A molecule is one chemical compound. SmellBook lists furfural because 2 VERIFIED claims name it in the evidence for 3 Atlas entries: Old Book, Library, Brown Sugar.
What it is
These identifiers pin down exactly which compound is meant, so the same molecule can be found in other databases. They say nothing about how it smells.
Checked against PubChem and Wikidata on 2026-10-06 by an automated identifier check. Every name SmellBook uses must resolve to the same single PubChem compound.
Where research reports it
Each report below is a VERIFIED claim, quoted with its scope and the source it rests on. The role says what the claim states about the molecule, in the claim’s own words.
Reported volatile · the claim says “known volatile paper degradation products”
The study detected it. The claim says nothing about its part in the smell.
Headspace analysis of degrading historic paper found acetic acid and furfural, known volatile paper degradation products, and put forward lipid peroxidation products among other compounds of potential interest.
Scope: Paper samples after a 24-hour pre-degradation in the laboratory; the study does not attribute the smell of old books to any single compound.
Reported volatile · the claim says “known volatile paper degradation products”
The study detected it. The claim says nothing about its part in the smell.
Headspace analysis of degrading historic paper found acetic acid and furfural, known volatile paper degradation products, and put forward lipid peroxidation products among other compounds of potential interest.
Scope: Paper samples after a 24-hour pre-degradation in the laboratory; the study does not attribute the smell of old books to any single compound.
Linked to the odour · the claim says “aroma-active compounds”
The study linked it to the smell, as one contributor among several or as a possible one.
Of the 37 aroma-active compounds found in brown sugar, furfural, benzeneacetaldehyde, 2,3-butanedione, β-damascenone, 2-methoxyphenol, dihydro-2-methyl-3(2H)-furanone, 2-furanmethanol and butyrolactone could significantly enhance the sweetness of a sugar solution.
Scope: Non-centrifugal cane sugar; the finding concerns how these compounds raise perceived sweetness in a sugar solution, not their share of the smell of brown sugar.
Any cause and effect beyond the claim's own words. SmellBook does not add that the molecule causes, or is, the smell of an entry; most smells come from many compounds together.
How the pure molecule smells on its own. SmellBook does not describe the odour of single molecules in its own words; a claim may only quote what a study's assessors noted.
How much of it there is, or whether people can smell it at the amounts measured, unless a claim says so.
That it is absent from smells not listed here. A missing entry means no registered claim names it there.
Anything about safety or health.
WHAT THIS MEANS
SmellBook lists a molecule only where a VERIFIED claim names it, in the role and scope that claim states. A molecule reported in a smell's evidence is not the whole smell: most smells come from many compounds together, and the studies measured particular samples, such as one cultivar, an essential oil or a cooked product.