PCOG-Volatile oils

• Hydrocarbon Volatile Oil

  • Limonene - monocyclic terpenes
  • p-Cymene – monocyclic monoterpene : coriander, thyme, cinnamon, myristica
  • Pinene - dicyclic monoterpene : conifer oils, lemon, anise, eucalyptus, thyme, fennel coriander, orange flower and myristica oils
  • Sabinene - dicyclic monoterpene : thujone class; cardamom and lemon oils
  • Acyclic monoterpenes - rare : Myrcene from lemon and myristica oils
  • Cadinene - sesquiterpene hydrocarbon in juniper tar
  • β-Caryophyllene - sesquiterpene with unusual chemical structure; wormwood, peppermint, cinnamon and clove oils
• Turpentine oil

  • Spirts of Turpentine
  • Distilled - oleoresin from Pinus palustris, Pinaceae
  • Largest volume essential oil in commerce
  • Colorless liquid with a characteristic odor and taste  stronger and more disagreeable as the oil ages or is exposed to air.
  • Uses- essential oil and pharmaceutic industry
  •  Constituent/s: (65) a -pinene, (30) b- binene and (5) other terpenes
• Rectified Turpentine oil

  1. distillation from aq sodium hydroxide
  2. Use: Expectorant

  Terpin hydrate or terpinol

  1. nitric acid on rectified turpentine oil in the presence of alcohol.
  2. Cis-p-menthane-1,8-diol hydrate
  3. Use: stimulant to mucous membranes (expectorant) elixir
  4. Dose: 85mg
• II. Alcohol Volatile Oils

  (1) Acyclic,(2) Monocyclic and (3) Dicyclic Alcohol

  • Most important alcohol volatile oils: geraniol, linalool, citronellol
  • Important monocyclic alcohol menthol (from peppermint), α-terpineol
  • Borneol – dicyclic terpene alcohol from Camphor
  • Zingiberol – sesquiterpene alcohol
• Peppermint oil

  • Use/s

  Flavorant (Pharmaceutic aid, confectionary, toothpaste, mouthwash

  and chewing gum)

  Carminative

  Stimulant Counter irritant

  • Synthetic alcohol: Menthol or menthan-3-ol

  from Japanese peppermint by refrigeration (-22O C) during

  which the menthol crystallizes

  Use/s: topical anti-pruritic, counterirritant, antiseptic, stimulant
• Volatile Oils (Terpenes)


  Essential oils/ethereal oils, odorous principles in plants obtained from different parts
• Volatile oils


  • Easily evaporate when exposed to air
  • Obtained from specialized secretory structures in plants
• Specialized secretory structures for volatile oils

  • Glandular hairs: Lamiaceae
  • Modified parenchymal cells: Piperaceae
  • Oil tubes/vittae: Apiaceae
  • Lysigenous/Schizogenous: Rutaaceae and Pinaceae
• Eleoptene


  Hydrocarbon portion, liquid
• Stearoptene


  Oxidized hydrocarbon portion, solid
• Properties of volatile oils

  • Characteristic odor
  • High refractive index
  • Optically active
  • Immiscible with water
  • Sufficiently soluble to impart odor to water
  • Soluble in ether, alcohol (most organic solvents)
• Volatile oils can contain almost any type of organic compounds (HC, alcohols, ketones, aldehydes, ethers, oxides, esters, etc.)
• Only few volatile oils possess a single component (high percentage)
• Volatile oils commonly contain over 200 components
• Absence of one component may change the aroma
• Fixed oils


  Distilled - natural sources, glyceryl esters of fatty acids, permanent grease spot on paper, saponification, oxidize and resinify (light and air)
• Volatile oils


  Esters of fatty acids, permanent grease spot on paper, saponification, rancidify (air)
• Water Distillation


  1. Crude turpentine oleoresin (plant exudate, rainwater, wood chips, pine needles, and others) is introduced into the distilling chamber

