Question

I did the Isolation of Caffeine from Tea Leaves experiement. starting marterial was 5g of tea leaves, 2 g of calcium carbonate powder and 50 mL of water were mixed well in 100-mL round bottom flask with condenser reflux. The filtrate was extracted with 10- mL portion of methylene chloride, and dry the product with anhydrous magnesium sulfate

1.can you please write what is the chemical reaction carried out in this experiment in detail please. any chemical equation? thanks!!

Answer 1

This is an extraction process and there is no reaction involved with Caffeine itself but during the extraction, there is one chemical process takes place.

The extracts contain caffeine as well as tannins which are phenol derivatives and soluble in both water and in dichloromethane. To remove this tannins, CaCO3 is used which would convert these phenols to its Ca-salt and would no longer be soluble in dichloromethane, so will remain in the aqueous layer.

The general reaction is -

ArOH + CaCO3 ---> (ArO-)2Ca + H2O