Volatile oils

1. Volatile oils Silpa M Assistant professor Dept. of Pharmacognosy Yenepoya pharmacy college & research centre

2. Contents • Definition • General properties • Chemical nature • Classification • Preparation / isolation • Testes of volatile oil • Uses

3. Definition • The odorous, volatile principles of plant and animal sources are known as volatile oils. They are liquid, volatile oils will evaporate or volatize when exposure at an ordinary temperature and so they are called ethereal oils. They are also called as essential oils as they are essences or concentrated constituents of the plants.

4. General properties of volatileoils • They are soluble in alcohol, ether and other lipid solvents and practically insoluble in water. • They are usually lighter thanwater. • They possesscharacteristic odoursand they have high refractiveindex

5. 4. Most of them are opticallyactive. 5. They are secreted in special structure such as duct, cell, schizogenousor lysigenousgland,trichomes. 6. They are commonly found in thespecies of Labiatate, Rutaceae, Piperaceae, Zingeberaceae, Umbellifereae, Myrtaceae , andLauraceae. 7. They are present in entire plant or in any part of theplant.

6. CHEMICALNATURE: • Chemically , they are derived from terpenesand their oxygenated compounds. They are made up of isoprene units ( C5H8) and are usually mono-, sesqui-, and diterpeneswith empirical formulae as C10 H16, C15 H24, and C20H32respectively.

7. CLASSIFICATION • Volatile oil classifying mainly three types, on the basis of ; • Number of isoprene units • Functional group • Cyclic structure

8. Classification on the basis of isoprene units

9. Classification on the basis of functional group

11. Classification on the basis of Cyclic structure

12. Preparation / isolation of volatileoils • The principal methods used in the preparation of volatile oils from plants dependon: • Distillation in water orsteam. • Mechanicalmethods. • Enfleurage(extractionofoils used in perfumery). • Ecuellemethod

13. Extraction withsolvents. • Enzymatichydrolysis(for glycosidicvolatile oils e.g. mustardoil). • Supercritical fluidextraction

14. 1. Distillationmethod This is the most widely used method for the extraction of volatileoil PROCEDURE–Theplantmaterialis macerated and thens teamdistilled,when the essential oils go into distillate from which they areextracted bypureorganicvolatile

16. However , the method should be used with a great care , sincesome essential oils are decomposed during distillation and some are hydrolyzed to none or less fragrant compounds

17. 2. Mechanicalmethods • A) Enfleuragemethod • B) Ecullemethod

18. Enfleuragemethod • It is also known as cold fatextraction • Used for theextractionofdelicateperfumes from Flowerpetals

19. Method- • Thefreshflower petals aremechanically spread on a layer of fatty material, ( A glass plate is covered with a thin coating of especially prepared and odourlessfat) allowed to imbibe and the exhausted petals are replaced by freshmaterial.

21. The process is continued till the fatty layer is saturated with volatile principles, which are then extracted with lipid solvent like ethyl alcohol. • The extract having ethyl alcohol and essential oils is distilled under reduced pressure to remove thesolvent.

22. Advantages– • In case of distillation method , volatile oil may undergoes hydrolysis, polymerization or resinificationor delicate oils becomes lost in large volumes of water or where the flowers continue to produce fragrance after the harvest effleurage is usuallypracticed

23. Ecuellemethod ( Expressionmethod) • It is also known as expressionmethod • Usedfor theextractionofcitrusoilsfrom citrus fruits.

24. Method– • Here oil cells inrind are ruptured mechanically using pointed projections by twisting the raw materialoverthem in Clockwisedirection either mechanically or manually. • The oil is then separated from the from the juice by centrifugation • Theother halfoftheoilisgenerallynot extracted and such residue is used for the isolation of inferior quality of oil by distillation.

25. Eg: citrus, lemon and grass oils are extracted by thismethod

26. 3. Extraction with solvents • Here they are using volatile solvents to extract the volatile oil. i.ePetroleum ether, benzene • Method– • Fresh flowers are transferred into specially constructed extractors at room temperature and carefully treated with purified solvent , usually petroleumether.

27. The solvent penetrates the flowers and dissolves the natural perfume together with some waxes and other albuminousand coloringmatter • This solution is pumped into an evaporator and concentrated at low temperature. After complete evaporation of solvent the flower oil isobtained.

28. Application– • This method is used in perfume industryfor the production of volatile oils using lipids solvents like petroleum ether orbenzene • Advantages- • It isquick • Quality assured and economicalmethod

29. Thedecompositionofvolatileoilis les s as compared to hydro distillationmethod • Thesolventdistilledoffmaybereusedfor extraction

30. 4. Enzymaticextraction • Here , the volatile oil is normally found in plants substances in the form of odourlessglycosidalcombination. However , the odoriferous compounds are liberated free only byhydrolysis. • Volatile oil of bitter almond (Benzaldehyde)

31. Test for volatile oils

32. Uses of volatile oil • Therapeutically (Oil ofEucalyptus) • Flavouring(Oil ofLemon) • Perfumery (Oil ofRose) • Starting materials to synthesize other compounds (Oil ofTurpentine) • Anti-septic – due to high phenols (Oil of Thyme). Also as a preservative (oils interfere with bacterialrespiration) • Anti-spasmodic (Ginger, Lemonbalm, Rosemary, Peppermint, Chamomile, Fennel, Caraway) • Aromatherapy

33. Questions LONG ESSAYS (10M) • Define Volatile oils. Classify volatile oils based on the functional group and isoprene units. SHORT ESSAY (5M) • Discuss the different extraction techniques to extract volatile oils SHORT ANSWERS (2M) • Importance of volatile oils • Write the pharmaceutical application of volatile oil

34. THANK YOU