Extraction of caffeine from tea in experimental classes of organic chemistry: comparative study

Caffeine is a stimulant derived from xanthine. Its extraction is a common procedure discussed on laboratory lessons for chemistry undergraduate students, especially in laboratory disciplines of organic chemistry. Instant black tea is one of the most used raw materials in laboratory classes about caffeine extraction, because of its high solubility in water.1 This study aimed at optimizing the procedure of caffeine extraction from instant black tea, making it more time-saving for organic chemistry laboratory classes. Figure 2 shows the two methods used for the extraction of caffeine, after which, the product weight was obtained for calculating the yield. The caffeine was characterized by the murexide reaction (figure 1), placed in a heated porcelain capsule with 4 drops of H2O2 and 6 drops of HCl 6M. NH4OH 6M was added to the red residue that become violet. Table shows the extraction data. The Ext 06 presented the best yield, being indicated for a class of 100 minutes. For classes of 200 minutes you can reproduce Ext 04, which doesn’t use 10 g of catalyst. Using the suggested methods, it is possible to perform reflux and caffeine extraction in one class only. Thus, the time required for extraction with other methods can be used to perform other extractions and analyzes during the same class.