)2 Organic Chemistry Experiment Extract caffeine from tea Experimental center for chemical education
Extract caffeine from tea Organic Chemistry Experiment Experimental center for chemical education
Experimental purpose Learn to extract caffeine from tea by solid-liquid extraction and sublimation Master the use of soxhlet extractor Master the operation of distillation and sublimation devices
• Learn to extract caffeine from tea by solid-liquid extraction and sublimation • Master the use of Soxhlet extractor • Master the operation of distillation and sublimation devices Experimental purpose
2 Background introduction Tea contains a variety of alkaloids including caffeine about 1%0-5%, tannic acid(tannic acid)about 11%0-12%,as well as cellulose, flavonoid pigments proteins
Tea contains a variety of alkaloids, including caffeine about 1%-5%, tannic acid (tannic acid) about 11%-12%, as well as cellulose, flavonoid pigments, proteins… Background introduction
2 Background introduction Caffeine is a derivative of purine, which is weakly alkaline and has the effects of stimulating the heart, exciting the brain and diuresis Pure caffeine is white needle crystal, tastes bitter, and it is soluble in water ethanol. dichloromethane The melting point of caffeine is 238C When the caffeine containing crystal water is heated to 100 C, the crystal water is going to lose and sublimation will begin. The sublimation will be more remarkable at 120C, and if the temperature is 178C or higher, the sublimation process will be very fast CH C N O”N CH Caffeine purine (3,7-Dihydro-1, 3, 7-trimethyl-1-H-purine-2, 6-dione
• Caffeine is a derivative of purine，which is weakly alkaline and has the effects of stimulating the heart, exciting the brain and diuresis. • Pure caffeine is white needle crystal , tastes bitter, and it is soluble in water, ethanol, dichloromethane. • The melting point of caffeine is 238℃: When the caffeine containing crystal water is heated to 100 ℃, the crystal water is going to lose and sublimation will begin. The sublimation will be more remarkable at 120 ℃, and if the temperature is 178 ℃ or higher, the sublimation process will be very fast. purine Caffeine (3,7-Dihydro-1,3,7-trimethyl-1-H-purine-2,6-dione) Background introduction
2 Background introduction The extraction of caffeine from tea can be done by soaking method. Soaking method is a liquid-solid extraction. In the laboratory, a Soxhlet extractor can be used for such extraction The Soxhlet extractor for solid-liquid extraction involves three key points: the solvent reflux, dissolution and siphon, and these allow the solid tea to be extracted by a pure solvent each time Soxhlet extractor ilt Siphon The specific process is: heating the three-necked bottle will volatilize the solvent, and the solvent vapor will meet the condensate and drop back to the Soxhlet extractor, which can dissolve the caffeine from the tea. When the liquid level of Soxhlet extractor exceeds the height of the siphon, pressure caused by different liquid levels of the siphons two ends can make the solvent sucked back into the three-necked bottle Extraction device
• The extraction of caffeine from tea can be done by soaking method. Soaking method is a liquid-solid extraction. In the laboratory, a Soxhlet extractor can be used for such extraction. • The Soxhlet extractor for solid-liquid extraction involves three key points: the solvent reflux, dissolution and siphon, and these allow the solid tea to be extracted by a pure solvent each time. • The specific process is: heating the three-necked bottle will volatilize the solvent, and the solvent vapor will meet the condensate and drop back to the Soxhlet extractor, which can dissolve the caffeine from the tea. When the liquid level of Soxhlet extractor exceeds the height of the siphon, pressure caused by different liquid levels of the siphon’s two ends can make the solvent sucked back into the three-necked bottle . Background introduction Soxhlet extractor Siphon Extraction device