Experiment 7- Isolation of the Major Component of Clove Oil
1.) Briefly explain the concept of steam distillation. What is the difference between a simple distillation and a steam distillation? When a mixture of two immiscible liquids are distilled it is referred to as codistillation. This process is referred to as steam distillation when one of the liquids is water. This distillation is used to separate organic liquids from natural products and reaction mixtures in which the final product results in high boiling residues such as tars, inorganic salts, and other relatively involatile components. It is useful in isolating volatile oils from various parts of plants and not useful in the final purification of a liquid because it cannot separate components that have similar boiling points. The difference between simple distillation and steam distillation is that more water may be added during the distillation during steam distillation. Simple distillation allows a separation between two compounds of 60-70 degrees C or greater, or can be used when separating a liquid from non-volatile solids. Steam distillation is used to distill organic compounds that would decompose during simple distillation. 2.) The major component of clove oil is a compound call Eugenol. One of the minor components is called Acetyleugenol. Draw the structures of both of these compounds (Wikipedia may be helpful). What would be a good estimate for the pKa of Eugenol?
Eugenol, pKa=10.19 at 25 degrees C.
3.) The recovered clove oil will be analyzed by Infrared Spectroscopy. What are the basic principles of Infrared Spectroscopy (can be included in the introduction if you prefer). How will we be able to distinguish between Eugenol and Acetyleugenol by IR sprectroscopy? Molecule atoms act like they are connected by flexible springs instead of rigid bonds which resemble a ball and stick model. The components of the molecule can oscillate in different vibrational modes. As IR radiation is passed through a sample of pure compound the molecules absorb radiation from the energy and frequency needed to bring about transitions between vibrational ground and vibrational excited states. The IR spectrum then graphs the amount of IR radiation the compound absorbs in wavelengths. IR sprectometry is mostly used to detect the presence of specific functional groups and other structural features from positions and intensites. We can distinguish these compounds by using the C=O stretching which is obtained at 1700-1735cm-1 given by the acetyleugenol. Purpose:
The purpose of this experiment is to isolate and identify the major constituent of clove oil. This will be done using steam distillation and infrared spectrometry. Theory:
In this experiment my partner and I should be able to isolate an essential oil from ground cloves using steam distillation and extraction. After the distillation and extraction processes an infrared spectrometry sample will be taken to identify the isolated components. Having assembled two apparatus’ already for lab this semester this should not be a problem. We will use an apparatus indicated in our lab manual that is commonly used for steam distillation which is similar to the apparatus of simple distillation. Using five grams of ground cloves and fifty milliliters of water we will steam distillate the crushed cloves until we collect a few drops on a watch glass and they appear clear like water and are odorless. Our lab manual indicates that we may have to distill about 150ml of liquids before this happens. After we have obtained a sufficient of amount of clear fluid we will extract the solution twice with dicloromethane then twice again with sodium hydroxide. This solution obtained will be adcidified with 10ml of 3M hydrochloric acid. The acidified solution will be mixed one last time with dichloromethane and the final organic Eugenol solution will be...
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