Essential Oil Chemistry for Beginners - What Makes for Great Aromatherapy?

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? Their texture is different, and they don't leave tell-tale stains like the more familiar edible fixed like grape seed, sunflower, flax or hemp. 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.

Essential oils are 'volatile' oils - oils that DO easily evaporate. Their chains of carbon atoms to which the hydrogens attach are not as long or heavy, and are much more complex. Many essential oil structures are not really chains, but ring, or multi-ringed shapes with diverse sub-units - called 'functional groups' - sticking out in various directions. Like their fixed oil counterparts, essential oils are lipophillic - meaning 'fat liking'. The fat-liking nature of both fixed and essential oils makes them easily absorbed by our bodies. Because of their typically smaller structures however, essential oils are absorbed more rapidly than fixed oils, and can easily penetrate deep into the body. Their non-polar, fat friendly composition enables swift passage through mammalian cell walls, bringing the healing potency of plants into even the tiniest spaces.

Most of the therapeutic activity of an essential oil can be attributed to the functional groups of the individual chemicals that make up the oil. There can be over a hundred identifiable molecules in one essential oil. Each of these molecules, as mentioned earlier, is a chain or ring (or multiple-ring) structure of carbon atoms linked together with hydrogen atoms bonded to them in various configurations. Every chain or ring has a functional group attached - a functional group is defined by Salvatore Battaglia in 'The Complete Guide to Aromatherapy' as: "a single atom or group of atoms that...has a profound influence upon the properties of the molecule as a whole. It is often referred to as the chemically active center of the molecule".

As you can see, essential oils are really very complex in their chemical nature. There are nearly infinite possibilities of functional group and 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. When selecting between varieties of an essential oil, It IS helpful to know that any particularly oil is often composed of one or more primary molecular forms, with many minor or 'trace' constituents, and that ALL these molecules contribute to the oil's aroma and 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. If the starting plant material was grown in sub-optimal conditions or distillation was improperly performed, some secondary or trace componentes may not be present; this can result in a bland, lifeless aroma.

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 also 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. No one chemical can be singled out and used to give the same profound results as the complete pure essential oil.

So how is this synergy reflected in Lavender's aroma? Each of these chemicals has a unique smell; some are sweet, some are camphorous, some citrusy and some herbaceous. These notes act in perfect concert, in an exact formula, to produce the harmonious scent of a particular variety. And your nose knows this! One can tell the difference between a well-made, complex lavender oil with many notes within the aroma, and one that is flat or plain, which may be chemically imbalanced or missing some trace constituents.

Lavender grown at native higher elevations will often produce a greater percentage of linalyl acetate, which will result in a sweeter, more relaxing oil. Further, lower quality lavender plants may occasionally be sprayed with linalool before harvest to enhance the production of linalyl acetate by the flowers. While the end-product may smell sweeter, the process actually creates an imbalance in the overall healing synergy of the primary and trace molecules. All these oils will be labeled 'Lavender' on the store shelf, yet the finer, natural lavender will have a more beautiful, balanced aromatic bouquet, and is considered the most holistically healing variety by the world's leading aromatherapy practitioners.

This of course is not true of only lavender essential oil. All essential oils are subject to similar variations in production methods or the manipulation of their molecular make-ups through the addition of synthetic chemicals. For the most therapeutic benefit, it is always best to use true, carefully-made essential oils. To do this, find a source that is dedicated to supplying only the highest grades of oils. Examine their product's aromatic quality and business practices and so that you are comfortable with their dedication to your health, not just their bottom line. Listen to your intuition and your own nose; they won't lie to you! Practice, and you will continue to detect finer and finer differences in grades of the same variety. With even more education and skill, you'll start to recognize individual chemicals within an oils aroma, and make the best decisions as to which oils will have the most profound therapeutic affects for you, your family, or in your professional practice.