Essential Oil Chemistry Prepared by Christine Rose

Atoms -The building blocks of matter Atoms are composed of 3 types of particles:  protons (positively charged)  neutrons (no electric charge)  electrons (negatively charged) Atoms become different elements depending on the number and ratio of these three particles.

The atom m.jpg

The basic elements of essential oils Hydrogen-H The smallest atom 1 proton 1 electron 0 neutrons Carbon-C 6 protons 6 electrons 6 neutrons Oxygen-O 8 protons 8 electrons 8 neutrons

 In order to become stable, most atoms bond to share electrons, and thus, form molecules.  Hydrogen, Oxygen, and Carbon form these covalent bonds.  In order to become stable, most atoms bond to share electrons, and thus, form molecules.  Hydrogen, Oxygen, and Carbon form these covalent bonds.

All essential oils start with hydrogen and carbon atoms. When 5 carbon atoms join in a branched chain- head to tail, the essential building block in plant biology is formed. This 5- carbon molecule is called an Isoprene unit

Hydrogen & Carbon 5 Carbon atoms form an Isoprene Unit Terpenes are the largest class of molecules in essential oils formed from isoprene units Monoterpenes composed of two isoprene units contain 10 carbon atoms Sesqiterpenes Composed of 3 isoprene units containing 15 carbon atoms Diterpenes Composed of 4 isoprene units contain 20 carbon atoms

Analgesic, bactericidal, expectorant, stimulant Examples: Camphene & pinene in cypress, terpinene in juniper Monoterpenes Analgesic, anti-allergic, anti-inflammatory, antiseptic, hypotensive, spasmolytic Farnesene in chamomile & lavender, Beta-caryophyllene in basil & black pepper Sesquiterpenes Antifungal, expectorant, hormonal balancers, hypotensive Sclareol in clary sage Diterpenes

An interesting fact: diterpene molecules are too heavy to allow evaporation in steam distillation, so are therefore rarely present in distilled essential oils!

So, now that we understand terpenes, let us add an oxygen atom or oxygen-containing functional group to this terpene molecule and we have a terpenoid molecule. Physical characteristics of terpenoid molecules are: They are very volatile-making inhalation an effective method for use. They are very flammable. They are generally less dense than water and will float on the surface.

Monoterpenes and sesquiterpenes are not soluble in water. The molecules in water (H2O) are polar and prefer to attract other polar molecules. Terpenoids are generally non-polar and, therefore, will be repelled and float on top of the water (or in the case of eugenol, which is more dense than water, will sink to the bottom). Vegetable oils, however, are also non-polar and will dissolve the lipophilic (fat-loving) terpenoids. Ethanol (alcohol in spirits) is another medium used to dissolve essential oils. This has the added benefit of dissolving itself in water.

Main actions Name Ending Examples Essential Oils Characteristics Alcohols Antiseptic, antiviral, bactericidal ol Borneol, cedrol, citronellol, geraniol, linalool peppermint, geranium Relatively stable Aldehydes Antifungal, anti- inflammatory, disinfectant, sedative al, aldehyde Citral, citronellal, geranial, valeranal lemongrass, Slightly fruity aroma, often cause skin irritation and allergic reaction AcidsAnti-inflammatoryic acid Benzoic acid, cinnamic acid Frankincense Rare in essential oils, generally low volatility Esters Antifungal, antimicrobial, sedative yl, ate Benzyl acetate, linalyl acetate clary sage, bergamot, lavender Often intensely fruity odor. Ketones Anticatarrhal, cell proliferant, expectorant, vulnerary one Camphor, carvone, jasmone, thujone, verbenone camphor, hyssop, rosemary, sage Stable compounds, relatively resistant to metabolism by the body Lactones Anti-inflammatory, antiphlogistic, expectorant, febrifuge one, in Bergapten, coumarin catnip, jasmine(low) Generally low volatility Oxides Expectorant, anti- inflammatory ole Cineole, linalol oxide, rose oxide eucalyptus, anise Possible respiratory irritation Phenols Analgesic, antiseptic, bactericidal, disinfectant, stimulant ol Carvacrol, eugenol, thymol, cresol bay, cinnamon, thyme, clove Very likely to be irritating. Terpenes Anti-inflammatory, antiseptic, antiviral, bactericidal Bergaptene, limonene citrus, pine, juniper Susceptible to spoilage