johnny DOe
CHM 235LL – Monday, 9/16/13
Extraction of Caffeine from Tea with Methylene Chloride
Abstract
Caffeine is natural chemical stimulant isolated from tea leaves. In experiment 13 we extract caffeine along with other organic chemicals such as tannins, cellulose, and chlorophyll. In the extraction of caffeine experiment the use of centrifuge and sublimation were vital. Of the entire tea bag 0.0176 g of caffeine was obtained, that makes 0.7292% of product (caffeine) from the tea bag. The product had a melting point of 222.6 – 230.0 C which showed impurities in the final caffeine product.
Introduction
Caffeine is an organic chemical compound that is found in tea and coffee plants and effects the central nervous system. It is a widely used stimulant in the United States. Caffeine’s medical properties are used as a diuretic, myocardial, bronchodilator, and can dilate various blood vessels in the human body.
Procedure
See prelab notes. We used magnesium sulfate instead of sodium sulfate. Which gave us a faster reaction time.
Results and Discussion
Table 1 – Caffeine Extraction Data
Description Value
Mass of leaves (g) 2.4134
Mass of caffeine (g) 0.0176
% recovery 0.7172%
Melting point 0 C - 225.6 – 233.4 Table 1 – Caffeine Extraction Data
Description
Value
Mass of leaves (g)
2.4134
Mass of caffeine (g)
0.0176
% recovery
0.7292%
MP 0C
225.6 – 233.4
Discussion
We had a percent recovery of 0.7292% of caffeine from the tea bag and a 32.0% yield recovery from the recommended 55mg of caffeine per tea bag. During the experiment, there were a few mistakes made that could have increased our overall percent yield. The most obvious is precision and careful movement when transitioning from one procedure to another. A few moments after we added 3ml of methyl chloride our vial began to build a lot of pressure, while we shook the solution, the cap popped off, spilling a portion of our solution. This caused us to lose a portion of the caffeine in the solution. If we would have centrifuge the mixture more times and at a faster speed when the methyl chloride was added, we would have receive a larger emulsion layer. When the mixture is centrifuged, it removes the middle emulsion layer and allows more of the methyl chloride, which contains the caffeine, to be successfully extracted. Another way we could have increased yield is to produce complete evaporation of the methyl chloride from the caffeine. If an insufficient amount of drying agent is used, then water will still remain in the solution. This would cause evaporation of the methyl chloride to take longer and losing caffeine in the process.
The product’s melting point, which was 225.6 – 233.40C which was a fair margin from caffeine’s text book melting point of 2360C. This melting point shows impurities in the final product. These impurities are due to the leaves other compounds like tannins, cellulose and chlorophyll. The caffeine could have been more pure if the solution was centrifuged for a longer rate of time and at a faster speed. Also when transferring the emulsion to the earl meyer, flask traces of the waste product or drying agent (methyl chloride) could have been left behind.
Calculations
How many cups of coffee to kill my teacher? (145lbs)
LD50 Caffeine 192mg/kg
Springer = 145lb/2.2 = 65.9kg x 192mg/kg / 55mg caffeine/1 cup of coffee =
230 cups of coffee to kill a person of 145lbs
Percent recovery
1. m (caff)/m (tea) x 100 =
.0176 / 2.4134 x 100 = .7292% was recovered from the whole tea bag
2. m (caff)/ 55mg x 100 =
.0176 g / 55mg x 100 = 32.0% Lipton tea states that there are 55mg of caffeine per tea bag, we were only about to recover 32.0% of that caffeine
Conclusion
A yield of 0.0176g of product (caffeine) was extracted from the tea bag, with melting point of 225.6 – 233.40C. The total percent yield was 0.7292% of the tea bag and a percent yield from the recommend caffeine from a tea bag was 32.0%. The melting point test
