Titles of Experiments CHM556



CHM556

Experiment 1

Isolation of Caffeine from a Tea Bag

For background of this experiment, refer to experiment 11B, page 498 of the laboratory textbook: Introduction to Organic Laboratory Techniques, A Small Scale Approach, 3rd Edition by Engel, Kriz, Lapman and Pavia.

In this experiment, you will extract caffeine from tea bag. This is an example of isolation of a natural product utilizing acid base extraction technique. Read introductory part of experiment 11 carefully before proceeding to the actual procedure in experiment 11B.

Please review technique on Separation and Purification Scheme (4; pg 461) including Extractions with Separating Funnel (4A; pg 462).

Conduct the experiment as described in the laboratory text book with the following modifications.

1. Use a 100 ml beaker and 50 ml of water to make the tea solution.

2. Transfer the hot tea solution into a small conical flask. Then add 0.5 g of sodium carbonate.

3. Then filter the solution into a small separatory funnel. Use cotton for filtration not filter paper.

4. Add 15 ml of methylene chloride to the separatory funnel and start the extraction. You will need to wait for the emulsion to break.

5. Drain off the lower methylene chloride layer and add 10 ml of fresh methylene chloride. (Repeat this step 2 times).

6. Dry the combined methylene chloride layer using anhydrous sodium sulphate.

7. Transfer the dried methylene chloride solution into a pre-weighed small round bottomed flask and evaporate off the solvent using the rotary-evaporator.

Your report for this experiment should include:

a) The extraction scheme.

b) Percentage of caffeine in the tea.

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download