Essential oils and extracts are made up of a number of chemical compounds that are either actively passively influencing the properties and quality of our products. The chemical family of a specific chemical compound can help provide a good understanding of some therapeutic properties for the compound in question. Of course not all chemical families trend the same way, but we can still learn a lot by understanding the broad chemical scope of each subfamily. For example, not all monoterpenes behave the same way chemically or biologically, but knowing more about the more common trends in monoterpene chemistry can be beneficial for understanding how limonene may function in our system. By learning about these core chemical families below one can also begin to determine when a particular compound may be acting more or less like a different chemical family category. All the chemical families are synergistic in creating the therapeutic qualities we look for in essential oils or extracts, and by understanding each families broader role we can begin to blend recipes more accurately, or predict what affect individual constituents will have.
Monoterpenes: This chemical family is the most prevalent in essential oils. These compounds are light (lower molecular weight), volatile, and flow freely among the oil. These compounds comprise the front end (the first quarter) of most GC/MS analyses. For example, in most citrus oils, limonene is a great indicator of quality. This monoterpene makes up a majority of citrus plants and is a good indicator of the overall properties of the oil.
Sesquiterpenes: This type of chemical family has a larger molecular weight than the monoterpene family. These compounds are not as common in essential oils, but when present have exciting properties. Most of the synergistic healing pathways run through the sesquiterpene families. These compounds are less volatile and contribute less to the aroma of an oil. Caryophyllene is a great example of a sesquiterpene that has unique properties to help make a well-balanced oil.
Alcohols (Monoterpenols, Sesquiterpenols): By adding an alcohol functional group to these terpene hydrocarbon chains, the chemical effects are drastically different when comparing to the previous chemical families. An alcohol added to a monoterpene chain is often called a monoterpenol, and when adding an -OH (alcohol) group to a sesquiterpene backbone, the family is called a sesquiterpenol. These compounds have an added oxidation pathway and can lead to more synergistic effects. Linalool is a very prevalent monoterpenol and is commonly known to help reduce stress.
Ketones (Oxides): Chemically, a ketone is described as a double bonded oxygen atom that is usually isolated along a hydrocarbon chain (either monoterpene or sesquiterpene). These compounds are often linked to having some of the most oxidative effects and can lead to greater healing properties for essential oils that contain this family. Most ketones are very rare to find in plant material, but helichrysum is known to have some italidiones which are ketones that are linked to regenerative effects.
Esters: In the essential oil field esters are very aromatic and help provide many of the soothing smells that we are all accustomed to experiencing when smelling many of the floral oils. Acetates are what comprise most of the esters we find in plant materials. Along with being calming and soothing, esters also have the ability to be anti-inflammatory in many cases.
Aldehydes: This chemical family is not normally found in many essential oils, but when it is present it usually dominates the aroma profile. These compounds look a lot like ketones, but are bonded directly to a terminal hydrogen atom. These compounds are used to deter pests in some cases (citronellal) and are easily recognized by name as they have the -al suffix to denote their chemical composition.