Volatile Oils
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Volatile oils, also known as essential oils, are aromatic oily liquids found in many plants. They are highly volatile and evaporate easily at room temperature. Volatile oils are composed of hydrocarbons and oxidized hydrocarbons derived from terpenes. They are found stored in secretory cells, cavities, or channels located in different parts of plants. Volatile oils have various therapeutic uses and are also used in perfumes, cosmetics, and flavorings due to their strong aromas. They are extracted from plants using various techniques including water and steam distillation, solvent extraction, and enfleurage.
Volatile Oils
- 2. Introduction Definition: • The odorous, volatile principle of plant and animal source are known as volatile oil. • As they evaporate when exposed to air at ordinary temperature ,they are also called ethereal oil. • Volatile oils are also called essential oil because they produce essence.
- 3. • Lighter than water • Optically active • High refractive index • Specific rotation • Possess distinct odours • Commonly found in the species Labiatae,Rutaceae,piperaceae,zingiberaceae,umbelliferae,myrtaceae,la uraceae • They are present in entire plant or in any part of the plant • Donot leave stains like fixed oils • Insoluble with water and soluble in organic solvents like ether,alcohol,chlorofrm,ethanoletc • They should be stored in a cool,dry place in tightly stoperred,preferablly full(not half emptied),amber glass container.
- 4. Volatile oils generally composed of two portions: Hydrocarbon – terpene derived from acetate mavelonic acid pathway and are called eleoptenes.(Liquids) Oxidized hydrocarbon derived from shikimic acid phenylpropanoid pathway are called steareoptenes.(solids) Steareoptenes are water soluble but more alcohol soluble. The odour and taste of vol. oils is due to the oxygenated part Note:When eleoptenes and stereoptenes combine, result in vol. oils.
- 5. Glandular hair in Labiatae Modified parenchyma cells in Piperaceae Special tubes or oil tube in pericarp of fruits of umbelliferae Lysogenous and schizogenous cavities in Rutaceae In the conifers ,V.O may occur in all tissues Petals of rose Bark of cinnamon Fruit of coriander Leaves of pepper mint
- 7. Plants 1. Citronella oil, being a volatile oil, is an insect repellent obtained from plants thus preventing the destruction of the flowers and leaves. 2. Insect attractant volatile oils help in the cross fertilization of different species of plants. Humans 1. As a flavoring agent. 2. Used in perfume industries and in cosmetics 3. As starting material for synthesis of other compounds 4. Used as a therapeutic agent
- 8. THERAPEUTIC ACTIVITIES a. As a counter irritant b. Eucalyptus oil administered as an inhalant. c. Improves local circulation d. As carminative,shows anti-spasmodic. e. Thymol is used in mouth washes and gargles f. Local an anesthetic g. Reduce secretion of lungs in cough and asthma. h. Antiseptic,anti bacterial, anti fungal i. Anti helminthes j. Also used in aroma therapy(eg.lavander,rosemary)
- 9. 1. Distillation by water It is applied to plants which are not injured upon boiling.Turpentine oil is obtained by this method. Crude turpentine is introduced into the distillation chamber along with water and subjected to heat below 40 C . A mixture of oil and water is obtained as a distillate which is collected in a Florentine flask.The distillate is separated into two layers oil being withdrawn through the upper outlet of the condenser and water from the lower outlet or vice versa in case of clove as clove oil is heavier than water. 2. Water and steam distillation For substances which are usually injured by direct heat for example clove, cinnamon. Dried drug ground and covered with layer of water. Steam is passes through mixture, steam is generated by another chamber and piped into container having drug.The vapour contain vol oils are introduced in condensing chamber cooled and collected.
- 11. 3. Destructive distillation without air (vaccum) Members of pinacaea are used.Tough materials such as barks,seeds and roots may be comminuted to facilitate extraction. Broken pieces of wood are placed in chamber and heated with water without air in a vaccum.The decomposition of wood occurs and volatile oils generated are collected through the condenser. 4. Ecuelle Method Ecuelle method is used for the extraction of citrus oils where oils cells in rind are ruptured mechanically using pointed projections by twisting raw material over them in clockwise direction either mechanically or manually.
- 12. 5. Enfleurage Enfleurage method is used for extraction of delicate perfumes. In this method, layer of fat is spread over a glass plate and flower petal are placed over fat layer which absorbs v.o .The exchausted petals are replaced by fresh petals.This process continues till the fatty layer is saturated volatile principle which are then extracted with lipid solvent. 6. Solvent extraction It is used in perfume industry and is an expensive method. In this technique parts containing volatile oils are extracted directly by one of the organic solvent as they are crushed and mixed in the solvent and are separated by distillation.eg.oil of rose
- 14. Many volatile oils consist largely of terpenes. Terpenes are defined as natural products whose structure may be divided into isoprene units. These units arise from acetate via mevolonic acid pathway. Isoprenes are 5 carbon compound having 2 unsaturated bonds. (C5H8) They are joined in head to tail fashion. Isoprene is also termed as hemi-terpenes.
- 15. The classification of its chemistry is as follows: n Formula Name 2 C10H16 Monoterpenoids 3 C15H24 Sesquiterpenoid 4 C20H32 Diterpenoid 5 C25H40 Sesterpenoid 6 C30 H48 Triterpenoids 8 C40H64 Tetraterpenoids 8> 40> Polyterpenoids
- 16. It can also be sub classified according to the number of rings present in the structure. 1. Acyclic terpenoid: open structure 2. Mono terpenoid: one ring in structure 3. Bicyclic terpenoid: two rings 4. Tricyclic terpenoid: three rings 5. Tetracyclic terpenoid: four rings
- 17. Hydrocarbon vol oils :cubeb ,terpentine oil Alcoholic vol oils :peppermint ,cardamom, corriander Aldehyde vol oils: cinnamon ,bitter orange peel,sweet orange peel, lemon peel Phenolic vol oils: clove,thyme Ketonic vol oils: camphor,spearmint,caraway,buchu leaves Phenolic ether vol oils :fennel ,anise ,myristica Oxidized vol oils :euclyptus ,chenopodium Ester vol oils :rosemary Miscellaneous vol oil :anethum ,allium