EXTRACTION SARTE, Mary Catherine SY, John Emmanuel UMEL, Allurie YAP, Franklin John YOU, Mary Christine ABSTRACT
Caffeine was extracted from dried tea leaves by multiple extraction technique. The extract of tea leaves was boiled in a solution of anhydrous sodium carbonate and 100 ml distilled water and was extracted three times using 20 ml of dichloromethane. The residue was collected by decanting the mixture of organic extract and anhydrous sodium sulfate and evaporating it to dryness. The percentage yield was computed by getting the ratio of the weight of the crude caffeine (residue) and weight of the tea leaves used.
Extraction is the process of obtaining a substance from a mixture or compound using chemical, physical, or mechanical means. The theory of extraction lies in the concept of immiscibility between two phases to separate a solute from the other phase. There are two main types of extraction in chemistry namely: Liquidliquid extraction (also known as Solvent extraction or Partitioning), which is further divided into two types (simple and multiple), and Solidliquid extraction. The type of extraction used in this experiment was Multiple Liquid-liquid extraction. In this experiment, the group should be able to attain the following objectives: (1) Extract caffeine from dried tea leaves. (2) Know the amount of caffeine present in the tea leaves, and (3) Calculate the percentage yield of caffeine of tea leaves. B.)Extraction A solution of 4.4 g. anhydrous sodium carbonate and 100 ml distilled water in an Erlenmeyer flask was heated in a water bath until the anhydrous sodium carbonate dissolved. 15.6g. of tea leaves contained in a tea bag was added to the mixture. The tea mixture was left to boil and upon the first sign of bubbles, the tea mixture was timed to boil for 10 minutes.
A.) Weight of specimen (before extraction) The weight of tea leaves used and empty evaporating dish was obtained using an analytical balance. Fig 1.1 Materials for Extraction The tea bag was removed from the Erlenmeyer flask and its excess liquid was collected by pressing it against the side of the flask using a glass rod. 20 ml dichloromethane was added to the aqueous solution in a separatoryfunnel. It was left to stand for 2 minutes (or more) until the separation between two layers was clearly visible. Fig 1.0 Weight of the Specimen
Fig. 1.4 Weight of the Caffeine after Extraction D.)Percentage yield The percentage yield was obtained by getting the ratio of the weight of the crude caffeine (residue) and the weight of the tea leaves used, then multiplying it by 100%. RESULTS AND DISCUSSION After subjecting the tea mixture tothe entire process of extraction, decantation, and evaporation, crude caffeine was successfully collected. 0.4 g. of crude caffeine was collected from 15.6 g. of tea leaves. A percentage yield of (insert) was computed after getting the ratio of the weight of caffeine (residue) and weight of tea leaves used then multiplying it by 100%. This means that for every 15.6 g. of tea leaves, an amount of 0.4 g. of caffeine can be collected using the technique of multiple liquid-liquid extraction and this 0.4 g. of caffeine constitutes of the tea leaves.
Fig. 1.2 Procedure of the Experiment The organic layer was drained into a clean Erlenmeyer flask and the aqueous layer was discarded. This procedure was repeated for three times and all the organic layers obtained were combined. Half a spatula of anhydrous sodium sulfate was added to the extract in an Erlenmeyer flask. The solution was decanted onto a tared evaporating dish and was evaporated to dryness.
Fig. 1.3 Organic Phase and Aqueous Phase C.)Weight of specimen (after extraction) The weight of the evaporating dish containing the crude caffeine (residue) was obtained using an analytical balance. The weight of the crude caffeine was obtained by subtracting the weight of the empty evaporating dish to the weight of the evaporating dish containing the crude caffeine (residue). Fig. 2 (Schematic Diagram)
Date accessed: 07/ 27/ 2009 9:01 P.M. http://www.thefreedictionary.com/extraction Date accessed: 07/ 27/ 2009 8:56 P.M. http://www.tutorbene.com/cms_images/LIQUIDLIQUID%20EXTRACTION.bmp
WEIGHT OF TEA LEAVES USED
WEIGHT OF EMPTY EVAPORATING DISH + WEIGHT OF CRUDE CAFFEINE (RESIDUE)
15.60 g 112.20 g
WEIGHT OF EMPTY EVAPORATING DISH WEIGHT OF CAFFEINE (RESIDUE) Percentage Yield
111.80 g 0.40 g
Date accessed: 07/ 27/ 2009 9:19 P.M.
Table 1.0 Data Obtained Computations: % Yield= wt. of residue _______________ Wt. of tea leaves = 0.40 g _______________ 15.60 g 2.564% or 2.56%
BOOKS Bell, Charles. Organic Chemistry Laboratory with Qualitative Analysis Standard and Microscale Experiments.3rd ed. California, U.S. Holland, C. (1975). Fundamentals and modeling of separation processes : Absorption, distillation, evaporation, and extraction. Englewood Cliffs, New Jersey: Prentice-Hall. Vollhardt, Peter. Organic Chemistry Structure and Function. 5th ed. New York: W.H. Freeman and Company, 2007. 968-969. (2010). CUBoulder Organic Chemistry Undergraduate Courses. Retrieved July 16, 2010, from CUBoulder, Colorado. WEBSITES http://www.chemicool.com/definition/extraction.html Date accessed: 07/ 27/ 2009 8:58 P.M. http://orgchem.colorado.edu/hndbksupport/ext/ext.ht ml