Essential Oil Chemistry: A Beginning Aromatherapy Primer
By: Ginger Robbins
Uh oh. Chemistry – the word itself can make one’s eyes glaze over. But wait, this is “essential oil chemistry’. MUCH more fun! While even beginning aromatherapy students are put off by the mere mention of the subject, they eventually realize the importance of understanding at least the fundamentals. The basics of essential oil chemistry will help you appreciate what gives a fine oil its unique aroma, help you more carefully discern a good oil from a second-rate one, and can improve your practice of using essential oils therapeutically. The greatest benefits of essential oils lies in their potential for true medicinal applications, where their antiviral, antimicrobial and anti-inflammatory properties are effectively utilized. And it is the understanding of their chemistry that enables the practitioner to select the right oils and use them most appropriately. Convinced? Well here’s a primer to get you started…
So, why are essential oils called “oils” anyway? They don’t feel greasy, and they tend to evaporate completely, unlike common “fixed” oils (such as olive, grapeseed, hazelnut and the like). Essential oils and fixed oils share a similar chemical foundation: their structures are based on the linking of carbon and hydrogen atoms in various configurations. But this is really where the similarity ends. Fixed oils are made up of molecules comprised of three long chains of carbon atoms bound together at one end, called a triglyceride. Every fixed oil is made up of just a few different triglyceride arrangements – olive oil, for example, is primarily made up of oleic, linoleic and linolenic acids (the names of particular carbon-hydrogen chains forming the triglycerides). Their long-chain shape holds them in a liquid state which does not easily evaporate.
Volatile oils are another matter – volatile oils do easily evaporate, due in-part to their smaller, more complex structures. Essential oils are a sub-category of volatile oils, essential oils being specifically those volatile oils that have been distilled directly from plants (rather than laboratory made, or from another otherwise “inorganic” source). Essential oils still have a core structure of linked carbon and hydrogen atoms, but they come in a great variety of shapes including short chains, rings and multiple-rings hooked together. Each of these core structures will have what is known as a “functional group” attached – a sort of “molecular sub-unit”. Despite their seeming complexity, though, essential oils are still very compatible with mammalian biology – their atomic structure allows them to penetrate into the deepest regions of our bodies, and even to the centers of our cells.
The therapeutic action of an essential oil is primarily determined by the “functional groups” found in the molecules that make up that oil. An essential oil is actually made up of many individual molecular constituents. Each of these natural chemicals is formed of a carbon-hydrogen structure with a functional group attached. It is the combination of the base structure AND the attached functional group that makes a single, unique molecule. And MANY of these unique molecules combine to form ONE essential oil.
As you can see, essential oils are really very complex in their chemical nature. There are nearly infinite possibilities of functional group and base ring or chain combinations. And ONE essential oil alone can be made up of HUNDREDS of these different molecular arrangements. Don’t worry, though! While it sounds complex, one needn’t know all the precise chemical details to use essential oils therapeutically. Just know that any single essential oil is comprised of a few natural chemicals that make up the bulk of the oil, and many minor “trace” constituents that also affect both aroma and therapeutic activity.
The best natural, undiluted, properly distilled essential oils with all the major and minor chemical constituents will have the finest aromas AND the most potent therapeutic action. Many factors in an essential oil’s production affect the total number and relative amounts of individual chemicals found in the final product. These include where the plant was grown, soil and climate conditions, time of harvest, distillation equipment, plus the time, temperature and pressure of distillation. This can give you an idea as to why two varieties of the same oil can smell so different: The full, beautiful bouquet of a fine essential oil will contain a myriad of notes, telling you that all natural components are present and in balanced amounts.
To best understand this, we’ll examine Lavender essential oil; more than fifty individual molecules have been identified in pure lavender essential oil. The aromatherapist must remember that ALL of these chemicals found in pure and natural Lavender oil work together to produce a therapeutic effect. For example, the linalool molecule is antiviral and antibacterial; the linalyl acetate is emotionally calming; other major components including cineol, limonene, pinene and others are all noted for specific biologic and aromatic activity. It is the combined, balanced, synergistic action of these chemicals that make pure, high-quality Lavender such a great healer.
What does this mean to the lay-practitioner? That it’s important to find a nice smelling lavender oil! Each individual chemical, both major and minor, has a distinct smell, and is talked about in terms of “notes” within the overall lavender aroma. Some of these are sweet, some citrusy, some are herbaceous, and some camphorous (and the list goes on). A precise amount of each will create a certain Lavender aroma. Some lavenders are more sweet (and may therefore more relaxing), others are more herbaceous. Your nose is an incredible detector of essential oil chemistry, and you’ll be surprised how effective it is at choosing the finest, most therapeutically valuable oil. Your nose can tell you if all the constituents are in balance, if the oil is fresh, and interestingly, also if the oil is right for you – trust yourself in this regard!
A balanced approach in aromatherapy, as in all of natural medicine, is best. The most effective practitioner will have a well-developed “internal pendulum” combined with a solid education. Significant variations exist in the quality of essential oils; it is really cost effective to buy the higher grades of oil, as their synergy of expertly distilled chemicals will have the greater therapeutic action. Use your nose, knowledge and intuition to find a source you trust, that delivers consistently high-grade oils for a reasonable cost. Use these same faculties to skillfully select and apply the appropriate oil for each circumstance. Essential oils are complex by nature; at the same time, they have an exceptionally broad scope of therapeutic applications. Hopefully, this little bit of aromatherapy chemistry will enrich your ability to support your own health, and the health of those around you.
About the Author
The author has made available reports on specific anti-microbials such as tea tree and other therapeutic essential oils.