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Example Technique Lab Report Rev 7-2008

Example Technique Lab Report Rev 7-2008 - Isolation of...

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Isolation of Eugenol from Cloves by Steam Distillation and its Identification by Infrared Spectroscopy Eim A. Chemist CHEM 303 June 16, 2005 INTRODUCTION “Essential oils” are the volatile components associated with the aromas of many plants. 1 In this experiment, the essential oil eugenol (the main component of oil of cloves) will be isolated from ground cloves using the technique of steam distillation, which is often used to isolate liquid natural products from plants. 2 The principle of steam distillation is based on the fact that two immiscible liquids will boil at a lower temperature than the boiling points of either pure component, because the total vapor pressure of the heterogeneous mixture is simply the sum of the vapor pressures of the individual components (i. e. P T = P o A + P o B , where P o is the vapor pressure of the pure liquids). This leads to a higher vapor pressure for the mixture than would be predicted for a solution using Raoult’s Law (that is P T = P o A N A + P o B N B , where N is the mole fraction of the component in the mixture). The higher total vapor pressure leads to a lower boiling point for the mixture than for either single component. 2 During the isolation of a liquid natural product by steam distillation, water is one of the components, and the liquid natural product being isolated (which is immiscible with water) is the other component. The product can be steam distilled from the natural source at a relatively low temperature (always less than 100 o C), thus avoiding decomposition of the product. 2 Steam distillation can be carried out in two ways: the direct method and the live steam method. 3 In the direct method, steam is generated by boiling a mixture of the source of the compound of interest and water. The live steam method is carried out by passing steam from an external source into the distillation flask. The direct method of steam distillation will be used in this experiment and is carried out on a semi- micro scale using the apparatus shown in Figure 1 below: Figure 1 4 Page 1
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Ground cloves and water will be charged into the distillation flask shown in the figure. The mixture
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