Organic Chemistry (Practical) Lab 5 PDF

Organic Chemistry (Practical ) Week 5: Fall Semester 2024-2025 Course Name: Organic Chemistry I (Lab) Stage: 2 Lecture-note: 5 (Caffeine Extraction) Lecturer: Dr. Soma Majedi (Ph.D. in Organic Chemistry) Research Assistant: Dr. Saanaa Aza (B....

Organic Chemistry (Practical ) Week 5: Fall Semester 2024-2025 Course Name: Organic Chemistry I (Lab) Stage: 2 Lecture-note: 5 (Caffeine Extraction) Lecturer: Dr. Soma Majedi (Ph.D. in Organic Chemistry) Research Assistant: Dr. Saanaa Aza (B. Pharm.) Outline 1. Understanding the practical application of liquid-liquid extraction. 2. Applying principles of Organic Chemistry to isolate bioactive compounds and drugs. 2  Objective ✓ Demonstrate the isolation of caffeine from tea leaves using the liquid-liquid extraction technique. ✓ Provide hands-on experience with the concepts of solubility, partitioning, and solvent evaporation. ✓ Illustrate the role of pH adjustments and drying agents in improving the efficiency and purity of the extraction process. 3  Introduction to Caffeine Extraction Caffeine: A naturally occurring alkaloid found in tea, coffee, and other plants. ❖ Structure: A purine alkaloid with polar and non-polar properties. → → → ❖ Sharp melting point (~235–238°C) Purpose: Isolate caffeine using organic solvents and demonstrate partitioning principles. 4  Principles of Liquid-Liquid Extraction Separation of compounds based on solubility in two immiscible liquids. Distribution Coefficient: Determines compound partitioning. Target Compound: Caffeine, soluble in both water and organic solvents. 5  Procedure 1. Weigh 10 g of dried tea and 2 grams of either Calcium Hydroxide (Ca(OH)2) or Sodium Carbonate (Na2CO3). 2. Put them to a 250 mL beaker and add 200 mL distilled water. 3. Boil the mixture on a heater for 15–20 minutes, stirring occasionally (dissolve the desired caffeine in the dry tea leaves). 4. Pour the mixture into the funnel and allow it to filter the tea leaves completely. 5. Let the filtered solution cool to room temperature. 6. Note: Cooling prevents Chloroform from evaporating, ensuring accurate extraction. 7. Pour the solution into the separating funnel (decanting funnel) and add 50 mL Chloroform under a fume hood, close the funnel and gently invert it. 8. Note: Avoid vigorous shaking to prevent emulsion formation. 6  Procedure 10. Open the separating funnel (decanting funnel) carefully to release gas. 11. Allow the Chloroform to settle. 12. Separate the two layers, collecting the Chloroform layer. 13. Note: Chloroform has a higher density and forms the bottom layer. 14. Evaporate chloroform by placing it in a watch glass over a boiling water bath under a hood. 15. Once Chloroform evaporates, caffeine remains as white crystals (Appearance). 16. Weigh the caffeine to determine its amount (Yield). 17. Analyze caffeine via TLC or melting point analysis (Purity). 7  Key Learning Outcomes Concepts Covered: ✓ Partitioning in liquid-liquid extraction ✓ Role of pH adjustment in separation ✓ Solvent evaporation techniques Applications: ✓ Pharmaceutical extraction techniques ✓ Caffeine isolation for research or commercial purposes 8 1. Why is Sodium Carbonate added during the extraction process? 2. What factors influence the distribution coefficient in liquid-liquid extraction? 3. How would impurities affect the melting point of extracted Caffeine? 9  Practical Lab Manual of Pharmaceutical Organic Chemistry - I, Shivendra Kumar Dwivedi (2020), ISBN-13 978-93-88022-67-5 Introduction to Organic Laboratory Techniques: A Small-Scale Approach, Donald L. Pavia, Gary M. Lampman, George S. Kriz, Randall G. Engel, (2004), Second (2nd) Edition, ISBN-13 978- 1305253926 10