N/A — found in many essential oils (rose, citronella, neroli)
Appearance
colorless to pale yellow clear oily liquid
Odor Strength
Low
Producing Countries
China, Europe, India
Pyramid
Heart
The quiet hum beneath linden blossom. Farnesol smells like standing under a Tilia tree in late June — waxy, green-white, transparent, barely there but structurally everywhere.
Soft green-floral, waxy, near-transparent. Drier and quieter than linalool, less insistent than geraniol, more vegetal than nerolidol (its structural isomer, which reads woodier and more balsamic). Think linden blossom without the honeyed sweetness — just the pale, waxy-green exhale of petals warming in afternoon sun. A muguet undertone, faintly metallic, like lily-of-the-valley stems crushed between fingers.
Stable linden warmth, the waxy green facet softens into a creamy, almost lactonic floral base note
After a few days
After a few days
Persistent clean-floral trace, dry and papery, like pressed flowers in an old book — the 222 g/mol molecular weight ensures tenacity well beyond lighter terpene alcohols
The Full Story
Farnesol (CAS 4602-84-0, C₁₅H₂₆O, MW 222.37) is an acyclic sesquiterpene alcohol — fifteen carbons, three isoprene units, one hydroxyl group. It boils at 263°C at atmospheric pressure. Its molecular weight places it squarely between the volatile monoterpene alcohols (linalool at 154, geraniol at 154) and the heavier fixatives. This middle ground defines its perfumery behaviour: persistent enough to anchor, light enough not to smother.
The odour is soft, green-floral, faintly waxy. Where linalool projects and geraniol insists, farnesol recedes — a structural presence rather than an olfactory event. It reads as linden blossom (tilleul), lily of the valley (muguet), and unripe pear skin. Transparent rather than rich. The (E,E)-isomer (CAS 106-28-5) is the most commercially significant of its four geometric isomers, though in practice the isomers are olfactively near-identical and sold as mixtures at ≥96% purity.
It occurs naturally in Rosa damascena oil (1–4%), neroli, ylang-ylang, palmarosa, citronella, and linden blossom — the molecule largely responsible for the characteristic tilleul quality. It was first isolated from the flowers of Vachellia farnesiana (the Farnese acacia), a plant cultivated in Rome’s Farnese Gardens from Dominican seed that germinated in 1611. The molecule inherited the family name.
Farnesol is also a key intermediate in the mevalonate biosynthetic pathway — produced by dephosphorylation of farnesyl pyrophosphate, the branch-point precursor to cholesterol, squalene, and all higher terpenoids. This biochemical ubiquity explains its presence in so many essential oils. In Candida albicans, it functions as a quorum-sensing molecule, inhibiting the yeast-to-hypha transition that drives biofilm formation. Beyond perfumery, it is a declared EU allergen under Regulation 1223/2009 Annex III, requiring INCI labelling above 0.001% in leave-on products and 0.01% in rinse-off products.
In 2001, Hornby et al. identified farnesol as the first quorum-sensing molecule ever discovered in a eukaryotic organism. Candida albicans secretes farnesol to prevent its own cells from switching to invasive hyphal growth when population density is high — at 300 micromolar concentration, biofilm formation is completely inhibited. The molecule named after a Renaissance cardinal's garden turned out to be a fungal language.
Extraction & Chemistry
Extraction method: Not typically extracted as an isolate from natural sources. Farnesol occurs at 1-4% in Rosa damascena essential oil and at varying levels in neroli, ylang-ylang, palmarosa, citronella, and linden blossom oils. Commercial farnesol is predominantly synthetic, produced via acid-catalysed isomerisation of nerolidol or through controlled linear prenylation of geraniol. The (E,E)-isomer (CAS 106-28-5) dominates commercial mixtures. Biosynthetically, it arises from dephosphorylation of farnesyl pyrophosphate (FPP), the central C15 intermediate in the mevalonate pathway. Minimum commercial purity: 96% sum of isomers (all four geometric forms — E,E / Z,E / E,Z / Z,Z — are olfactively near-identical).
Molecular Formula
C15H26O
CAS Number
4602-84-0
Botanical Name
N/A — found in many essential oils (rose, citronella, neroli)
Heart-to-base modifier and floral harmoniser. Farnesol anchors delicate white-flower accords without adding weight or colour — it functions as structural scaffolding rather than a signature note. Its 400-hour substantivity (TGSC data at 100%) makes it an effective fixative for fleeting top-note florals. It blends muguet, tilleul, and rose accords, bridging green and floral qualities in a composition. Its low odour strength means it works below the threshold of conscious detection in most formulas, but its removal collapses the architecture of compositions that depend on it. Nerolidol (CAS 7212-44-4), its structural isomer, delivers a woodier, more balsamic effect by comparison. Synthetic farnesol can be obtained by isomerisation of nerolidol.
