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The crude caffeine has a green tinge9/3/2023 Caffeine is an alkaloid, and more specifically, a member of the methlxanthines. It can be isolated from natural sources like tea leaves, cola nuts and cacao beans. The sublimed caffeine had a melting point range of 231.2-234.6 0C.Ĭaffeine is a common substance and is found in coffee, tea, soft drinks and chocolates. 13% of pure caffeine was recovered after sublimation. The tea bag yielded 0.031g of crude caffeine, which is about 1.3% of the mass of tea in one tea bag. Sublimation was used to extract pure caffeine from the impure. This suggested that it contained impurity. The impure caffeine had a melting point range of 223.6-229.3 0C. Caffeine do not vaporizes at this temperature because it has a boiling point of 178 0C and a melting point of 238 0C. Because of low boiling of methylene chloride, it vaporizes at 40 0C and impure caffeine crystals were collected. The resulting dry mixture was evaporated by heating. A micro pipet was used to transfer the organic layer to a flask. The organic layer separates to the bottom because methylene chloride is denser than water. The salt is soluble in aqueous solution therefore, it does not separate into the organic layer. Because of their phenolic groups and acid formation after hydrolysis, they can react with sodium carbonate to form a salt. Tannins have a phenolic group and also hydrolyzes to form an acid. Tannins are a class of compounds that have certain properties in common. This was done to form a sodium salt derivative of tannin compounds contained in tea. Sodium carbonate was also added to the mixture. This is because caffeine is more soluble in methylene chloride than in water. Caffeine isolation was accomplished from the mixture using methylene chloride. The resulting mixture was collected for the extraction of caffeine. During the experiment, a tea bag was heated in boiling water for about 15 minutes. The purpose of this experiment was to determine the yield, percent recovery and melting point of caffeine isolated from tea bag.
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