Extraction of Caffeine

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Extraction of Caffeine from Tea leaves

Casinabe, Antonio Karlo,*Catahay, Jesus Alfonso, Cerdena, O’neil, Cordova, Robelle Department of Biological Sciences, College of Science
University of Santo Tomas, España Street, Manila 108
Group 4 2MB

Date Submitted: December 13, 2012
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ABSTRACT:

The purpose of this experiment is to extract the amount of caffeine present in tea bags. In this experiment, isolation, characterization and purification of caffeine from tea bags was done through the use of Solvent Extraction and Partitioning method. First, the tea bags were weighed and boiled for five minutes. They were allowed to cool and then they were mixed with dichloromethane. The experimenters performed a technique called single extraction. After the two distinct layers were clearly visible in the separatory funnel, the organic layer or the DCM containing the extracted caffeine in the water was extracted. The process was repeated three times and the collected organic layer (DCM layer) was placed in an Erlenmeyer flask. The combined organic layer was transferred back to the separatory funnel and was washed with sodium hydroxide. After washing, the organic layer was again extracted from the funnel and placed in a beaker containing anhydrous sulphate. The solution was allowed to evaporate to produce crystals of caffeine. The crystals of caffeine produced were combined with ethanol and were placed in a hot water bath until the mixture is clear. The solution was filtered and dried, then weighed. The amount of the pure caffeine was recorded and the percentage yield was computed. Melting point was determined for the characterization of the crystalline caffeine. -------------------------------------------------

INTRODUCTION

Caffeine extraction is a common technique used in chemical laboratories. It is done to show levels of caffeine present in drinks and foods before releasing them in the market. Since caffeine is the most common stimulant used and abused by human beings, knowledge of its concentration and content through its extraction will be very useful to avoid addiction.

Caffeine (C8H10N4O2 ) is a naturally occurring alkaloid and belongs to the family of xanthines, appears as white crystals on room temperature and acts as a stimulant drug. It stimulates the central nervous system, removes drowsiness and re-establishes mental alertness. It is commonly consumed by human beings in forms extracted from coffee beans and tea bush’s leaves, and also from different commercial products like foods and drinks containing products derived from the kola nuts.

Figure 1. Chemical structure of Caffeine
Figure 1. Chemical structure of Caffeine

Extraction is the process of removing a particular compound of interest from a mixture of compounds. The experiment used a type of extraction called Solvent Extraction and Partitioning in order to extract caffeine. Solvent extraction and portioning is a technique where a solvent is used or added to remove or extract a compound from a mixture. In this experiment, the initial solvent used for extracting caffeine is water. Then, multiple extractions were also used. These extractions were done in a repeated extraction, and were seen addition and mixing of dichloromethane in/from the separatory funnel to extract the majority of the caffeine.

A melting point is the temperature at which a material melts at atmospheric pressure. Their determination has many uses in chemistry such as for characterization, purity or molecular structure determination. It is usually expressed as a range between first appearance of liquid within the sample to the disappearance of the last traces of solid. Pure compounds characteristically have a sharp melting range while most mixed or impure compounds have a broad melting range due to the presence of impurities in the compound. In the experiment, melting point was determined for characterization...
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