3.isolation and separation of terenoids

isolation of terpenoids by physical and chemical method

1. Isolation and separation of Terpenoids Prepared by Dr. N.GOPINATHAN ASSISTANT PROFESSOR DEPARTMENT OF PHARMACEUTICAL CHEMISTRY FACULTY OF PHARMACY SRI RAMACHANDRA UNIVERSITY CHENNAI-116 TAMILNADU INDIA

2. Essential oil contain a number of terpenoids belonging to mono and sesquiterpenoid group. Isolation of individual terpenoid can be achieved by chemical as well as physical method

3. Chemical method

4. Certain chemical methods have been applied for the separation of terpenoids . In 1877, tilden discovered that whenever terpenoid hydrocarbon are treated with nitrosyl chloride in chloroform [ T ilden’s reagent]. Crystalline adducts having sharp melting point are obtained The adducts were separated and decomposed into their corresponding hydrocarbons.

5. Terpenoid - alcohol It is separated by their reaction with Phthalic anhydride to form diesters when the primary alcohol react readily, secondary alcohol less readily and tertiary do not react. The diesters are extracted with NaHCO3 and then decomposed by alkali to the parent terpenoid alcohol

6. Terpenoid aldehydes and ketones were seperated by reaction with common carbonyl reagent such asNaHCO3, 2,4 dinitro penyl hydrazine, phenyl hydrazine reagent.

7. Physical method Fractional distillation method The various terpenoids present in essential oil are separated by fractional distillation method. The terpenoid hydrocarbon distill over first followed by oxygenated derivative. Distillation of the residue under reduced pressure yield sesquiterpenoids and these are separated by fractional distillation.

8. Fractional distillation is to be carried out under reduced pressure in the presence of an inert gas. These conditions are essential because many terpenes are sensitive to heat and atmospheric oxygen.

9. Chromatography In adsorption chromatography, the essential oil is made to flow through a particular adsorbent Different types of terpenoid are adsorbed at different places on the adsorbent to form different chromatogram

10. Then various chromatograms are eluted by different solvent system to get different elute. Alumina and silica gel are used as adsorbent. Vapor phase partition , counter current and gas chromatography have been used.

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