What is Hydrocarbon Extraction?

Hydrocarbon extraction uses hydrocarbon solvents to strip cannabis plant material of desirable compounds like tetrahydrocannabinol (THC), cannabidiol (CBD), and terpenes. These compounds are isolated into a concentrate and can be further refined to produce a wide variety of concentrated extracts, like cannabis oil, hash or wax. Butane and propane are the most popular choices of hydrocarbon solvents for the hydrocarbon extraction process, but each extracts subtly different ratios of cannabinoids and terpenes.

Both are non-polar, flammable, liquefied gases. They both have low boiling points, but propane’s is significantly lower (-43.6 °F vs. 31.1 °F). Propane’s low boiling point is excellent for preserving temperature-sensitive terpenes Propane, however, is much more expensive than butane and has a higher operational pressure. For this reason, it’s common to see blends of butane and propane in the hydrocarbon extraction process to get the best of both worlds. A gas mixture strips additional terpenes and purges more efficiently than butane alone.

How Does Hydrocarbon Extraction Work?

Solvents are substances that can dissolve other substances, molecules, and compounds. Water is probably the best-known solvent and is known as the “the universal solvent.” However, everyone is probably familiar with the fact that water is unable to dissolve oil. When mixed, oil will always eventually separate from water.

Water is a polar molecule, and oils (fats, lipids, and other hydrocarbons) are non-polar. “Likes dissolve likes” is a common phrase learned in chemistry class. It refers to the polarity of molecules; polar molecules are best at dissolving other polar molecules, and the same applies to non-polar molecules.

Polar molecules, like water, are polar because of their chemical makeup. Water is made up of two hydrogen atoms and one oxygen. Since oxygen is more electronegative than hydrogen, a partial negative charge develops around the oxygen atom, and partial positive charges develop around the hydrogen atoms. The partial charges make the water molecule (and other non-polar molecules) kind of like a magnet.

Non-polar molecules include everything from fats and lipids to oil and gas. Many of them are chains of carbon and hydrogen atoms (hence their name hydrocarbon). Carbon and hydrogen are comparable in electronegativity, so no partial positive and negative charges develop.