[Sis290025]

I did a search on this subject on the this site, and I read the thread about the different procedures for carrying out the caffeine extraction. My question deals with the involved properties in the process of extraction. In the extraction of caffeine from tea, extraction is based mostly on physical properties, right? These properties include solubility, density, and phase changes , particularly when the separatory funnel is in use and in the sublimation apparatus?

Thank you.

[Yggdrasil]

Yes, most separations and extractions rely on the differences in the physical properties of compounds (e.g. melting/boiling point, solubilities, etc.).  The only chemical property that is frequently used in extractions is acidity/basicity.

[Sis290025]

I have a question about the crude caffeine's color after the evaporation process. Usually it is yellowish or greenish. Does this result from impurities, such as chlorophylls, or is it because of another chemical?

Thanks again.

[Yggdrasil]

IIRC, the caffeine should be white after sublimation.  The yellowish/greenish color indicates impurities, but I'm not sure what impurities they would be.

[mir]

Btw - Ever tried using instant coffee to extract caffeine? You know that coffee - You just add hot water, and it is finish. You can make a really concentrated water solution (extra extra strong coffee). Saves time on the lab :-) And better, while you do it - Have a coffee for yourself.