Pinene structure elucidation

3. USES

4. PINENE STRUCTURE ELUCIDATION
Pinene (C10H16) 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.

5. 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

6. Unsaturation test : Confirm presence of a double bond
N O
C l
N O C l
B r 2
B r
B r
A l p h a P i n e n e
A l p h a P i n e n e n i t r o s y l c h l o r i d e A l p h a P i n e n e d i b r o m i d e
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).

7. Alpha Pinene
Ethanol/Sulphuric acid
OH
Alpha Terpineol
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.

8. Presence of –CHMe2: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.

9. 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.