Extraction Isolation of Caffeine from Tea and Cola Syrup

Extraction Isolation of Caffeine from Tea and Cola Syrup 

After a chemical reaction has been carried out the organic product is often separated from inorganic substances by liquid/liquid extraction. For example, in the synthesis of 1-bromobutane (Chapter 15) 

1-butanol is heated with an aqueous solution of sodium bromide and sulfuric acid to produce the product and sodium sulfate. The 1-bromobutane is isolated from the reaction mixture by extraction with ether, a solvent in which 1-bromobutane is soluble and in which water and sodium sulfate are insoluble. The extraction is accomplished by simply adding ether to the aqueous mixture and shaking it. The ether is less dense than water and floats on top it is removed and evaporated to leave the bromo compound free of inorganic substances. 

The solvent used for extraction should have many properties of a satisfactory recrystallization solvent. It should readily dissolve the substance to be extracted it should have a low boiling point so that it can readily be 

1 Soxhiet extractor. For exhaustive extraction of soiid mixtures, and even of dried ieaves or seeds, the soiid is packed into a fiiter paper thimbie. Soivent vapor rises in the iarge diameter tube on the right, and condensed soivent drops onto the soiid contained in the fiiter paper thimbie, ieaches out soiubie materiai and, after initiating an automatic siphon, carries it to the boiiing flask where nonvoiatiie extracted material accumulates. The same solvent is repeatedly vaporized substances of very slight solubility can be extracted by prolonged operation. 

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