Week 5 - Steam Distillation of Monoterpenes (S)-(+)-Carvone...

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Steam Distillation of Monoterpenes ( S )-(+)-Carvone and ( R )-(+)-Limonene from Caraway Seeds/Analysis of Products by Infrared Spectroscopy and TLC Mark Gumapas October 11, 2007 Methods and Background The purpose of this lab is to successfully isolate carvone, an essential oil, from caraway seeds by means of steam distillation. After getting the essential oil from the seeds, a thin layer chromatography and infrared spectroscopy will be performed to verify the results of our experiment. Carvone Enantiomers Carvone is most abundant in 2 enantiomers. It is found in ( S )-(+)-Carvone, which smells like caraway, and ( R )-(-)-Carvone, which smells like spearmint. For the purpose of this class, the enantiomers of carvone are known as terpenoids. These two specific enantiomers are monoterpenes. Enantiomers have identical physical properties (BP, FP, MP, etc…), an asymmetric carbon (chiral center), and are nonsuperimposable chiral images, but they have opposite optical rotation, and one enantiomer undergoes a chemical change at a rate different from its mirror image. As stated, the biggest difference between the two enantiomers is their smell. Due to their differences in stereochemistry, the receptors on the cells in our nose are chiral because we can distinguish the difference between the two. The main experiment of this lab is to successfully perform a steam distillation. The steam distillation is used as a mild method for separating and purifying a volatile liquid that is immiscible or insoluble in water. When this is the case, a codistillation of the water and volatile substance is necessary to separate them. Slightly different from previous labs where we would boil our solution, the caraway seeds will be placed with water and boiled together. The main difference between this distillation and simple and fractional distillations, is the setup of the apparatus. An additional piece is added to the stillpot to prevent the mixture of water and caraway from splashing into the condenser. Also in this lab, thin layer chromatography (TLC) was used to verify our results of our distillation. In organic chemistry, TLC is a quick way of analyzing the progress of a reaction. In TLC, unlike column, the mobile phase is not flowed over the compound and stationary phase, but instead placed below the stationary phase and allowed to rise via capillary action. In TLC, the stationary phase is a thin layer of absorbent material, and a small amount of the solution to be separated is put on the absorbent. When the
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This lab report was uploaded on 04/07/2008 for the course CHEM 233 taught by Professor Landrie during the Spring '08 term at Ill. Chicago.

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Week 5 - Steam Distillation of Monoterpenes (S)-(+)-Carvone...

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