Abstract
Caffeine is an alkaloid stimulant with a cyclic backbone structure analogous to the purine structures of DNA. Caffeine is found in numerous applications and can stimulate different parts of the body, possibly causing addiction, insomnia, and headaches. Using the proper extraction methods, the caffeine within a tea bag could potentially be isolated to yield a pure solid; the mass of this solid would reflect the actual yield of caffeine in the tea.

Introduction
Caffeine belongs to a large class of organic compounds called alkaloids, which vary widely in structure and reactivity. These nitrogen based compounds are found in plants and often taste bitter 2. Alkaloids can be found in different forms such as nicotine, morphine, or cocaine. The structure of caffeine is shown below along with the purine ring.

Figure 1: Structure of purine and caffeine

Caffeine is found in a number of foods and beverages. Such has chocolate, soda, and over the counter medication. The purpose of this experiment was to isolate caffeine that is found in tea by using the techniques of extracting, separating, drying, and sublimation. To do so, caffeine must be introduced to a solvent that is both volatile and insoluble to water; a perfect example is dichloromethane. Caffeine has a greater affinity for dichloromethane and will easily dissolve in this solvent over water; however, caffeine is not the only organic substance found in tea that is capable of reacting with dichloromethane. Along with caffeine, tea contains another substance, tannins, which are capable of dissolving in water as well 2. This is due to dipole-dipole interactions that result from the greater polarity of caffeine and hydrogen bonds between caffeine and water. To prevent the tannins from being mixed in with the caffeine, a common salt can be introduced to solution to revert back tannins to phenolic anions which is not soluble in dichloromethane.

Figure 2: With addition of sodium carbonate, tannins can be reverted to a solid state.

In dichloromethane, caffeine will have a greater attraction for the organic solvent and the hydrogen bonds between caffeine and water will be broken. Using the separatory funnel, two insoluble solutions can be separated, isolating caffeine and the new phenol anion from one another. The denser dichloromethane layer can then be released from the funnel to render a pure solution of caffeine and dichloromethane. To ensure that no water interferes with the interaction of caffeine and dichloromethane, anhydrous sodium sulfate could be used to absorb any excess water that may have escaped from the tea solution. If heated, the solvent would quickly evaporate due to low boiling point of dichloromethane. The remaining sold would then be pure caffeine.

Results
Table 1: Initial and final values determined throughout extraction | Weight (g) | Weight of tea bags | 1.9941 | Weight of anhyrous sodium*prior to separating | 2.027 | Weight of anhyrous sodium*post separating | 0.5245 | Weight of Caffeine | 0 | Percent Yield | 0 |

The predetermined mass of two combined bags of chamomile tea was 1.9941 g. To extract the caffeine, the heated tea solution along with 5mL of dichloromethane, was poured into a separatory funnel and inverted for mixing. The stopcock had to be released after each inversion to release gas. Upon settling, the solution separated into 2 distinct layers: dichloromethane and the tea solution. The density of dichloromethane is 1.32 g/mL while the density of water is close to 1 g/mL causing the dichloromethane to sit at the bottom 1. After draining, the process was repeated again. The remaining tea solution was heated and rendered a final mass of 0 g. Considering chamomile was used, a 0% yield was to be expected.

Discussion
As is expected, the percent yield of caffeine was definitely not 100%. If this experiment were to be done with caffeinated tea, then perhaps some experimental changes could be introduced in a repeated experiment. During the conversion of tannins back to salts, anionic surfactants are produced. These surfactants were responsible for the emulsion bubbles and may have restricted the amount of caffeine released from the funnel. Nevertheless, the purpose of adding sodium carbonate was to alter the chemical structure of tannins. Converting it back to a salt that is insoluble in dichloromethane was imperative to the extraction of caffeine. Even though a decaffeinated tea was used, the process by which the nonexistent caffeine was extracted may have yielded strong results for caffeinated tea.