves would be greater since clove oil is not the only constituent in ground cloves.
In this lab, percent recovery was sacrificed in order to achieve a good purity. Conclusion After obtaining clove oil through steam distillation, the IR was successful in identifying the major constituent as eugenol. Although a low percent recovery was obtained the sample of clove oil was pure, which further proves that the major constituent can be identified as eugenol.