volatile oil

• Volatile oils


  Odoriferous plant principles
• Volatile oils


  • 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
  • Isoprene rule states that the terpenoid molecules are constructed from two or more isoprene unit
• Volatile oils


  Ethereal oils or Essential Oils or Essences
• Standard storage conditions for volatile oils

  Stored in a dark, cool place preferably in a full amber glass container
• Reasons for storage of volatile oils

  • Volatility
  • Autooxidation
  • Photosensitivity
• 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 volatile oils (V.O.) and fixed oils (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
• Methods of isolating volatile oils

  • Distillation
  • Expression
  • Extraction
  • Enzymatic hydrolysis
• Distillation

  1. Water - vehicle; requires fresh sample or samples which are resistant to high-temp

  2. H2O & Steam - no active boiling of the sample, can be done on fresh or dried samples

  3. Steam distillation - for Peppermint & spearmint, for fresh samples only

  4. No vehicle - Destructive Distillation - Disadvantage: formation of smoke-like/burn-like odor (empyreumatic odor)
• Expression

  1. Ecuelle - a process involving a machine/mechanical device with spikes designed to puncture the oil glands - preferable for citrus samples

  2. Enfleurage - involves the use of a fatty pomade which absorbs the oil from the sample → Ethanol extract
• Extraction


  1. Involves the use of organic solvents

  2. Advantage: low BPs - the process can be done at a much lower temp. w/o compromising the quality of the oil

  3. Disadvantage: cost of solvents; some are toxic (e.g. benzene)
• Enzymatic hydrolysis


  For Glycosidic volatile oils - Sinalbin/Sinigrin (Myrosin) --> Glycosidic volatile oils
• Components of volatile oil

  • STEAROPTENE - solid portion
  • ELEOPTENE - liquid portion
• Medicinal and commercial uses of volatile oils

  • Fabrication of perfumes - Top notes, Middle notes, Base note (fixatives : staying power)
• Sources of perfume ingredients

  • Musk - Dried secretion from the preputial follicles of the male musk deer of asia
  • Civet - A glandular secretion appearing outwardly discharging pockets of Civet cats (Paradoxus hermaphroditus)
  • Ambergris - Pathologic product formed in the stomach of sperm whale when it feeds on squid or cattle fish
• Terpenes/Terpenoids


  • Natural products whose structures are made up of isoprene units (C5)- building blocks
  • Compounds isolated from terpentine
  • Modern definition: 'Terpenoids are the hydrocarbons of plant origin of the general formula (C5H8)n as well as their oxygenated, hydrogenated, and dehydrogenated derivatives.'
• Classification of terpenoids


  • Acyclic Terpenoids
  • Monocyclic Terpenoids
  • Bicyclic Terpenoids
  • Tricyclic Terpenoids
  • Tetracyclic Terpenoids
• Classification of volatile oils

  • Hydrocarbon volatile oils
  • Alcohol volatile oils
  • Aldehyde volatile oils
  • Ketone
  • Phenol
  • Phenolic ether
  • Oxidative volatile oils
  • Ester volatile oil
• Hydrocarbon volatile oils

  • Limonene, P-cymene, Pinene (most commonly found in plants)
  • Sabin & Myrcene
• Turpentine oil

  • Contains pinene
  • Source: Pine Tree (Pinus palustris)
  • Rectified Turpentine Oil: distillation with an aqueous solution of NaOH
  • Terpinhydrate: or Terpineol - formed by the reaction of RTO w/ HNO3 in the presence of alcohol
  • Use: both preparations are used as stimulant expectorant
• Alcohol volatile oils


  • Acyclic: Geraniol, Linalool & Citronellol
  • Monocyclic: Menthol, α-terpineol
  • Dicyclic: Borneol
  • Sesquiterpene: Zingiberol
• Peppermint oil


  • SN: Mentha piperita
  • Japanese peppermint - SN: M. arvensis
  • Used as a source of menthol (by freezing the oil)
  • Synthetic menthol (racemic mixture)
  • Natural menthol (levo)
• Cardamom oil


  • SN: Elettaria cardamom
  • Chief Const: Cineole
• Coriander oil


  • SN: Coriandrum sativum
  • Const: Linalool
  • Use: Carminative
• Rose oil


  • CN: Otto of Rose
  • SN: Rosa gallica
  • Const: Geraniol, Nerol, Citronellol
• Orange flower oil


  • CN: Neroli Oil
  • SN: Citrus aurantium
  • Const: Linalool
• Juniper oil


  • SN: Juniperus communis
  • Const: Borneol
  • Use: OTC as diuretic (Odrinyl®)
• Pine oil


  Const: α-terpineol
• Cinnamon

  • Saigon - Cinnamomum laureini
  • Ceylon - C. zeylanicum
  • Cassia - C. cassia
  • Constituent: Cinnamaldehyde
  • Flavor, carminative, antiseptic
• Lemon

  • Const: Citral - combination of Neral & Geranial (responsible for the odor)
  • Common problem: Terebinthenate Odor (attributed to the terpene content)
  • High quality: Terpeneless Oil (95% of terpenes are removed)
• Orange oil (Sweet orange)

  • SN: Citrus sinensis
  • Const: Decanal
  • Chief const: Limonene (HC)
• Citronella oil

  • SN: Cymbopogon nandus
  • CN: Tanglad
  • Const: Citronellal - mosquito repellant action
• Hamamelis

  • Const: 2-hexen-1-al
  • Use: OTC for hemorrhoids (astringent property)
• Ketone volatile oils


  • Monocyclic: Menthone, Carvone, Piperitone, Pulegone, Diosphenol
  • Dicyclic: Camphor, Fenchone, Thujone
• Camphor


  • SN: Cinnamomum camphora
  • Const: Camphor - Natural: Dextro, Synthetic: Racemic
  • Anti-pruritic, rubefacient, anti-infective
  • Camphor + menthol = eutectic mixture = lower m.p.
• Spearmint


  • SN: Mentha spicata
  • Const: (-) Carvone
• Caraway


  • SN: Carum carvi
  • Const: (+) Carvone
• Buchu

  • SN: Barosma betulina
  • Const: Diosphenol
  • Use: OTC for menstrual period
• Cedar leaf oil


  • SN: Thuja occidentalis
  • Const: (+) Thujone, (-) Fenchone
  • Use: Vicks Vaporub®
• Phenol volatile oils

  • Thyme oil
  • Clove oil
  • Myrcia oil
  • Creosote
  • Juniper tar
  • Pine tar