FRUITS, VEGETABLES AND NUTS / earthy · nutty · woody
Acorn
Category
FRUITS, VEGETABLES AND NUTS
Subcategory
earthy · nutty · woody
Origin
Volatility
Base Note
Botanical
Quercus (genus)
Appearance
pale yellow clear liquid (acorn accord)
Odor Strength
Medium
Producing Countries
Europe, North America
Pyramid
Base
Dry oak leaves gathered into a fist. A woody-herbal molecule — 1-ethynylcyclohexyl acetate — that smells of hay bales, immortelle, and the tannin-dusted floor of an autumn forest. Not the nut itself, but the air around the tree.
Dry, herbal, woody. The first impressi on is of oak leaves gathered from the ground after the first frost — papery, faintly tann in-bitter, with a hay-sweet undertone. An immortelle-like honeyed warmth threads through the middle, but without the curry-spice quality of actual Helichrysum italicum. Compared to oakmoss, acorn acetate is cleaner and less damp. Compared to coumar in, it is less powdery, more vegetal. The overall character is autumnal and specific: forest flo or, not flower shop.
Evolution over time
Immediately
Immediately
Sharp herbal-woody attack. Dry oak leaves, a flash of green bitterness. The aldehydic bite of crumpled plant matter.
After a few hours
After a few hours
Hay-sweet warmth develops. The immortelle facet surfaces — honeyed, slightly curry-like but restrained. Woody-herbal body, dry and clean.
After a few days
After a few days
Faint, dry, papery warmth. A tannin-like woody trace persists, closer to dried herbs than to fresh wood. Clean and autumnal.
The Full Story
Acorn acetate (1-ethynylcyclohexyl acetate, CAS 5240-32-4) is a synthetic arom a chemical — a tertiary propargylic ester with molecular formul a C₁₀H₁₄O₂, molecular weight 166.22 g/mol. It is the primary molecule used in perfumery to carries the scent of acorns and oak forest flo or. No natural essential oil or absolute of acorns exists for perfumery use. The molecule itself is colourless, liquid at room temperature, with a boiling point of 201–202°C and moderate vapour pressure (0.303 mmHg at 25°C).
TGSC describes the odour as ‘natural acorn, dry oak leaves, hay, woody, immortelle, herbal.’ The profile is particular: drier and more tannic thanvetiver, less smoky than guaiac wood, with a pronounced hay-like sweetness similar to of immortelle. The herbal dimension sits between dried thyme and crushed walnut shell. There is nothing fruity about it. The scent reads as autumnal, papery, and faintly bitter — closer to dried leaves than to the nut itself.
Synthesis
Industrial production follows a two-step sequence: acetylene is added to cyclohexanone under basic conditions (typically KOH in liquid ammonia or DMSO) to yield 1-ethynylcyclohexanol (CAS 78-27-3), which is then acetylated with acetic anhydride or acetyl chloride to give the final ester. The chemistry is straightforward — a Reppe-type ethynylation followed by standard esterification. The starting materials are inexpensive bulk chemicals, making acorn acetate an affordable ingredient.
Relationship to Real Acorns
Actual acorns (Quercus spp.) do not conta in 1-ethynylcyclohexyl acetate. GC-MS analys is of roasted Quercus humboldtii acorns (Warsi to et al., 2019) identified furfural, 5-methylfurfural, furfuryl alcohol, and 3-hydroxy-2-butanone as the dominant volatiles — compounds associated with caramel, gra in, and roasted-nut arom as. The connecti on between the molecule and its trade name is suggestive rather than chemical: acorn acetate smells like the ide a of acorns in an autumn woodl and, not like the nut’s actual headspace.
Acorn acetate contains no chemical found in actual acorns. GC-MS analys is of roasted Quercus humboldtii acorns identified furfural, 5-methylfurfural, and furfuryl alcohol as dominant volatiles — none of which are structurally related to 1-ethynylcyclohexyl acetate. The trade name is a perfumer’s metaph or: the molecule carries the atmosphere of an oak forest in autumn, not the chemistry of the nut itself.
Extraction & Chemistry
Extraction method: Fully synthetic. No natural acorn essential oil or absolute exists for perfumery use. Industrial synthesis proceeds in two steps: (1) ethynylation of cyclohexanone with acetylene under basic conditions (KOH, liquid ammonia or DMSO) to yield 1-ethynylcyclohexanol (CAS 78-27-3); (2) acetylation of the tertiary alcohol with acetic anhydride to give 1-ethynylcyclohexyl acetate. Starting materials are inexpensive bulk chemicals. The product is a colourless, clear liquid.
Molecular Formula
C₁₀H₁₄O₂ (acorn acetate, MW 166.22)
CAS Number
5240-32-4 (acorn acetate — the synthetic molecule used to recreate acorn notes)
Botanical Name
Quercus (genus)
IFRA Status
Permitted with restriction. IFRA recommends a maximum of 10% in the fragrance concentrate. RIFM safety assessment published 2019 (Food and Chemical Toxicology, PubMed 31356913).
Synonyms
OAK NUT
Physical Properties
Odor Strength
Medium
Lasting Power
72 hours at 100%
Appearance
pale yellow clear liquid (acorn accord)
Boiling Point
201.00 to 202.00 °C. @ 760.00 mm Hg (est)
Flash Point
179.00 °F. TCC ( 81.67 °C. )
Specific Gravity
1.00100 to 1.00900 @ 25.00 °C.
Refractive Index
1.46300 to 1.46800 @ 20.00 °C.
In Perfumery
Acorn acetate (1-ethynylcyclohexyl acetate) functions as a heart-to-base modifier in woody, herbal, and chypre-adjacent compositions. Its primary contribution is a dry, natural-smelling oakleaf-hay character that grounds green and woody accords without adding smoke or resin. At low doses (0.5–2%), it introduces an autumnal, herbal dryness — useful in fougere bases, hay accords, and masculine woody ambers. At higher concentrations, it becomes a recognisable signature: the dry-oak character that Christopher Sheldrake reportedly deployed in compositions built around forest and wood themes. The molecule pairs effectively with oakmoss (or its synthetic replacements like evernyl), coumarin, vetiver, and patchouli. It can also bridge herbal top notes — thyme, clary sage — into woody-ambery bases. IFRA recommends a maximum of 10% in the fragrance concentrate. Substantivity is moderate: TGSC reports 72 hours at 100% concentration, placing it firmly in the heart-to-base range. Odor strength is medium.
