volatile oils Flashcards
(75 cards)
- odoriferous plant principles
- insect repellant & insect attractant
- composed of terpenoids - compounds having
isoprene unit (5C) as building blocks
– Thermal decomposition of terpenoids gives
isoprene as one of the product.
Volatile oils
states that the terpenoid molecules
are constructed from two or more isoprene unit.
– Isoprene rule
- compounds having
isoprene unit (5C) as building blocks
terpenoids
Volatile oils are also known as:
aka: Ethereal oils or Essential Oils or Essences
Standard Storage Conditions of volatile oils
stored in a dark,
cool place preferably in a full amber glass
container
Reasons for Storage conditions:
- Volatility
- Autooxidation
- Photosensitivity
Familiy: Lamiaceae
(Labiatae)
secretory structures: Glandular Hairs
Family: Piperaceae
secretory structures: Modified Parenchyma Cells
Family: Apiaceae
(Umbilliferae)
secretory structures: “Vittae” or oil tubes
Family:Rutaceae/
Pinaceae
secretory structures: Schizogenous/ Lysigenous
ducts
Physical Characteristics of volatile oils
Posses characteristic odor
* High refractive index - refractometry
* Optically active
* Immiscible in water but they can be sufficiently soluble
to impart their odor in water → aromatic waters
Difference between V.O. and F.O
*V.O. can be distilled
* V.O. don’t saponify
* V.O. don’t leave a greasy spot on paper
* V.O. don’t have glycerol as backbone
* V.O. don’t become rancid
- vehicle; requires fresh sample or samples which are resistant to
high-temp (Ex: Turpentine Oil)
Water
no active boiling of the sample, can be done on fresh or
dried samples (Ex: Cinnamon & Clove Oil)
H2O & Steam
-Peppermint & spearmint
– For fresh samples only
Steam distillation
Destructive Distillation – Disadvantage: formation of smoke-like/ burn-like odor (empyreumatic odor)
– Empyreumetric oils (heat w/o air access)
– Incineration: only Pinaceae & Cuppresiaceae
No vehicle
methods of distillation
*water distillation
*H20 and steam
*Steam distillation
*No vehicle distillation
2 methods of expression
- Ecuelle
- Enfleurage
a process involving a machine/ mechanical
device with spikes designed to puncture the oil glands
– preferable for citrus samples
Ecuelle
- involves the use of a fatty pomade which
absorbs the oil from the sample → Ethanol extract
Enfleurage
obtained through heat w/o air acces
Empyreumetric oils
- involves the use of organic solvents
- advantage: low BPs - the process can be done at a
much lower temp. w/o compromising the quality of the
oil - disadvantage: cost of solvents; some are toxic (e.g.
benzene)
Extraction
- Ex: Glycosidic volatile oils
- Sinalbin/ Sinigrin (Myrosin) –> Glycosidic
volatile oils
ENZYMATIC HYDROLYSIS
solid portion of V.O
STEAROPTENE