Extraction of Crude Caffeine from Tea using Liquid-Liquid Extraction (PPT), Slides of Organic Chemistry

Download Extraction of Crude Caffeine from Tea using Liquid-Liquid Extraction (PPT) and more Slides Organic Chemistry in PDF only on Docsity! EXPERIMENT 5 Extraction of Crude Caffeine from Tea using Liquid-Liquid Extraction CHEM LAB1A GRP 4 INTRODUCTION Extraction of Crude Caffeine from Tea using Liquid-Liquid Extraction CHEM LAB1A GRP 4 Objectives: 1. Isolate crude caffeine from brewed tea by liquid-liquid extraction using hexane and diethyl ether extracting solvents. 2. Compare the extraction efficiency of the two extraction solvents. 3. Compare the extraction efficiency of crude caffeine by single and multiple extraction. MATERIALS AND PROCEDURES Extraction of Crude Caffeine from Tea using Liquid-Liquid Extraction CHEM LAB1A GRP 4 Safety Precautions: 1.Organic solvents are very volatile, toxic, and flammable. Review your material safety data sheets carefully before handling. 2.Work in a well ventilated area when handling solvents. 3.Do not work with organic solvents near an open flame. Materials and Apparatus: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction Sodium Carbonate Distilled water Set-up of Organic Solvents Procedures: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction In an isolated beaker, stir 20 mL of distilled water and 2 g of sodium carbonate until the Na2CO3 dissolves and boil. Remove the beaker from heat, remove the boiling stick, and add the tea bag. Squeeze out as much water from the tea bag using string of the bag or glass rod for support. STEP 1 STEP 2 STEP 3 Repeat the brewing process by boiling the tea solution and repeat steps 2 and 3. Transfer 10 mL of the brewed tea to a 20 mL test tube and cool to below 40°C. SINGLE MULTIPLE STEP 4 STEP 5 Transfer the organic layer using Pasteur pipette to a new 20 mL test tube containing around 2-3 micro spatula of calcium chloride. Swirl the test tube. Add more drying agent if calcium chloride clumps together. SINGLE MULTIPLE Filter the mixture into a pre-weighed Erlenmeyer flask to remove the drying agent. STEP 9 STEP 10 STEP 11 SINGLE MULTIPLE CaCl2 Solvent CaCl2 Add a wooden boiling stick and evaporate the solvent using a warm water bath at around 70°C. Determine the yield of caffeine. SINGLE MULTIPLE Compare the yield from the two extractions. STEP 12 STEP 13 STEP 14 Results and Discussion: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction Physical Appearance of Crude Caffeine: Powdery white Amount of caffeine extracted using diethyl ether. One extraction: 3.1mg Multiple Extraction: 18.2 mg Amount of caffeine extracted using hexane. One extraction: 0 mg Multiple Extraction: 9.331 mg Amount of caffeine extracted using chloroform. One extraction: 389 mg Multiple Extraction: 3064.9 mg Problems: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction 1. Why is caffeine extracted from an aqueous solution using organic solvents? Identify some of the properties of these organic solvents as observed from the experiment. Because, diethyl ether and hexane have higher solubility than water. • high volatility • non-toxic and non-flammable • low boiling point • immiscible with water • unreactive with solute • solute must be soluble in it • impurities should not be soluble in it Problems: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction 2. Which is the better extraction solvent? Explain. • Based on the previous results, chloroform is a better extraction solvent because it is the most polar. Caffeine is a polar compound and the amount of organic layer depends on the solubility of the extraction solvent. Diethyl ether is a better extraction solvent than hexane because it is slightly more polar. Problems: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction 5. What is/are the ways to avoid forming an emulsion with your extracting solvent? If an emulsion forms, what are the ways to help reform the two layers? • One of the easiest way to avoid emulation formulation is through gently swirling the solution. It can also be prevented through the addition of brine or salt water. If an emulation forms, add a small amount of a different organic solvent to break the emulsion. The use of filter paper or centrifugation can also be done. Problems: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction 6. If your tea solution is contaminated with a significant amount of hydrochloric acid, what would happen to the efficiency of the extraction? Explain. • The extraction will then be not highly efficient for the reason that caffeine is basic and HCl is an acid. It would generate a reaction that produces hydrochloric acid which makes it soluble in water. Problems: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction 7. The distribution coefficient of caffeine between dichloromethane and water is 4.6. Given a 50 mL saturated solution of caffeine, determine the percent recovery of caffeine in a single extraction using a 20 mL of DCM; and determine the percent recovery of caffeine when the extraction is done twice using two portions of 10 mL of DCM. CONCLUSION Extraction of Crude Caffeine from Tea using Liquid-Liquid Extraction CHEM LAB1A GRP 4 Conclusion: EXPERIMENT 5: Extraction of Crude Caffeine from Tea using Liquid- Liquid Extraction References Extraction of Crude Caffeine from Tea using Liquid-Liquid Extraction CHEM LAB1A GRP 4