Compounds · Alcohols · Terpenoid pathway
Terpinen-4-ol
Also known as 4-Carvomenthenol · Terpinenol-4 — an analysis may use any of these names
Earthy, slightly medicinal, dry. Not pleasant on its own, but without it lavender loses its footing.
- CAS
- 562-74-3
- Formula
- C10H18O
- Molar mass
- 154.25
- Odour threshold
- —
- Boiling point
- ≈ 209 °C at atmospheric pressure
Where it comes from
Biosynthetic pathway: Terpenoid pathway — plants build them from identical five-carbon blocks.
Why it sits where it does
A tertiary alcohol with an exposed hydroxyl group, forming strong hydrogen bonds, so it is held back fairly long. It sits clearly in the second half of the band.
Set it beside two compounds with the same formula and the role of the hydroxyl group becomes clear. 1,8-Cineole and α-terpineol are both C₁₀H₁₈O, with the same molar mass of 154.25. Cineole boils at 176 degrees because its oxygen is locked in an ether bridge and cannot donate hydrogen; terpinen-4-ol boils at 209 degrees and α-terpineol at 219 because both have a free hydroxyl. The same atoms, forty-three degrees apart.
Where else you meet it
Tea tree, nutmeg, oregano. It is the main quality marker of tea tree oil.