Extraction and Purification of Caffeine from Tea Leaves

CHEM 14CL SPRING 2006
(C) Conclusion
Report Guidelines for EXTRACTION AND PURIFICATION OF CAFFEINE FROM TEA
LEAVES EXPERIMENT
POST-LAB REPORT GUIDELINES - THIS IS A GROUP REPORT
Post-lab report must be written inside your lab notebook.
(i) Compare your % caffeine value to the reported value of about 2-4% caffeine content in tea leaves.
Explain what may cause the % to be differed (i.e. where the loss of caffeine may come from during the
experiments).
(ii) Compare experimental IR spectrum to literature IR spectrum (provided with the experiment #14
worksheets or you can download it online (see below)). What can you conclude about the purity of your
experimental caffeine product?
Note: If you don’t have the literature caffeine IR spectrum, go to the following Web site and download the IR
spectrum:
http://webbook.nist.gov/chemistry/
Do a NAME search on caffeine and there should be a hyperlink for the gas phase IR spectrum of caffeine.
(iii) Interpretation of caffeine product composition and purity from TLC results. Explain all your reasoning.
NOTE: Before answering part (iii), refer to the notes on TLC listed on the previous page of
this guideline.
Attach ALL the experimental spectra & the ORIGINAL experimental TLC plate with your
post-lab report.