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VOLATILE OILS
 Are
volatile in steam
 Differ entirely from fixed oils in both chemical
and physical properties.
 Frequently associated with other substances
such as gums and resins.
 Tend to resinify on exposure to air.
 They are secreted in:
A.
B.
C.
oil cells.
secretion ducts or cavities.
glandular hairs.
Essential oils are consumed in numerous uses;
they are used :
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For their therapeutic actions.
For flavoring, e.g. oil of lemon.
In perfumery, e.g. oil of rose
As starting materials for the synthesis of other
compounds, e.g. oil of trupentine
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•
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As inhalations, e.g. eucalyptus oil.
Orally, e.g. peppermint oil.
As gargles & mouthwashes, e.g. thymol.
Transdermally
In aromatherapy, e.g. lavender, rosemary & bergamot
Oils with a high phenol content, e.g. clove and thyme have
antiseptic properties.
Oils showing antispasmodic activity. e.g. fennel,
mentha,chamomile, anise, rosemary.
Whereas others are used as carminatives.
Used in food preservation & cosmetic preparations.
NOTE
carminatives means: either prevents formation of gas in the GIT
or facilitates the expulsion of gas.
 Volatile
oils are generally mixtures of hydrocarbons
and oxygenated compounds derived from these
hydrocarbons.
 The
odor and taste of volatile oils is mainly
determined by these oxygenated constituents,
which are to some extent soluble in water but more
soluble in alcohol.
NOTE
Rose water & tinctures of lemon
CH3
CH3
CH3
O
OH
OH
H3C
CH3
Menthol
(peppermint oil)
H3C
CH2
Carvone
(caraway oil)
H3C
CH3
Thymol
(thyme oil)
OCH3
OH
OCH3
CH2
Eugenol
(clove oil)
CH3
Anethole
(anise oils)
CHO
Cinnamaldehyde
(cinnamon oil)
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1.
2.
3.
4.
They possess characteristic odors.
They are characterized by high refractive indices.
Most of them are optically active.
Their density is generally lower than that of water
(except for sassafras, clove & cinnamon oils).
5. May darken in color when exposed to light.
6. They are immiscible with water, but they are sufficiently
soluble to impart their odor to water. The aromaticity of
water depend on this slight solubility.
Essential oils are prepared by:
A. Distillation.
B. Scarification and expression.
C. Extraction.
D. Enzymatic hydrolysis.
E. Enfleurage.
There are three basic types of essential oil distillation:
1. water or "hydro-distillation"
2. water and steam or "wet steam"
3. steam or "dry steam“
1- Hydro-distillation in this method the plant material is
immersed totally in boiling water. The disadvantages are
that the heat is difficult to control and hence the rate of
distillation is variable. Also there is a possibility for
overheating and "burning" which lead to a poorer quality
oil.
2- Water/steam distillation the plant material is placed on a grid
which keeps the plant material above the water level. The
water is boiled below the grid and "wet" steam passes
through the plant material. Over packing of the still can
cause the steam to leave parts of the plant un-extracted.
3- Steam Distillation by direct steam provided from a separate
boiler. The still contains a grid plate under which an open
steam pipe is fitted. The advantages of "dry" steam
distillation are that it is rapid, therefore it is less likely to
damage those oils. Most advanced type of distillation
These are mechanical techniques carried at room
temperature.
Used in preparation of heat sensitive oils.
Process:
Squeezing of the plant material under water stream which
yield a mixture of essential oil, water, cellulose, wax and
other substance.
Removal of water an cellulose by centrifugation.
Removal of wax by chilling followed by feltration.
For preparation of delicate flowers oils which
contain either small amounts of oils or heat
sensitive oils
Classified into:
I. Non-volatile solvent extraction.
II. Volatile solvent extraction.
III. Extraction with supercritical gases.
For glycosidic volatile oils e.g. mustard oil.
Principle:
1. Subjecting the plant material to enzymatic hydrolysis to
liberate the volatile constituents.
2. Separation of the volatile constituents by distillation or
extraction.
3. Purification of the products.
Used to extract oils utilized in perfumery.
Process:
• A glass plate is covered with a thin coating of
especially prepared and odourless fat.
• The freshly cut flowers are individually laid on
to the fat which in time becomes saturated
with their essential oils.
• The flowers are renewed with fresh material.
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Carrier oils AKA fixed or base oils; are the oily non volatile part
of the plant, typically obtained from the seed or nut. They are
called ‘fixed’ as they have large molecules that do not evaporate
like the essential oils.
Several points differ between volatile oils and fixed oils:
1. Volatile oils can be distilled from their natural sources.
2. Volatile oils do not consist of glyceryl esters of fatty acids.
Hence, they do not leave a permanent grease spot on paper
and cannot be saponified with alkalis.
3. Volatile oils do not become rancid as do the fixed oils, but
instead, on exposure to light and air, they oxidize and resinify.
Origin:
Clove consists of the whole flower buds of Syzygium
aromaticum . F. Myrtaceae.dried until they become
reddish-brown.
