lab report

Isolation of Caffeine from Tea
Objective:
The method extraction is widely used in molecule isolation process as it is very effective in target molecule separation when compared to other conventional techniques. In general, extraction is performed by adding third chemical namely solvent to isolate desired chemical compound/ molecule. In this experiment our target is to isolate caffeine from tea, since caffeine is widely used drugs in US for its alkaloid properties which are widely present in coffee, tea, cola, chocolate and many non-prescribed drugs.
The molecule caffeine is having high solubility in water due to its more polar and base sites in its molecular structure, in addition this property also makes caffeine non-polar in nature just by adding aqueous base which reduces solubility in water but increases in organic solvents (less polar). For this experiment we will be using methylene chloride for caffeine extraction using separatory funnel, as methylene chloride also extracts neutral molecules but in tea very minimal amount present hence molecules other than caffeine will not be of major concern for impurity as acidic compounds like tannic acid stays in aqueous phase as deprotonated molecule.
Once the organic phase is separated will be proceeded to evaporate for crude caffeine product which are further sublimed under partial vacuum condition to achieve vapor state to remove volatile impurities where caffeine will be re-condensed as white substance in known pure form of caffeine.
Isolation of Caffeine from Tea:
The schematic representation of sublimation experimental step in below image,
Procedure:
1. The400 mL beaker was taken and 5 tea bags are placed in it and filled with 150 ml of de-ionized water and bring to boil using hot plate allowed to boil continuously for 15 minutes, additional water will be added if level comes below 150 mL during boiling process.
2. Carefully remove the beaker from the hot plate, remove and discard the teabags, and dissolve 15 g of Na2CO3 in the tea solution by stirring.
3. Cool the tea solution in an ice-water bath (to 25o – 30o C), then transfer it into a separatory funnel, using a funnel.
4. Add 20ml of methylene chloride, again via a funnel, and shake the mixture gently unless will form emulsion on vigorous shaking. If this happens, let it stand for about 15 minutes to allow layer separation.
5. Water drop technique is used for layer confirmation as in this bottom layer is colourless methylene chloride and top layer an...