Extraction

Chem mystery is more enchanting a title than chemistry. The biological processes that go on in life are in dynamic equilibrium - they happen in such a way that molecules come together and change form in irreversible process once a fixed energy storage level is achieved. These bio-molecules undergo chemical reactions at functional groups that are regenerated by the growth process - the deviations are part of the differentiation that makes life from a common pool of ingredients, swimming in water, an aqueous solution.

Once the process of plant growth has produced the vegetation containing the natural product of interest, the desirable compounds have to be removed from the plantaceous material, extracted and prepared for use.  The organic compounds that we want are produced inside of the cells, which require disruption of the cell wall and removal of the aqueous phase.  We are extracting the organic resins from the plant materials and rendering them as an oil.  This process can be used to extract essential oils from flowers and herbs - the process described here is for general application.  If chemistry intrigues you as a desirable skill set - sign up for a class at NWETI.com .

The key to getting a good volume of oil is to have as small an average particle size distribution as possible. By grinding the plant matter in a commercial kitchen blender, the cell walls are disrupted while the plant is still in solid form.  The grind can also be done by hand with a mortar and pestle. There is no need to dry the material before hand, as the process of extraction is set to remove the internal water that is major volume of the cell soup.  Like material dissolves like material - so the effort to maximize surface area will give the solvent molecules best access to the organics that we are extracting.

The choice of solvent is not trivial.  Alcohols will be more likely to take up water soluble compounds because of the functional group similarity. Both iso-propanol and ethanol come with additional water and can solubilize chlorophyll and other non-desired materials.  Organic solvents like Naphtha and Hexane that have no functional groups will take up the ring structures of the steroids and other molecular intermediates that make the essential oil.  The solvent is chosen to boil at a lower temperature than water.  Because of potential toxicity concerns, solvents should be used in either well ventilated areas or closed cooking systems.

A pound of herbaceous material and a gallon of solvent should be more than enough.  Powder the herb and place into an empty five gallon cooking pot.  Add enough solvent to cover the plant and then cover the container in such a way to create a seal.  Plastic trash bags seal perfectly.  Place this container into a turkey roasting pan filled halfway with water (enough to have the boiling water outside cook the solvent inside).  A short length of rope should go in the turkey roaster to keep the base of the pot from direct connection to the stove burner.  Cook for 4 hours.

Pour the material through a screen and decant the solvent away from the residue.  Take the residue back up in fresh solvent and repeat the cook process.  Combine the two extracts and remove the solvent using a simple distillation process.  The solvent comes off of the oil rapidly at first, but slows down as the mass percent decreases.  The oil is very viscous and can be swirled by hand to enable greater solvent removal.  A rotary evaporator works best; this requires a vacuum pump and laboratory set-up. 

Two washes of the material should provide a decent amount of oil - with lavender, the yield ran about 2 oz of oil for the pound of plant matter.  Greater yields come with familiarity of process; do not be surprised to not get a whole lot the first time.  As the world comes together in the spirit of unity, our skill sets can enhance our abilities to render natural resources into useful materials in partnership with Gaia!  To learn to leave a soft footprint, but extract value is one of the things that an understanding of chemistry can enhance.

Namaste' ...doc