Extraction (chemistry)

The distribution of a solute between two phases is an equilibrium condition described by partition theory.

A solid sample containing the desired compound along with impurities is placed in the thimble.

An extracting solvent is chosen in which the impurities are insoluble and the desired compound has at least limited solubility.

After extraction is complete the solvent can be removed and the desired product collected.

Boiling tea leaves in water extracts the tannins, theobromine, and caffeine out of the leaves and into the water, as an example of a solid-liquid extraction.

Schematic of a separatory funnel showing two immiscible liquids, where 1 is any phase less dense than 2. Phase 1 is typically an organic solvent and 2 an aqueous phase.
Laboratory-scale liquid-liquid extraction. Photograph of a separatory funnel in a laboratory scale extraction of 2 immiscible liquids: liquids are a diethyl ether upper phase, and a lower aqueous phase.
Soxhlet extractor