Dichloromethane Lab Report

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BS1003 – Organic Chemistry Practical 1 Laboratory Report
Name: Tristan Chan Yew Kit, U1640436J (T8)
Effects of Dichloromethane(DCM) in Extraction of Caffeine from Tea Leaves
To investigate the ability for Dichloromethane(DCM), a moderately polar organic solvent, to extract aqueous caffeine molecules, originating from Tea Leaves suspended in water.
Caffeine, defined chemically as 1,3,7-trimethylxanthine (C8H10N4O2), is an alkaloid that can be found in tea leaves, coffee and many other plant species. The amount of caffeine in dry tea leaves varies from 2-5% between different species of plants. Caffeine has uses in the medicinal industry, with the ability to act as a vasodilator, diuretic, and aid in stimulation of the central
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Reflux condensation was performed with use of a heating mantle and retort stand. A total of 20 minutes was allocated for reflux, starting when the mixture first began signs of boiling(T0), to when the allocation of time was depleted(T20). The mixture was filtered into a 50mL conical flask, and 10mL of 100°C water. The extract was subsequently allowed to cool to room temperature, and decanted into a separating funnel.
Liquid-Liquid (Polar-Nonpolar) extraction of DCM
In a fume hood, 8.0mL of DCM was added to the separating funnel, capped and gently mixed. The cap was released periodically to prevent build-up of pressure within the funnel. The immiscible liquids were allowed to separate. Emulsions formed within the funnel were gently removed with use of a thin glass rod. DCM in the lower layer was drained into a clean and dry 50mL conical flask. The entire process was repeated twice
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Further purification steps post extraction could be carried out to further increase the purity of caffeine. For example, crude caffeine could be washed again with DCM and recrystallized to further remove any impurities, which was not included in this experiment.
This method of extracting caffeine ultimately produces less than ideal quantities and qualities of caffeine, and hence can be optimized to obtain purer caffeine in higher yields. The experimental design was to demonstrate the ability for DCM to extract caffeine, which supports the original hypothesis.
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[3] Tadelech Atomssa and A.V. Gholap. "Characterization of caffeine and determination of caffeine in tea leaves using uv-visible spectrometer." African Journal of Pure and Applied Chemistry 5.1 (2011): 1-8.
[4] O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Cambridge, UK: Royal Society of Chemistry, 2013., p.
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