The Extraction of Caffeine from Coffee Abstract

Name: Aliyana Campbell Date: June 10th, 2024 CHM-251: Organic Chemistry I The Extraction of Caffeine from Coffee Abstract Caffeine is the most widely consumed psychoactive drug in the world. It is also one of the only few that is legal in many parts of the world. Caffeine is a stimulant, meaning it affects the autonomic (involuntary) nervous system of the human body. It works by boosting the metabolism of the brain and blocks the brain from receiving hormones that induce drowsiness. Caffeine is present in many naturally occurring substances, such as tea, coffee, and chocolate. The purpose of this experiment is to extract caffeine from black coffee. Background Many constituents of coffee and tea, including caffeine, are soluble in water. But with caffeine being only partially polar, it can dissolve in both polar and nonpolar solvents. In order to separate caffeine from the polar solvent that is water, the caffeine must be dissolved in a nonpolar solvent, such as chloroform. The other constituents of the coffee are much more polar than caffeine and will not dissolve as well in chloroform. This way, the caffeine can react with the chloroform and can later be separated from it. Materials & Methods Materials: – – – – – – – Separatory funnel Ring stand Black coffee Chloroform 250 mL Erlenmeyer flask 100 mL graduated cylinder 150 mL beaker Methods: A separatory funnel and a corresponding ring stand were obtained. The stopcock at the bottom of the funnel was checked to make sure it did not malfunction (i.e., it was not leaky). Upon making sure the stopcock at the bottom of the separatory funnel was closed beforehand, the funnel was set in the ring stand and 75 mL of black coffee was poured into it. Then, 20 mL of chloroform was obtained in a graduated cylinder and then added to the coffee in the funnel. After being closed up with its stopper at the top, the separatory funnel was then gently removed from the ring stand and slowly inverted and reverted for 1-2 minutes. Every other inversion, the stopcock was slightly opened to release any built-up gas. The funnel was then returned to the ring stand for a few minutes to allow the two layers of liquid to separate. The chloroform was the lower layer, with the coffee on top, and there was an emulsion between the two layers (an emulsion is a region where “bubbles” of one liquid are suspended in the other liquid, and the two refuse to separate). Once the two layers had separated, the layer of chloroform (including the emulsion layer) was drained into a dry 250 mL Erlenmeyer flask and set aside. A fresh 20 mL portion of chloroform was added to the coffee remaining in the separatory funnel, and the funnel was inverted and reverted for 1-2 more minutes. The two layers were allowed to separate again., then the lower chloroform layer was drained into the 250 mL flask already containing the first portion of chloroform. At this point the two portions of chloroform chloride are together in the flask. An approximate amount of 2 grams of anhydrous sodium sulfate was weighed out and added to the chloroform in the flask (this was done to absorb any water that was left in the chloroform). The flask was swirled and then left to sit for about 12 minutes. During this time, a 100 mL beaker was weighed and its mass was recorded. Afterward, the chloroform was decanted into the beaker, leaving all the sodium sulfate behind. The beaker of chloroform was then transferred to a warm-water bath under a chemical hood and left there to evaporate. Once all the chloroform had evaporated, the beaker was removed from the bath re-weighed to determine the percent recovery of caffeine. Results The weight of the clean empty beaker was 45.31 grams. After the water bath when the liquid chloroform had completely evaporated, the beaker weighed 45.42 grams. This means that 0.11 grams of caffeine remained in the beaker. Percent recovery was calculated using this formula: 𝑐𝑎𝑓𝑓𝑒𝑖𝑛𝑒 𝑤𝑒𝑖𝑔ℎ𝑡 (𝑔) 𝑏𝑒𝑔𝑖𝑛𝑛𝑖𝑛𝑔 𝑐𝑜𝑓𝑓𝑒𝑒 𝑤𝑒𝑖𝑔ℎ𝑡 (𝑔) * 100 = percent (%) recovery With the 75 grams (converted from mL) of coffee at the beginning of the experiment and the 0.11 grams of caffeine remaining at the end, the percent recovery of caffeine was determined to be 0.15%. Discussion This experiment was considered successful since it produced the expected end result. There may have been a way to get a greater percent recovery of caffeine. There was an option in the experimental process to separate the filtered chloroform from visible water droplets by decanting the chloroform into a new flask. However, this step was skipped because there were no visible water droplets present. When the first layer of chloroform was drained during the first few steps of this experiment, the emulsion of bubbles was not included. Perhaps if the emulsion had been drained into the flask along with the rest of the chloroform, there would have been a higher percent recovery of caffeine. References Rodak, K., Kokot, I., & Kratz, E. M. (2021, September 2). Caffeine as a factor influencing the functioning of the human body-friend or Foe?. MDPI. https://doi.org/10.3390%2Fnu13093088