Why is caffeine extracted in base

An average 30g of tea can contain ll0 mg of caffeine thereby making tea a significant source of caffeine compared to other beverages.

Caffeine can stimulate nervous system and can cause relaxation of respiratory and cardiac muscles. Caffeine is well known to increase both the alertness level and attention span. But like all other addictives, tea also shows withdrawal symptoms like headache, nervousness and insomnia for a regular consuming person. Caffeine, 1,3,7 - trimethylxanthine, belongs to a wide class of compounds known as alkaloids. These are plant derived compounds with complex structure containing nitrogen, and usually have roles in physiological activity.

Extraction is a method used for the separation of organic compound from a mixture of compound. This technique selectively dissolves one or more compounds into an appropriate solvent. The solution of these dissolved compounds is referred to as the extract. The dichloromethane - caffeine mixture can then be separated on the basis of the different densities of dichloromethane and water because dichloromethane is much denser than water and insoluble in it.

Residual water is separated from dichloromethane by drain out the dichloromethane through separating funnel, thus dichloromethane passed through the funnel while polar solvents such as water is still remains in the funnel. Water and dichloromethane is slightly soluble in each other.

So, after separating the solvents, residual water will remain the organic layer. Mainly anhydrous sodium sulfite is used for the removal of water from organic layer. Be certain that there is no magnesium sulfate in the solution. Stripping this solution to dryness will take less than 5 minutes. You will be left with a small amount of residue with a greenish tinge. Obtain the weight of crude caffeine by difference. Add mL of hot acetone to dissolve the crude caffeine and transfer the solution to a 50 mL Erlenmeyer flask for recrystallization.

Add a few drops of petroleum ether until you reach the cloud point caffeine is less soluble in this mixed solvent and is just beginning to precipitate and then cool the solution.

If you do not get a precipitate, you may have used too much acetone, carefully boil off the excess on a steam bath using a boiling stick for ebullation. A second crop of caffeine may form in the filtrate as the solvent evaporates. This second crop can also be collected by vacuum filtration but keep it separate from the first crop.

The sublimation will be performed as described by your instructor. You will use 50 mg of your caffeine to make a salicylate derivative and sublime the remainder which should be at least 50 mg.

You will not take a mp of the purified caffeine which would require a sealed capillary to prevent sublimation near the melting point. Save the purified caffeine in a sealed vial. You will use some of this material for TLC analysis next week. Caffeine is a base which can react with acids to form salts. A well characterized salt of caffeine is caffeine salicylate formed by using salicylic acid. This derivative of caffeine has an accurate melting point.

Later this semester, you will be required to make solid derivatives of other compounds. Using an analytical balance there are several top loader balances in the lab across the hall which will quickly weigh to 0. Add 1 mL dropwise of petroleum ether and allow the mixture to cool and crystallize. If necessary, cool in an ice-water bath.

University of Missouri—St. Louis ; Chemistry. Procedure Place 15 g of tea leaves, 5 g of calcium carbonate powder and mL of water into a mL beaker.