Delos Reyes, K., Dizon, G.J., Enriquez, J.R.,
Estrada, G. and Garcia C.
Group 4 2G Med Tech Organic Chemistry Laboratory
Caffeine was extracted from dried tea leaves by multiple extraction technique. 10g of tea leaves was boiled in a solution of 4.4 g anhydrous sodium carbonate and 100ml distilled water and was extracted three times using 20 ml of dichloromethane. Theresidue was collected by decanting the mixture of organic extract and anhydrous sodiumsulfate and evaporating it to dryness. The percentage yield was computed by getting theratio of the weight of the crude caffeine (residue) and weight of the tea leaves used. Thepercentage yield was 0.92.
Extraction is a method of seperation in which a solid or solution is contacted with a liquid solvent (the two being mutually insoluble) to transfer one or more components into to the solvent. There are two main types of extraction in chemistry, namely: Liquid-liquid extraction or solvent extraction, which is divided into two types. (simple and multiple) and solid-liquid extraction. The type of extraction that was used in this experiment was the solid-liquid extraction. To extract the caffeine from the dried tea leaves, to know the amount of caffeine present in the 10 g of tea leaves and to calculate the percentage yield of caffeine in the 10 g of tea leaves were the objectives of this experiment.
A. Samples used
10 g of dried tea leaves, 100 ml water, 60 ml dichloromethane and about 4.4 g of anhydrous sodium carbonate were used in this experiment. B. Procedure
1. Weight of specimen (before extraction)
The weight of tea leaves used and empty evaporating dish was obtained using an analytical balance.
Fig. 1. Extraction set-up
A solution of 4.4 g anhydrous sodium carbonate and 100 ml distilled water in an Erlenmeyer flask was heated in a water bath...