Learning Essential Oil Chemistry & the Role of Functional Groups

Marge is truly enjoying delving into your questions on Facebook each Monday night at 8:00 PM CDT for Mondays with Marge. 

Stacy brought up an important subject, Essential Oil Chemistry, which gave Marge the opportunity to introduce the wonderful world of Functional Groups to our friends and Aromatherapy enthusiasts.

Stacy: You sometimes hear the analogy, "I don't understand how my car works, but I can still drive." Along those lines . . . does a home user of essential oils need to know much chemistry of essential oils? (Given, of course, that we get our advice from trusted sources such as you!) What would you, ideally, like for your home users to read or understand about chemistry?

Marge: Stacy, the advantage of learning at least a little bit about chemistry is that you can make

wiser choices among oils, and in blending. Now, truth time, for years I ran the other way from any mention of EO chemistry. I couldn't wrap my brain around it, and didn't WANT to wrap my brain around it. And, instead of learning chemistry, I learned this oil does that, and that oil will do that...that that oil over there does THAT... and I am very good at keeping track of that, and can carry most of it around in my head. So, who needed chemistry? And if anyone asked WHY this oil does that? "Magic!"

Now, there is one "easier" way to learn chemistry... and that is called Functional Groups. It provides a format for classifying, "grouping" oils based on their chemical components. (Once upon a time, 20 years ago or so, I had a mentor who did not subscribe to the idea of Functional Groups, so neither did I.) 

For a lot of years, I was able to avoid dealing with functional groups, and with chemistry. I knew which oils were dangerous on the skin, which were sensitizers, which were anti-inflammatory, which were relaxing, etc. And THEN I was accepted into Jane Buckle's CCAP course, with Kathleen Duffy, even though I am not a health care practitioner. And, (drumroll, or gasp, take your pick), Kathy taught functional groups. Oh. Well, now, I have all the respect for Jane and Kathy in the world, and if THEY are teaching this... sigh. So, I had to let go of my firmly held opinion, and start to learn about Functional Groups. And then I took Mark Webb's Advanced Aromatic Medicine course, and HE taught functional groups. Slightly different terminology. What Jane and Kathy teach as alcohols, Mark teaches as terpinols (i.e. monoterpenols, etc.).  Jane and Kathy teach "sesquiterpine alcohols." But they all three refer to Geraniol, and citronelol and well, anyway.

"Functional group" chemistry isn't perfect, because there are some components that don't seem to fit inside the category. For example: SOME Ketones are dangerous, toxic. Thujone, Pulegone, for example. But, the Italidiones that make Corsican Helichrysum such a powerful scar healer are types of Ketones. So the categories and their descriptions don't always fit. But there are some that are amazingly useful.

For example: Esters. Esters are EO components ending in "ate" such as linalyl acetate in Lavender, etc. Roman Chamomile is the highest in esters of any commercially produced essential oil. It is the ESTER content that makes roman chamomile so relaxing. Most esters are very 'benign' and relaxing. There is one exception to that category though. Methyl salicylate is considered an ester. It is the major component in Wintergreen and Sweet Birch. This has all sorts of warnings. So you learn that MOST esters are relaxing and possibly antispasmodic, and you red flag the one major exception.

Then you look at what Mark calls the "monoterpenols" and Jane calls “monoterpene alcohols.” One of the functions of that group is germ killing. They are known to be "anti-infectious" and stimulating. and they tend to end in the letters, “ol.” Linalool (or Linalol, depending on which book you read.) Now, why does this matter?

You are shopping for Lavender. You want the Lavender for skincare; you've been told it will be helpful for acne. Do you want a Lavender that is high in linalyl acetate, the ester, for relaxation? or do you want the Lavender that is higher in Linalool to perhaps kill some of the bacteria that can be causing acne? THIS is why knowing at least some essential oil chemistry is helpful. It can help you make wiser choices in shopping, and in blending.

We recommend our CO2 extracted Frankincense oils for meditation, and as anti-depressants, because of their content of Incensole Acetate... an ester... "ate" that does not come across in the process of steam distillation, so only occurs in the CO2 extraction.

This is the sort of decision that knowing at least the outlines of Functional Group theory can help you make.

Now... we should go a step further. Each component, each grouping, is composed of elements. And there are drawings that will show you what a molecule of an alcohol, or an ester looks like. I still have a really hard time wrapping my head around those. I struggle with them. Do you need to know it? I don't know.

I am often asked to recommend a good Essential Oil Chemistry book which I rarely do.  First a caveat.  At all costs, avoid David Stewart’s book which is filled with disinformation.  Having said that, in Essential Learning files there are book reviews and I am comfortable suggesting these three: Essential Chemistry for Aromatherapy by Sue Clarke recommended by Mark Webb as a good Chemistry book and Sandy Barrett says it is very people friendly. The Chemistry of Aromatherapeutic Oils by E. Joy Bowles recommended by Mark Webb as an intro into Chemistry. The Chemistry of Essential Oils: An Introduction for Aromatherapists, Beauticians, Retailers & Students Hardcover – October, 1996 by David G. Williams Excellent Chemistry manual recommended by Mark Webb and Marge Clark. From Mark Webb: "brilliant text, well written & appropriate language & information for the target market."

Marge: Sandy Barrett, a nurse and fellow student in Mark Webb’s aromatic medicine class also shared her thoughts. Sandy says, “Forget the stick drawings, they'll drive you batty, and you aren't planning to be a chemist. The functional groups - you need to know what they are and their purpose. As a home user, you don't have to have every constituent memorized - google is a wonderful thing. So if you are looking at a gc and reading constituents, you can google and learn the functional group it belongs to, and thus, what to expect of it. Now, obviously 60% is going to give you more bang than, say, 2%, so there's that to consider.”

(Marge: I have a mental image of my Aussie mentor ringing my neck for this, but even he said numerous times, "people, you aren't chemists, don't get hung up on the chemistry. Your job is to know what the oils can do.")

Stacy: Wow, thank you Marge and Sandy! I'm anxious to give your answers some time and thought. So generous of you to share!