What does citronellal mean?
Citronellal is an organic compound — specifically an aldehyde — best known as the principal component of citronella oil, the fragrant extract of certain tropical lemongrass species. It is a colourless to pale-yellow liquid with a strong, pleasant lemon-like odour, and it is prized both by perfumers, who value its fresh, clean scent, and by manufacturers of insect repellents, since mosquitoes find it disagreeable. The name derives from 'citronella', itself a diminutive of 'citron', reflecting its citrusy aroma. Beyond its familiar role in candles, sprays, and lotions, citronellal has industrial significance as a starting material for synthesising other compounds such as menthol. Although essentially a scientific and commercial term rather than part of everyday vocabulary, it neatly illustrates how a single molecule can be responsible for a widely recognised sensory experience — the distinctive smell we associate with summer evenings free of mosquito bites.
nounA colourless, lemon-scented oily liquid aldehyde (C10H18O... actually C9H16CHO, formula C10H16O) found chiefly in citronella oil and used as a fragrance and in insect repellents.
- A colourless, lemon-scented liquid aldehyde (C10H16O) occurring in citronella oil and used in perfumery and insect-repellent preparations.
- Any preparation or product whose active aromatic ingredient is this compound, e.g. a candle or spray (commercial usage).
"The crisp, lemony character of the soap comes from a high concentration of citronellal."
"Citronellal makes up a large fraction of citronella oil distilled from Cymbopogon winterianus."
"Chemists can convert citronellal into menthol through a cyclisation reaction, a route once used industrially."
Rarely pluralised; as an uncountable technical substance it normally appears in the singular. A plural would occur mainly when referring to different stereoisomeric forms or samples.
"The two stereoisomeric citronellals differ noticeably in odour."
That sharp lemony smell that keeps mosquitoes away? That's largely one single molecule: citronellal.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of citronellal
The word citronellal was formed in the late nineteenth century from 'citronella' — the name of the fragrant grass oil from which the compound was first isolated — combined with the '-al' ending characteristic of aldehydes in chemical nomenclature. 'Citronella' is itself a diminutive of 'citron', the fragrant citrus fruit, whose name traces back through French and Italian to Latin 'citrus'. Related words sharing this root include 'citrus', 'citrate', and 'citron' itself.
How citronellal is actually used
A technical term used mainly in chemistry, perfumery, and entomology; rarely encountered outside scientific or commercial contexts. In British English it is typically pronounced with stress on the third syllable, and American pronunciation is similar. The spelling should not be confused with the near-identical 'citronellol', which denotes a different chemical.
Easily confused with citronellal
Citronellal is the aldehyde form of the compound, while citronellol is its corresponding alcohol — a closely related but chemically distinct substance also found in citronella oil.
Citral is an aldehyde mixture obtained from lemongrass oil, whereas citronellal is a different aldehyde obtained primarily from citronella oil.
Citronella refers to the grass plant or its essential oil, of which citronellal is only the principal chemical constituent.