Compounds · Ketones · Terpenoid pathway
Camphor
Also known as 2-Bornanone · Long não — an analysis may use any of these names
Dry, sharp, woody, dusty. Heavy and closed; it does not open out like cineole.
- CAS
- 76-22-2
- Formula
- C10H16O
- Molar mass
- 152.23
- Odour threshold
- 500 ppbin water
- Boiling point
- ≈ 204 °C at atmospheric pressure
The two axes are 37 points apart. Volatility tells you whether the compound leaves a surface early or late; the threshold tells you how much of it the nose needs before it notices. When the two sit this far apart, they explain things the percentages on an analysis cannot explain on their own.
About the CAS number and optical isomers
The CAS number above is the racemic form. Natural camphor from the camphor tree is mainly the (+) form, while camphor synthesised from turpentine is usually a mixture. Routine gas chromatography cannot tell the two forms apart.
Must be declared on the label
This compound was added by Regulation (EU) 2023/1545 to the list of allergens that must be declared individually on cosmetic labels in the European Union. Name to use on the label: CAMPHOR.
The declaration threshold is 0.001% in leave-on products and 0.01% in rinse-off products. This is an EU requirement — see the regulations page for why it matters beyond the EU. This is not legal advice.
Where it comes from
Biosynthetic pathway: Terpenoid pathway — plants build them from identical five-carbon blocks.
About the threshold figure
High. Camphor sounds strong because it sublimes continuously, not because its threshold is low.
Published thresholds differ by several orders of magnitude, because of differences in measuring method, sample purity and panel. The figure here is an order of magnitude for relative comparison, not a measurement. We give it only for compounds where the literature broadly agrees — 52 of the 106 compounds in the library. The rest are left blank rather than guessed.
Why it sits where it does
A bicyclic ketone with a compact structure, so it is fairly stable and boils at around 204 degrees. It sublimes at room temperature, which is rare.
Where else you meet it
Camphor tree, rosemary, galangal, and anti-moth products.