Isolation Of Caffeine

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Isolation of caffeine


Abstract: The objective of this experiment is to isolate caffeine from tea leaves or coffee and then purify using sublimation as well as determine the purity by melting point.
It was concluded that 18.7mg of caffeine were found in a single Louisiana Tea sample. The purified caffeine sample was found to have a melting point of 505K compared to the textbook caffeine melting point of 509K.







Backround:
Sublimination is when a substance in the solid phase passes directly into the vapor phase without going into the liquid phase. This happens because the vapor pressure of a substance generally goes up as temperature increases and the boiling point of a liquid happens when its vapor pressure is equal to the applied pressure. If this vapor can then be re-solidified it will separate compounds with low vapor pressures and high vapor pressures. This re-solidification is usually collected in crystal form on the outside of a glass tube with some sort of very cold liquid inside to attract and solidify the compound with a higher vapor pressure in a vacuumed atmosphere. This method is generally quick however it is not as selective as other methods of purification.



Objective and Materials:
The objective of this experiment is to isolate caffeine from tea leaves or coffee and then purify using sublimation as well as determine the purity by melting point.


Materials used are as follows: sublimination tube, test tubes, tea, coffee, methylene chloride, potassium carbonate, centrifuge tube, vacuum hose, Pasteur pipet, available water, 200mL beaker, hot plate, sand bath, micropipette bulb, all materials were provided by the University of Arizona Chemistry Department.




Procedure:
The procedure for this experiment is listed on page 43(Organic Chemistry laboratory Manual, Haden/McNeil, 2003-04)




Data:
All data is in laboratory notebook.







Calculations:

The following i...