Organic Chemistry Lab

Being able to extract a compound or substance from a product or object will encourage us in being able to do the same in a similar manner with a tea solution. Extracting compounds is an important step in any kind of organic chemistry lab and will help us be better at accomplishing the experiment in a much faster and accurate rate than from before.

Experimental To begin the experiment, a tea solution must be made by incorporating a tea bag into a beaker filled with almost boiling water and the weight of the tea bag should be given from the instructor, just for result comparison purposes. Place 20 mL of water in a 50-mL beaker and proceed to heat until a near boiling state has been reached, while some cover is on top of the beaker. Put any
kind of tea bag that supplies caffeine into the boiling water and make sure it lies flat on the bottom of the beaker. Continue covering and heating the beaker at a steady, easy heat for around 15 minutes. Once the time has come, try to extract as much liquid from the soaked tea bag as possible, without trying breaking the tea bag and releasing all the other components we do not need. Once a sufficient amount of tea has been made and extracted, add 1.0 g of sodium carbonate to assist in converting the acidic compounds that we do need, into a liquid/water state. A Buchner filter setup must be made, according to the diagram below:

Once this setup has been made and the vacuum suction is sturdy and strong enough to filter, insert the tea solution onto the moistened filter paper at small amounts, to ensure in obtaining the most amount of caffeine that is possible in getting. After one filtration has been done, a second run in filtering was also done, to make sure the filtered tea solution was believed to be fully filtered from all the impurities that remain in the tea solution. Clean up the buchner funnel setup and begin to create an SPE column, as shown in the diagram below:

A similar setup to the Buchner filtering setup should be used, but instead of the stopper for the Buchner funnel, a stopper with a narrower hole for the SPE column should be used at the appropriate place.
Conditioning would be the first step by passing 5 mL of distilled water and 5 mL of dichloromethane through the column and making the column much more easier to work with and allows for faster and better extractions when adding the tea solution. Load is the next step by beginning to add the caffeinated tea solution and slowly vacuuming, where the column will start to change to a brownish color and slow down the extraction just by a bit. Once the caffeinated tea solution has been extracted and the caffeine and other impurities remain in the brownish-colored column, Washing is the next step by adding another 5 mL of water and 5 mL of dichloromethane through the column, to get rid of the impurities lodged along with the caffeine. The column now only contains the desired compound caffeine and to extract caffeine from the column, a smaller one-armed Erlenmeyer flask that is clean will used to hold this extraction and 5 mL of ethyl acetate will be passed through SPE column, to obtain and remove the caffeine from the SPE column. A small one-armed Erlenmeyer flask containing 5 mL of ethyl acetate along with the compound caffeine, should be the result after using the SPE column
correctly Proceed to add 0.5 g of sodium sulfate, which will be used as a drying agent in removing as much ethyl acetate, not containing the caffeine, as sodium sulfate can.
Be sure to record the weight of a 50-mL beaker that will be used in the step, in order to determine the weight of the crude caffeine. Transfer the ethyl acetate liquid into another 50-mL beaker, rinse the small one-armed Erlenmeyer flask with another 5 mL of ethyl acetate, and transfer the remaining ethyl acetate liquid into the beaker once more, to ensure all the caffeine has been gathered and transferred to the beaker. To remove the ethyl acetate solution, a blowing procedure will be done by attaching one end of the tube to an air valve and the other to a small glass pipette. A hot plate would also assist in the evaporation of ethyl acetate, but only at a low and substantial heat. Slowly glaze the top of the beaker with the glass pipette, where the blown air is pushing the ethyl acetate solution into one side of the beaker and remain position like this until all of the ethyl acetate liquid is no longer visible. Weigh the 50-mL beaker containing only a brown residue on the bottom, indicating a resulting amount of caffeine, and subtract the recorded weight of the 50-mL beaker and caffeine with the weight of the clean 50-mL beaker that was recorded before adding the ethyl acetate solution with caffeine. Put any extra dichloromethane in the halogenated waste bottle and if a sufficient amount of caffeine was
obtained, melting points and an IR spectrum can also be done.

The % recovery of the crude and purified caffeine can be found when inserting the appropriate values into the following formula:

% recovery = [(g of pure caffeine) / (g of crude caffeine)] x 100% [Figure 3]

When finishing our experiment and after undergoing filtering, extracting, and blowing, -0.01 g of crude caffeine was gathered and weighed, along with the beaker the compound was lying on. An inefficient amount of crude caffeine was obtained, thus prevents us from undergoing the purification process and not obtaining an amount of pure caffeine or a % recovery between the crude and pure caffeine. Along with the purified caffeine’s melting point, since no purified caffeine was able to be obtained due to our insufficient amount of crude caffeine gathered, no heating procedure was done and thus, no melting point was able to be recorded for the pure caffeine. The same explanation for the comparison between the experimental and literature value of the pure caffeine’s melting point, no experimental value of the pure caffeine’s melting point was able to be obtained and thus, prevents us from comparing the two values with each other, in order to see if a flaw or some error was associated while heating up a purified compound of caffeine. The possible errors that was associated in obtaining a negative or nonexistent amount of crude caffeine could have been made in the tea making procedure. When attempting to extract the last remaining amount of tea that could have been soaked up by the tea bag, the little impure particles will also be transported along with the tea and will create a larger headache than the experiment is supposed to give. An improper extraction of the tea from the tea bag could have been the main error associated in obtaining almost no crude caffeine, when completing the experiment. Filtering the tea solution is another part of the experiment, where sources of error could have been found and made like the amount of time put into each filtering and carefully filtering out the liquid tea from the impurities that lies inside. Another source of error when filtering the tea solution could be the amount of tea solution added to each step of filtration, but my partner and I made sure to use small amounts for each filtration step to extract the most amount of tea holding the caffeine compound. The last part of the procedure where sources of error could have been made is the SPE column procedure and a major error that may or may not have occurred was the incorrect amount of water, dichloromethane, and ethyl acetate added into the column to extract their appropriate component. Since we only used 5 mL of each solution just to play it safe and any serious error, no variation or difference in the amounts was used and an amount ratio of 1:1:1 for the solutions being added could have been the main faulty we decided to do. Considering that the amounts of water, dichloromethane, and ethyl acetate were not given to us in the procedure, adjusting the amounts and testing out the volumes at small amounts could have given us much more crude caffeine during the SPE column procedure and a higher weight that was done at the end of the experiment.