To carry out the experiment we need to get caffeine into a solution. We used a solid-liquid extraction by adding 14 tea bags into a 1L beaker with 6g of sodium carbonate, 250 mL of tap water and bringing this to a boil for five minutes on a hot plate. Sodium carbonate is a weak bronsted base, that neutralizes tannic acids extracted from tea, that interfere with the later sublimation operation.(1)
We turned the heat off after five minutes, added ice cubes to cool the mixture to room temperature, and carefully removed and properly discarded the tea bags. We then removed the cool beaker from the hot plate.
In order to obtain an organic solvent from the caffeine solution, a liquid-liquid extraction was used. We took a 1L separatory funnel in …show more content…
The only solid in the residue that undergoes sublimation is caffeine.(1) In order to determine if our procedure worked and caffeine was isolated we used thin layer chromatography (TLC) to compare the extracted material to a standard solution of pure caffeine. We dissolved the sublimed caffeine in 3 mL of methylene chloride in a clean vial and then swirl the residue in the flask with 3 mL of methylene chloride. A pure caffeine solution sample was obtained. On a chromatographic plate, two lines were drawn 0.5 cm away from the short ends. Then place one drop of the caffeine solution on the line and next to it one drop of the pure caffeine sample on the line. The chromatographic plate was placed into a jar, or a developing chamber, that contained 3 mL of ethyl acetate. Once the ethyl acetate reached the top line, the plate was carefully removed from jar, and the jar was capped. The plate was placed under a UV lamp, in order to see the location of the chemicals and they were circled in pencil, shown in Figure 1. The solutions are visible under UV light due to the flour, which is contained within the TLC plate. This procedure is a fast way to compare the purity of a sample through the retention factor (Rf ) values, which is the distance the caffeine and other organic compounds have traveled divided by the
We turned the heat off after five minutes, added ice cubes to cool the mixture to room temperature, and carefully removed and properly discarded the tea bags. We then removed the cool beaker from the hot plate.
In order to obtain an organic solvent from the caffeine solution, a liquid-liquid extraction was used. We took a 1L separatory funnel in …show more content…
The only solid in the residue that undergoes sublimation is caffeine.(1) In order to determine if our procedure worked and caffeine was isolated we used thin layer chromatography (TLC) to compare the extracted material to a standard solution of pure caffeine. We dissolved the sublimed caffeine in 3 mL of methylene chloride in a clean vial and then swirl the residue in the flask with 3 mL of methylene chloride. A pure caffeine solution sample was obtained. On a chromatographic plate, two lines were drawn 0.5 cm away from the short ends. Then place one drop of the caffeine solution on the line and next to it one drop of the pure caffeine sample on the line. The chromatographic plate was placed into a jar, or a developing chamber, that contained 3 mL of ethyl acetate. Once the ethyl acetate reached the top line, the plate was carefully removed from jar, and the jar was capped. The plate was placed under a UV lamp, in order to see the location of the chemicals and they were circled in pencil, shown in Figure 1. The solutions are visible under UV light due to the flour, which is contained within the TLC plate. This procedure is a fast way to compare the purity of a sample through the retention factor (Rf ) values, which is the distance the caffeine and other organic compounds have traveled divided by the