Pinene structure elucidation

Pinene structure elucidation

1. USES

2. PINENE STRUCTURE ELUCIDATION Pinene (C 10 H 16 ) is a bicyclic monoterpene chemical compound . There are two structural isomers of pinene found in nature: α-pinene and β-pinene . occurring as major components of the essential oil of pine trees and used as a chemical raw material.

3. Structure of pinene Pinene exist in more than 400 kinds of natural plants, the content of alpha-pinene in turpentine about 60%~70%, beta- pinene content of 20%~30%. 2,6,6-Trimethylbicyclo[3.1.1]hept-2-ene

4. Unsaturation test : Confirm presence of a double bond Presence of bicyclic ring system: The parent hydrocarbon of alpha pinene has molecular formula C10H16 which correspond to the molecular formula of bicyclic compounds(CnH2n-2).

5. Treatment with ethanol and sulphuric acid Alpha terpineol is known compound in literature Confirm the presence of six member ring. Presence of one double bond. Presence of hydroxyl group, gives the idea that this carbon holding hydroxyl is involved in formation of bicyclic ring. Three possibilities: Defined by Bredt’s rule. May have another 3 or 4 membered ring.

6. Presence of –CHMe 2 :It is not in six member ring, It must be in other ring. Conclusion: Formation of Pinene Glycol : indicate double bond is hydroxylated. Formation of Pinonic acid: indicate pinene glycol has six membered ring whose double bond is oxidized. Formation of cis- norpinic acid : Indicate the formed structure has two –COOH group. Confirm the presence of cyclo butane ring.

7. Synthesis of pinene α-Pinene and β-pinene are both produced from geranyl pyrophosphate , via cyclisation of linaloyl pyrophosphate followed by loss of a proton from the carbocation equivalent.