Write equations showing how caffeine could be extracted from an organic solvent and subsequently isolated
http://www.seriaz.org/downloads/4-caffiene.pdf
To extract caffeine from an organic solvent and subsequently isolate it, we can use the following equations:
1. Extraction:
Caffeine (in organic solvent) + Aqueous solution → Caffeine (in aqueous solution) + Organic solvent
During extraction, caffeine is transferred from the organic solvent phase to the aqueous solution. The caffeine in the organic solvent forms a complex with the aqueous solution, making it soluble in water.
2. Isolation:
Caffeine (in aqueous solution) + Dilute acid → Caffeine (in acid solution) + Water
In this step, caffeine is isolated from the aqueous solution by forming a water-soluble caffeine acid salt. By adding a dilute acid (such as HCl), caffeine reacts with the acid to form caffeine acid salt, which stays in the aqueous phase.
3. Recovery:
Caffeine (in acid solution) + Alkali/base → Caffeine (precipitate) + Water (solution)
To recover caffeine, the caffeine acid salt is treated with an alkali/base (such as sodium hydroxide - NaOH). It converts the caffeine acid salt back to caffeine, which precipitates out as a solid. The water-soluble salt byproduct remains in the aqueous solution.
4. Filtration and Drying:
Caffeine (precipitate) → Filtered residue + Caffeine (pure)
The precipitated caffeine is filtered out from the solution, leaving a residue. The residue is washed with water to remove impurities and then dried. The final product obtained is pure caffeine.
It's important to note that the specific compounds and solvents used in each step may vary depending on the extraction and isolation process. Different techniques, such as liquid-liquid extraction or chromatography, may also be involved in a more detailed caffeine extraction and isolation procedure.