Chemistry Myths and Misunderstandings

Who am I and why am I here?

Dr. Sue Clarke i

Introduction  In the 1980s I couldn't find a suitable book on essential oil chemistry so had to write my own.

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A Lightning Tour

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Background to Scientific Approach 2.

The Chemistry 3.

How Do We Make Decisions ?

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Suffering from Information Overload ?

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Getting Things Into Perspective iii

Science  A systematic study of nature and behaviour of materials and the physical universe based on observation, experiment and measurement.

◦ Evidence based knowledge  Science, especially chemistry, underpins the fundamental ideas and issues important for aromatherapy 1(1)

Science: Risk versus Benefit  Are we, and society in general, risk averse?

 Regulations, Guidance and Safeguards – ◦ Health & Safety, COSHH, IFRA. RIFM, MHRA 1(2)

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Science: NATURAL SUBSTANCES versus CHEMICALS  People say the strangest things … 1(4))

Science: CAM versus MAINSTREAM MEDICINE  The importance of the House of Lords Science and Technology report on CAM in 2000 and it's implications 1(5)

Science: Issues  Are risk v benefit, natural v chemical and CAM v mainstream medicine polarised views ?

 Overlap and mutual support  What is a natural product ?

 Do you agree with the definition of an essential oil as : ◦ The totally volatile product extracted by a physical process from a single plant species that has an odour and composition characteristic of an essential oil from that species.?

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Chemistry  Chemistry is a vast subject that takes many years of study building up on underpinning knowledge.

 Using IFPA syllabus will give you some background.

 The molecules found in aromatherapy are part of the branch of chemistry called ORGANIC CHEMISTRY. ◦ This is the chemistry of Carbon.

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Chemistry  Molecules found in essential oils can be CLASSIFIED in a number of ways. The most commonly used is based on the structures of the molecules based on hydrocarbons called TERPENES and their derivatives.

 The basic structural unit is called isoprene. It is a monomer and 'reacts' with itself to form larger polymers.  But isoprene is not the unit in the plant that gives rise to the terpene molecules.

 They form in the plant in a series of biochemical reactions called the MEVALONIC pathway which manufactures secondary metabolites.

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CHEMISTRY

Isoprene 2(4)

Chemistry: Terpenes  2 isoprene units give MONOTERPENES with 10 C atoms eg myrcene, limonene  3 isoprene units give SESQUITERPENES with up to 15 C atoms eg farnesene,cedrene  4 isoprene units give DITERPENES with up to 20 C atoms eg camphorene  The terpenes have names ending in ENE 2(5))

Chemistry: Terpenoids  ◦ ◦ The TERPENOIDS are compounds derived from the hydrocarbon terpenes but have an oxygen atom bonded into their molecules. They are arranged into FUNCTIONAL GROUPS (characteristic reactive parts of molecules) such as ◦ alcohols OH ( names ending in ol) ◦ ketones C=O (names end in one) aldehydes CHO (names end in al ) esters COOC (names end in ate or acetate)   Named after the terpene and the functional group eg linalool & geraniol are monoterpene alcohols linalyl acetate is a monoterpene acetate (ester) 2(6))

Chemistry: Functional Groups  Important for the reactions and characteristics of compounds.

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Linalool

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Linalyl Acetate

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Chemistry: What’s in a Name ?

   Many different and complex names for the same compound eg. C 12 H 20 O 2 Systematic (IUPAC) 3,7-dimethylocta 1,6-diene-3-yl acetate. Trivial linalyl acetate, linalool acetate, bergamol, bergamiol, acetic acid linalool ester, linalol acetate, lynalyl acetate and another 81 recorded names. 2(10)

Chemistry: Analysis  Quantitative and Qualitative  GC Gas Chromatography  MS Mass Spectrometry  Criteria for identification and purity 2(11)

Chemistry: Shapes of Molecules  Key action at membrane/cell surfaces  Many theories for sense of smell but specific binding with receptors important 2(12))

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Chemistry: The SIZE of Molecules  Larger are less soluble, less volatile, less able to pass through membranes.

 The skin barrier.

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Chemistry: Variation in Natural Products  Due to Species of the plant  Growth conditions – soil, climate, water availability, altitude  Chemotypes  Age of plant  Part of plant used  Extraction and processing method 2(15)

Chemistry: Storage Conditions  Sunlight  Temperature  Storage vessels  Exposure to atmosphere 2(16)

How Do We Make Decisions?

 Who and what can we believe ?

 Lots of terminology and definition 3(1)

Decisions: What is an Expert?

 What exactly is meant by Studies; Research; Investigations ; Trials ; Observations?

 Who is carrying out the work ?

 How are the results evaluated ?

 Publication of work & peer reviews  Statistics 3(2)

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Are You Suffering From Information Overload?

 Choice of materials  What can you trust ?

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Getting Things Into Perspective  Get qualified  Follow professional guidelines  Choose your supplier carefully  Common sense 5(1)

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Perspective • Keep an open mind • Embrace change and progress • Be philosophical – Socrates • Don't forget the human factor 5(3)

True wisdom comes to each of us when we realise how little we understand about life, ourselves and the world around us.

Socrates 469 – 399BC 5(4)