Extraction of Caffeine from Tealeaves

Extraction of caffeine from tealeaves

Abstract

This experiment focuses the use of multiple extraction technique to isolate, purify and characterize the alkaloid caffeine from tealeaves (Thea sinensis). Alkaloids are those occurring chemical compounds that have nitrogen base atoms and thoroughly have mild stimulating effect to the central nervous system of humans. Alkaloid caffeine has undergone boiling of 10 g of each tealeaves in 100mL distilled water and was extracted three times with dichloromethane (CH2Cl2). The residue which is the crude caffeine was collected after which the decantation of organic mixture extract and anhydrous sodium sulfate allowing it to evaporate until the solution reached the maximum state of dryness. The percentage yield was constantly computed by getting the ratio of the weight of the pure caffeine and the weight of the tealeaves used.

Introduction

The process of extraction or multiple extraction focuses on a mixture of organic compounds that is first dissolved in organic solvent (Klein, 2012). The theory of extraction lies in the concept of immiscibility between two phases to separate a solute from the other phase (Dizon et al., 2009, para.2). From this experiment, there are two kinds of extractions used. For solid-liquid extraction, there is a possibility that a water bath process for boiling is used. An example would be the water-tealeaves system which is the said experiment. Moving on, there is the counterpart which is the liquid- liquid extraction which makes use of a separatory funnel. For instance, a solution of aqueous acid is then added to the mixture, and the contents are shaken vigorously (Klein, 2012). After shaking, the organic and aqueous layer will thoroughly separate from one another (e.g. dichloromethane is the lower layer while the tea extract is in the upper layer). One layer would comprise the residue and that of the other which is the filtrate. In some experiments, the filtrate is often discarded.

The most important organic compound in this experiment is the extraction of caffeine. Caffeine is the only drug that is widely used and consumed in most foods. It has mild stimulating effect that can be quite "addictive" to some people, but it has a strong effect to those persons who abruptly stopped drinking any liquid-containing caffeine. A person may experience symptoms such irritability, headache, sleepiness and lethargy because of too much caffeine intake.

Figure 1. Structure of caffeine

Furthermore, the process of recrystallization is a primary method for purifying solid organic compounds. Crude organic compounds have impurities, meaning these compounds may either have soluble, insoluble or colored reaction mixtures. To obtain a pure compound, impurities must be removed. To establish fine recrystallization, it is important to note the solubility of organic compounds. Solubility states that "like dissolves like", meaning "compounds having similar features will be soluble in one another" (Brown, et al., 2003). The solubility of a solid in a liquid is the maximum amount of the solid that will dissolve in a given amount of a particular solvent at a given temperature (Bettelheim, et al. 2007).

The goal of the experiment can be done by isolating, characterizing and purifying the caffeine from tealeaves. After which the primary goal has taken place, the group is assigned to get the percentage yield for pure caffeine.

Results and discussion

The data below was gathered by the group efficiently. The 100mL beaker as well as the filter paper was pre-weighed or tare weighed. It would be easier to get the percentage yield if all the necessary apparatus was pre-weighed first. Moreover, Formula 1 clearly shows the exact amount of tealeaves (Lipton Yellow Tea Label) that the group used. They deducted the weight of 100mL beaker with tealeaves from the weight of the beaker alone. Same procedure was done for extracting pure caffeine (see formula 2).

Weight of beaker 100mL 49.6817g

Weight of beaker 100mL with tealeaves 56.2900g

Lipton Yellow Tea Label (weight of tealeaves) 6.6083g

Weight pure caffeine in filter paper 0.6237g

Weight of filter paper 0.6095g

Weight of pure caffeine 0.0142g

Volume of dichloromethane (CH2Cl2) 20mL *3 60mL

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