  2. Heat until a volatile matter (oil and water) is condensed in the condensing chamber

  3. Turpentine oil is collected and consists of terpenes
• Water and Steam Distillation

  1. Grinding: Dried material is ground and then covered with a layer of water

  2. Generation of steam: Steam is generated elsewhere and piped into the container holding the macerated material

  3. Separation of layers: the oily layer is separated from the aqueous layer
• Direct Steam Distillation


  1. Crop is cut and placed directly into a METAL distilling tank on a truck bed

  2. Truck is driven to a distilling shed where steam lines are attached to the bottom of the distilling tank

  3. Steam is forced through the fresh material and carries the oil droplets through a vapor pipe attached at the top of the tank to the condensing chamber
• Enzymatic hydrolysis


  1. Gaultherin (glycoside) – [H: gautherase] → methyl salicylate (aglycone) + glucose and xylose

  2. Sinigrin (glycooside) – [H: myrosin] → mustard oil
• Plant expression


  1. Ecuelle method - Puncturing the oil glands by rolling the fruit over a trough lined with sharp projections

  2. Pressing: removes the oil from the glands and a fine spray of water washes the oil from the mashed peel while the juice is extracted through a center tube that cores the fruit

  3. Separation: oil-water emulsion is separated by centrifugation
• Enfleurage


  1. An odorless, bland fixed oil or fat is spread in a thin layer of glass plates

  2. Flower petal are placed on the fat for a few hours

  3. Old petals are removed and a new layer of petals is introduced

  4. After the fat has absorbed as much fragrance as possible, oil is removed by extraction with alcohol
• Extraction


  1. Use of solvent system: petroleum ether or benzene

  2. Extracted oil has a more natural odor that is unmatched by distilled oils
• Destructive Distillation


  1. Sample is heated w/o access of air: decomposition takes place → volatile compounds are driven off

  2. Resultant mass: charcoal

  3. Condensed volatile matter separates into 2 layers: Aqueous layer and Tarry layer
• Pneumatic Method


  1. Current or warm air is made to pass through the flowers

  2. Subsequent air loaded with suspended v.o. particles is routed through a fine spray of molten fat in a closed chamber wherein the volatile oil gets absorbed promptly
• Maceration Method


  1. Fresh flower petals: gently and carefully heated in molten fat (lard, tallow, ixed oil) → stirred frequently until complete exhaustion

  2. Flowers are strained and squeezed

  3. Exuded fat is returned to the main bulk of the fat until a desired concentration is achieved

  4. V.o. containing fat is allowed to cool and recovered by 3 successive extractions with absolute alcohol
• General and Medicinal and Commercial Use of Volatile Oils

  • Insect repellants
  • Insect attractants - cross-fertilization of flowers
  • Spices and condiments (anise, clove, nutmeg)
  • Flavoring agents
  • Carminative (eucalyptus oil, wintergreen oil)
  • Perfumery and cosmetics
  • Aromatherapy
• Chemistry of Volatile Oils

  • Mixtures of compounds of diverse types
  • Separation of compounds in various ways: Low temperature, Fractional distillation, Fractional crystallization, Different forms of chromatography, Removal by chemical action
• Terpenes


  Most v.o. consist of terpenes, natural products which structures may be divided into isoprene units (C5H8) that arises from the acetate via mevalonic acid, During formation of terpenes: isoprene units are linked in a head-to-tail fashion, Monoterpenes (C10H16): 2 isoprene units, Sesquiterpenes (15H24): 3 isoprene units, Diterpenes (C20H32): 4 isoprene units, Triterpenes (C30H48): 6 isoprene units
• Phenylpropanoid


  Contains C6 phenyl ring with an attached C3 propane side chain, present in methyl salicyalte and vanillin
• Various constituents of v.o. are responsible for the characteristic odor, flavor, and therapeutic properties
• Stereochemistry - determines the type of olfactory response evoked by the compound: Geometric isomers, Enantiomers (optically active isomers, +/-)
• During formation of terpenes


  Isoprene units are linked in a head-to-tail fashion
• Monoterpenes


  2 isoprene units (most common)
• Sesquiterpenes


  3 isoprene units
• Diterpenes


  4 isoprene units
• Triterpenes


  6 isoprene units
• Phenylpropanoid

  Contains C6 phenyl ring with an attached C3 propane side chain
• Phenylpropanoids


  • Methyl salicylate
  • Vanillin