Higher Chemistry - Education Scotland

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Transcript Higher Chemistry - Education Scotland

Essential Oils
Learning outcomes

Essential oils are the concentrated extracts
of volatile, non-water-soluble aroma
compounds from plants.

Essential oils are widely used in perfumes,
cosmetic products, cleaning products and
as flavourings in foods.
Learning outcomes

Essential oils are mixtures of organic
compounds.

Terpenes are the key components in
most essential oils.
The history of essential oils

The benefits of essential oils have been
recognised for thousands of years.

Their use is described in the New
Testament of the Bible.

They were used in anointing rituals and in
healing the sick.
The history of essential oils

The ancient Egyptians used essential oils
for embalming, religious rites and
medicinal purposes.

King Tut’s tomb was found to contain 50
jars of essential oil when it was opened in
1922.
Modern uses
Cosmetics
Cleaning
Flavours
Dentistry
Essential oils
Adhesives
Insect
repellents
Medical
Perfumes
What are essential oils?

‘Essential’ refers to the fact that the oil carries
the distinctive essence (scent) of the plant.

Concentrated, volatile, non-water soluble aroma
compounds extracted from plants.

Contain no artificial substances, unlike
perfumes and fragrance oils.
Essential oils – composition

Essential oils are mixtures of organic compounds.

Terpenes are the key components of all essential
oils.
Essential oils – chemistry

The distinctive character of an essential oil can
be attributed to the functional group present in
its key molecule.

Esters, aldehydes, ketones and alcohols are all
found in essential oils.
Essential oils – perfume

The ester linalyl acetate is found in the essential
oil lavender.

This ester is often added to perfumes.
H3C
C
CH3
O
C
H3C
CH2
CH
O
CH3
C
CH2
Linalyl acetate
CH2
CH
Essential oils – cleaning

The essential oil known as lemon oil contains the
terpene d-limonene.

It is known for its ability to act as a natural solvent
and a Hcleanser.
C
CH
3
2
C
CH
H2C
CH2
H2C
CH
C
CH3
Limonene
(skin of citrus fruits)
Hospital cleaners

Certain essential oils kill bacteria and fungi
(including MRSA and E. coli) within 2 minutes of
contact.

Essential oils are blended into soaps and shampoos
used in hospitals to eradicate deadly ‘super bugs’.
Essential oils – cosmetics

The essential oil geraniol is added to some cosmetics
to balance and revitalise the skin.
CH3
CH3
C
H3C
C
CH2
CH
CH2
Geraniol
CH2
CH
OH
Essential oil – cold sores

Melissa oil contains the terpene citral,
which is used to combat cold sores.
CH3
C
H3C
CH
CH2
CH2
Citral
CH3
H
C
C
CH
O
Essential oils – toothpaste

The essential oil thymol has antiseptic properties.
CH3
C
HC
CH
C
CH
HO
C
CH
H3C
Thymol
CH3
Steam distillation

Steam distillation is one of the methods used to
extract essential oils from plants.

Steam passes over the plant and extracts the
essential oil.

The mixture evaporates and passes into the
condenser.

The essential oil vapour is chilled and collected.
Steam distillation
Essential oils – summary

Concentrated extracts of volatile, nonwater-soluble aroma compounds from
plants.

Widely used in perfumes, cosmetics,
cleaning products and flavourings.

Mixtures of organic compounds.

Terpenes are the key components of most
essential oils.