Compounds · Other compounds · Heat (Maillard reaction and pyrolysis)
2-Furfurylthiol
Also known as Coffee mercaptan · 2-Furylmethanethiol — an analysis may use any of these names
Roasted coffee in its purest form. At high concentration it becomes the smell of burnt rubber.
- CAS
- 98-02-2
- Formula
- C5H6OS
- Molar mass
- 114.17
- Odour threshold
- 0.010 ppbin water
- Boiling point
- ≈ 155 °C at atmospheric pressure
For this compound the two axes sit close together. Volatility tells you whether it leaves a surface early or late; the threshold tells you how much of it the nose needs before it notices.
Where it comes from
Biosynthetic pathway: Heat (Maillard reaction and pyrolysis) — fire breaks large molecules into ones you can smell.
About the threshold figure
Very low threshold. It makes up a few parts in ten thousand of roasted coffee but dominates the whole impression.
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 furan ring attached to a sulphur-containing thiol group. A small, fast-evaporating molecule, but its extremely low detection threshold lets it dominate everything else.
Where else you meet it
Roasted coffee is the main source. Also found in grilled meat and popcorn.