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Morphology
The flower bud is reddish-brown and consists of a
quadrangular stalked portion, the hypanthium, 10 mm
to 17.5 mm long, surmounted by four divergent lobes of
sepals which surround a globular head .The head is
globular and dome-shaped, composed of four
imbricated petals
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The powder is dark brown and has strong aromatic spicy
agreeable odour and warm spicy agreeable taste Examine under
a microscope The powder shows
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epidermis and underlying parenchyma
Large oil glands
short fibers occurring singly or in small groups
with thickened, lignified walls .
abundant of parenchyma containing
cluster crystals of calcium oxalate
numerous triangular pollen grains
Xylem vessels and fibres.
Note : prisms of calcium and Starch granules are
absent.
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Uses
relieve pain and to promote healing
flavouring industries (spice)
anaesthetic properties (for toothache)
Antispasmodic and carminative
In manufacture of vanillin.
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Active constituents
volatile oil (15 -20%) ,which contain eugenol (85%).
Pyrogallol tannin.
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Chemical test
sudan III → red colour.
FeCl3 → blue colour.
KOH: needle crystals of K eugenate.
Clove Stalks
Externally, they are brownish and rough .internally presence of
prisms of calcium oxalate and pseudo crystal sheath.
 Mother Cloves
This can be detected by the presence of much starch in
the seeds.
 Brown Cloves ( Expanded flowers)
 Exhausted Cloves
lighter than water
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Origin:
German chamomile is the dried flower heads of Matricaria
chamomilla, family Compositae
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Morphology
The flower head is almost hemispherical,
with hollow receptacle carrying two types
of small sessile flowers called florets:
ray florets and central or disc florets.
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 Active
constituents:
flavonoid glycosides.
volatile oil contains matricarin which converted to
chamazulene by heating.
 Uses
calm frayed nerves (tranquilizer).
carminative, antispasmodic.
local anti-inflammatory for sun burns
Chemical test: sudan III : red colour
 Origin:
Is dried ripe fruits of Pimpinella anisum F. Umbelliferae
 Morphology
Anise fruits are greyish brown, about 2-12mm. long, ovoid,They are broad
near the base, and taper gradually towards the apex, which is crowned with
a stylopod. Cremocarp separated into its meri-carps which usually remain
united and attached to a pedicel longer than the fruit. Each mericap
possesses five ridges, rough to touch due to presence of short, stout hairs
The powder is greenish-yellow or brownish-green.
 The powder have strong aromatic agreeable characteristic taste
and sweet strongly aromatic taste shows the following
characters:
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fragments of branched vitta usually
crossed by the cells of the endocarp
aleurone grains
micro-rosettes of calcium oxalate
non-glandular, unicellular warty hairs
Few fibres and pitted parenchyma
 Active
constituents
1. Volatile oil (2 to 6%) contain anethole
2. fixed oil and protein.
 Uses:
Carminative
flavoring agent
Stimulant
Chemical test: Sudan III
 Origin:
Cinnamon is the dried bark of cinnamomum zeylanicum,
Family Lauraceae, deprived of most of its cortex known as
Ceylon Cinnamon.
 Morphology
Cinnamon occurs as quills (single or double compound
quills ).1 meter in length.
powder:
a reddish brown powder with a
characteristic pleasant and aromatic
odour and taste, showing fragments of:
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fibres, they are thick-walled and lignified
with lumen and few slit-shaped pits.
thin-walled oil cells
Sclereids, isodiametric, thick wall, lignified,
the outer wall is less thickened than the
others.
Starch granules and needle crystals of
calcium oxalate.
Cork cells are rare
 Constituents:
1) volatile oil (0.5 -1 % ) (contains cinnamicaldehyde, eugenol)
2) tannin and mucilage
 Uses:
- Carminative
- Antispasmodic
- Mild astingent
- Flavoring agent.
The oil is also a powerful germicide
 Chemical
test: Sudan III, Rhuthenium red, FeCl3 and KOH
for eugenol
 Origin:
It is the dried bark of Cinnamomum cassia,Family
Lauraceae.
Morphology:
Chanelled pieces or Single quill up to 40 cm long, earthy
brown colour with patches of the thin grayish cork.
Powder:
differs than cinnamon in:
1. Odour is less delicate, taste as
cinnamon but slightly
mucilaginous.
2. Numerous fragments of cork
cells, polygonal with slightly
thick wall, contains reddish
brown content.
3. Fibres are shorter and thicker.
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Active constituents:
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Volatile oil consisting of Cinnamicaldehyde,no eugenol
is found
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Use
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The same uses as cinnamon bark
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Chemical test
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all as cinnamon but negative test for eugenol
 Origin:
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they dried from the leaves and flowering tops of
Mentha piperita F. Labiatae
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Powder
the powder is brownish-green. with an aromatic characteristic odour and an
aromatic taste followed by a sensation of cold in the mouth. It is characterized
microscopically by the presence
of fragments of:
cells of the epidermis having wavy
walls and diacytic stomata
 Glandular labiaceous hair, unicellular base
with multicellular head composed of 8-16 radiating cells
 Non-glandular hairs.
 Different types of xylem vessels,
fibres and wood parenchyma.
 Calcium oxalate crystals are absent
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1.
2.
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Active constituents
Volatile oil : chief components are menthol
Tannin
Uses:
4.
carminative and flavoring agent.
inflammation of the mouth and pharynx (oral preparations)
Menthol is used in pharmaceutical preparations as local antipruritic,
counter irritant and antiseptic.
Recently the oil is used for treatment of colitis.
1.
Chemical test: Sudan III
1.
2.
3.
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