Warm, cedar-smooth, almost subliminal. Iso E Super registers less as a smell than as a presence — a woody haze that wraps the wearer and drifts at the edge of perception, appearing and disappearing as olfactory receptors saturate and reset.
Smooth, cedar-toned, with a dry peppery edge and a warmth that reads as texture rather than scent. Drier and more abstract than sandalwood, less sharp than Virginia cedarwood, warmer and rounder than ambroxan's mineral projection. There is a faint amber sweetness underneath — not gourmand, more like sun-warmed plywood — and a skin-like quality that makes it feel personal. At threshold concentrations, it produces the sensation of standing near something warm and wooden without being able to identify the source.
Evolution over time
Immediately
Immediately
A soft cedar-like warmth, faintly peppery, diffusing outward from the first moments. More felt than smelled — registers as a warm wooden presence rather than a distinct note. Some wearers perceive almost nothing at first application.
After a few hours
After a few hours
The characteristic fade-in-fade-out cycle begins. The woody-amber warmth deepens, gains a smooth, skin-like sweetness. Bystanders often detect a stronger sillage than the wearer, whose receptors periodically saturate. A dry, clean base emerges.
After a few days
After a few days
Exceptional tenacity on fabric — detectable beyond 72 hours. On skin, a faint, warm, abstract woodiness persists. On blotter, substantivity exceeds 170 hours at full concentration. The residual trace is clean, dry, and nearly scentless to the adapted nose.
The Full Story
Iso E Super (CAS 54464-57-2) is a synthetic woody-amber ketone, formally octahydro-tetramethyl-naphthalenyl-ethanone (OTNE). It was first synthesized in 1973 via Diels-Alder cycloaddition of myrcene with 3-methyl-3-penten-2-one, followed by cyclization under phosphoric acid catalysis. The commercial product is not a single molecule but a mixture of isomers: approximately 30-65% beta-isomer, 10-26% alpha-isomer, and 8-20% gamma-isomer. The beta-isomer — the bulk of the mixture — is nearly odorless. The scent attributed to Iso E Super actually comes from a trace component called Arborone (the gamma-isomer), present at only 2-5% of the mixture, whose odor threshold is roughly 100,000 times lower than the beta-isomer's.
This isomeric reality explains the molecule's signature perceptual behavior: it fades in and out of awareness. The olfactory receptors that detect the gamma-isomer saturate rapidly, creating brief anosmia. When they reset, the scent reappears. The wearer loses it; bystanders catch it. The effect is a fragrance that seems to breathe — present, then absent, then present again — without any change in the composition itself.
In formulation, Iso E Super serves as both structural backbone and performance enhancer. At 1-5%, it contributes warmth and roundness. At 10-30%, it becomes the primary architectural element of a composition, functioning as invisible scaffolding. It has high tenacity (172+ hours at full concentration on blotter), excellent material compatibility, and strong diffusion. An estimated 80% of modern fine fragrances contain it.
Commercial variants differ primarily in gamma-isomer content. Standard grades contain roughly 8% gamma-isomer. Enriched versions push this to 15-22%, yielding a more pronounced, smoother woody character with reduced metallic undertones. The purified gamma-isomer alone — while olfactively superior — remains difficult to produce at industrial scale via selective synthesis.
This note in Première Peau. Albâtre Sépia · Doppel Dänçers · Gravitas Capitale · Insuline Safrine · Nuit Elastique · Rose Monotone · Simili Mirage. Sample all seven extraits in the Discovery Set.
The scent everyone attributes to Iso E Super actually comes from a trace impurity. The beta-isomer that constitutes 30-65% of commercial Iso E Super is nearly odorless (threshold ~500 ng/L air). The gamma-isomer, present at only 2-5%, has a threshold of ~5 pg/L — roughly 100,000 times more potent. In 1990, researchers identified this minor component, called Arborone, as the true source of the characteristic woody-amber note. No industrially viable route to pure Arborone has yet been developed.
Extraction & Chemistry
Extraction method: Purely synthetic. No natural source exists. Produced via Diels-Alder cycloaddition of myrcene (a terpene from turpentine or litsea cubeba oil) with 3-methyl-3-penten-2-one (mesityl oxide), followed by intramolecular cyclization catalyzed by phosphoric acid. The reaction yields a mixture of positional isomers — alpha, beta, and gamma — in varying ratios depending on reaction conditions, catalyst loading, and purification steps. Industrial production is large-scale. The commercial product (typically >96% purity across all isomers combined) is a colorless to pale yellow liquid with a specific gravity of 0.960-0.968 at 25 C.
Molecular Formula
C16H26O
CAS Number
54464-57-2
Botanical Name
Synthetic (no botanical source)
IFRA Status
Permitted. IFRA restricts Iso E Super (OTNE) to a maximum of 12.78% in Category 4 (fine fragrance applied to skin). Not classified as an EU fragrance allergen under Annex III of the Cosmetics Regulation. REACH registered.
Synonyms
OTNE · ISO E SUPER · ARBORONE (gamma-isomer) · TIMBERSILK · SYLVAMBER
Physical Properties
Odor Strength
Medium
Lasting Power
172 hours at 100.00%
Appearance
colorless to pale yellow clear liquid
Boiling Point
312.16 °C. @ 760.00 mm Hg (est)
Flash Point
232.00 °F. TCC ( 111.11 °C. )
Specific Gravity
0.96000 to 0.96800 @ 25.00 °C.
Refractive Index
1.49700 to 1.50200 @ 20.00 °C.
In Perfumery
Backbone material, diffusion enhancer, and texture modifier. Iso E Super provides the woody-amber foundation on which a large proportion of contemporary fragrances are built. At low doses (1-5%), it lends warmth and smoothness without identifiable character. At high doses (10-30%), it becomes the dominant structural element — the load-bearing wall of the composition. It functions across every fragrance family. In woody ambers, it is often the primary material by volume. In white florals, it extends sillage and smooths indolic sharpness. In citrus-aromatic compositions, it provides a warm landing in the drydown. Its near-universal compatibility with other aroma chemicals makes it the most-used single ingredient in contemporary use. Iso E Super also acts as a perceptual amplifier: compositions containing it project further and read as more layered than their formulas alone would predict. This is partly chemical (its vapor pressure and diffusion coefficient are well-suited to slow, steady evaporation) and partly perceptual (the fading-in-and-out phenomenon creates an impression of movement and complexity). At Première Peau, Iso E Super contributes woody clarity and spatial diffusion to several compositions. In Doppel Dancers, it gives the iris accord with a clean, modern transparency.
