Volatile oil and its properties

What is the volatile oil ?

  A volatile oil are the odorous constituents of various plant parts which evaporates on exposure to air at normal temperature. They are also called essential oil because they represents the essences or odoriferous constituents of the plants. They are mono and sesquiterpenes in nature and obtained from the sap and tissues of certain plants.

   Chemically volatile oils are composed of hydrocarbon or oxygenated derivatives of hydrocarbon. 

         The odor and taste of volatile oil mainly determined by the oxygenated derivatives. They may also contain hydrogenated or dehydrogenated derivatives of the hydrocarbon . All the volatile oils are of vegetable origin & are secreted in oil cells in secretion ducts or cavities or in glandular hairs.

 

 Properties of Volatiles oil :

1.   Volatile oils are colourless liquid, particularly when they are fresh. But on long standing they may oxidize, thus darkening in colour.
2.  They possess characteristic odor.
3.   They have high refractive index and most of them are optically active.
4.   They are immiscible with water but freely soluble in organic solvents such as ether , chloroform,  alcohol etc. This solubility is due to the oxygenated constituents in the volatile oil.
5.   When shaken with sufficient amount of water the odory principle of the oil is partly dissolved.