Question

What are the chemical reactions (with structures) for the sequential separations of caffeine from tea? First Tea (caffeinated) with dichloromethane, then that organic solution with NaOH, then that organic solution with water ? Trying to isolate caffeine, eventually using a drying agent after the water step. A flow chart will also work to show the reactions and products!

Answer 1

Tea mainly contains water insoluble material such as cellulose. Which is discarded in first step. Then by adding Dichloromethane (DCM) we solubalize tannins and caffeine from the tea solution. By extracting with NaOH solution we make tannins salt water soluble and thus DCM layer remains with only caffeine. This DCM layer is washed with water to remove any inorganic impurity and then DCM layer is dried over anhydrous Na2SO4. After evaporating DCM we get pure caffeine. Further to purify it, we can use sublimation process.