Extraction of Caffeine from Tea Leaves
Extraction of Caffeine from Tea Leaves
Department of Biological Sciences, College of Science
University of Santo Tomas
España, Manila, 1028
ABSTRACT:
Caffeine is a white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants. It is most commonly consumed by humans in infusions extracted from the seed of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. The water soluble materials in the tea leaves are extracted into hot water. The hot solution is allowed to cool and the caffeine is then extracted from the water with dichloromethane (methylene chloride), which is an organic solvent that is insoluble in water. Since caffeine is more soluble in dichloromethane than it is in water, it readily dissolves in the dichloromethane.
This experiment is aims to isolate crude caffeine from tea leaves. The purity of caffeine is determined through melting point determination, the comparison of melting points of an unknown substance and a pure substance, and the comparison of physical characteristics.
I. Introduction
Extraction is a chemical method of separating a specific component of a solution from the rest of the solution. This is done by using a solvent in which the substance to be isolated is very soluble, while the rest of the solution is not as soluble.
Tea leaves consist mostly of cellulose, a water‐insoluble polymer of glucose, which is a monosaccharide. Cellulose performs a function in plants similar to that of fibrous proteins in animals: it is structure building material. Along with the cellulose are found a number of other things including caffeine, tannins (phenolic compounds, compounds that have an ‐OH directly bonded to an aromatic ring) and a small amount of chlorophyll. The group was tasked to take 5 bags of commercially sold tea (caffeinated) and to boil
Department of Biological Sciences, College of Science
University of Santo Tomas
España, Manila, 1028
ABSTRACT:
Caffeine is a white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants. It is most commonly consumed by humans in infusions extracted from the seed of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. The water soluble materials in the tea leaves are extracted into hot water. The hot solution is allowed to cool and the caffeine is then extracted from the water with dichloromethane (methylene chloride), which is an organic solvent that is insoluble in water. Since caffeine is more soluble in dichloromethane than it is in water, it readily dissolves in the dichloromethane.
This experiment is aims to isolate crude caffeine from tea leaves. The purity of caffeine is determined through melting point determination, the comparison of melting points of an unknown substance and a pure substance, and the comparison of physical characteristics.
I. Introduction
Extraction is a chemical method of separating a specific component of a solution from the rest of the solution. This is done by using a solvent in which the substance to be isolated is very soluble, while the rest of the solution is not as soluble.
Tea leaves consist mostly of cellulose, a water‐insoluble polymer of glucose, which is a monosaccharide. Cellulose performs a function in plants similar to that of fibrous proteins in animals: it is structure building material. Along with the cellulose are found a number of other things including caffeine, tannins (phenolic compounds, compounds that have an ‐OH directly bonded to an aromatic ring) and a small amount of chlorophyll. The group was tasked to take 5 bags of commercially sold tea (caffeinated) and to boil
References: Bayquen, A.V., Cruz, C.T., et al (2009).Laboratory Manual in Organic Chemistry. Quezon City: C&E Publishing Inc. Experiment 6: Isolation of caffeine from tea leaves. (n.d.). Retrieved from http://employees.oneonta.edu/knauerbr/chem226/226expts/226_expt06_pro.pdf Mann, FG & Saunders, BC (1960) Practical Organic Chemistry (4th ed), Longman, London, p.387 Selinger, B (1978) Chemistry in the Market Place (2nd ed), John Murray (Publishers) Ltd, London p415-7