Extraction of Caffeine from Tea Leaves

Abstract This work describes the extraction of caffeine from tea leaves to determine its % caffeine. The extraction process selectively dissolves one or more compounds in a mixture into an appropriate solvent. In this experiment, it was visible in the process wherein the components of the tea leaves were dissolved in two solvents, water and dichloromethane (DCM), with DCM used for multiple extractions. The organic layer was evaporated and the determined % caffeine was 0.12%. Furthermore, the purified caffeine was subjected to sublimation process and melting point determination; the result was compared against the theoretical melting point of standard/pure caffeine (237°C). The process resulted in a melting point range of 225°C - 232 °C, which is less likely pure than the standard compound.

Introduction Caffeine is an alkaloid, a class of naturally occurring compounds containing nitrogen and having the properties of an organic amine base, purine. Caffeine, which is found in more than 60 plant species, belongs to a family of naturally occurring compounds known as xanthines [1]. The xanthines, which come from plants, are possibly the oldest known stimulants [3]. Caffeine is the most powerful xanthine in its ability to stimulate the heart, respiration, and the central nervous system. It is also a vasodilator (relaxes the blood vessels) as well as a diuretic (increases urination). Its use, however, can also cause nervousness, insomnia and headaches, and is physically addictive.

Caffeine is ingested by people in a number of things, from beverages like tea and coffee to medicines. Tea has been consumed as a beverage for almost 2,000 years, starting in China, thus, making it the most widely-consumed beverage around the world after water. It has a cooling, slightly bitter, astringent flavor which many enjoy. It is produced by steeping the young leaves and buds of the tea plant, Camellia sinensis, in freshly boiled water. Today, two principal varieties are used,