N/A (synthetic molecule — formerly manufactured in Europe)
Pyramid
Heart
Transparent, waxy, lily-of-the-valley freshness with a quiet aldehydic glow — like smelling cold petals through a clean windowpane. The the most tenacious muguet molecule developed commercialised, and the first major fragrance chemical to be outright banned by the EU for causing contact dermatitis.
Soft, transparent, waxy-floral — lily-of-the-valley stripped of green sharpness, left with only the cool, dewy petal. Less heavy than hydroxycitronellal, less aggressively green than Lilial, more persistent than either. A faint cyclamen-lilac undertone runs beneath the muguet signature, giving it a sweetness that stops short of gourm and. The aldehydic quality is restrained: present as a luminous glow rather than a metallic edge. On skin, Lyral reads as clean, slightly waxy, almost soapy — the molecule essentially defined the olfactory concept of 'freshly laundered fabric' for fifty years. Compared to its replacement Nympheal, Lyral is warmer and more rounded; compared to Bourgeonal, it is lighter, less assertive, more diffuse.
Evolution over time
Immediately
Immediately
A cool, transparent aldehydic flash — waxy, slightly soapy, with a clean lily-of-the-valley brightness. The cyclamen-lilac undertone is perceptible immediately but does not dominate. Light, diffuse, quietly luminous.
After a few hours
After a few hours
The muguet character deepens and softens. The aldehydic edge recedes, leaving a warm, waxy, almost creamy floral — rounder now, with a faint powdery sweetness. The extraordinary substantivity becomes apparent: the molecule has barely faded while lighter companions have evaporated.
After a few days
After a few days
On fabric, a clean, abstract floral warmth persists for days — waxy, slightly soapy, entirely non-animalic. On skin, a faint aldehydic ghost remains: dry, transparent, almost imperceptible but still recognisably 'clean.' This is the trace that defined what fresh laundry smelled like for two generations.
The Full Story
Lyral — formally 4-(4-hydroxy-4-methylpentyl)-3-cyclohexene-1-carboxaldehyde, INCI name HICC, CAS 31906-04-4 — is a synthetic fragrance ingredient discovered in 1958 and commercially introduced in 1960. It was the dominant muguet (lily-of-the-valley) aldehyde in perfumery for over half a century before being banned by the European Union in 2019. MW 210.31, bp ~319°C (est.), density 0.989–0.997 g/cm³. The commercial product is a 70:30 mixture of two regioisomers: the 4-substituted (major, CAS 31906-04-4) and 3-substituted (minor, CAS 51414-25-6) cyclohexene carboxaldehydes.
Synthesis
Lyral is produced via a Diels-Alder [4+2] cycloaddition: myrcenol (a monoterpenoid alcohol derived from myrcene) reacts with acrolein at 50–130°C without requiring a catalyst, yielding the isomeric mixture directly. Lewis acid catalysts such as zinc chloride can be employed to improve regioselectivity, but the uncatalysed thermal route is the standard industrial method. The simplicity and atom economy of this one-step synthesis contributed to Lyral's commercial dominance — it was cheap, efficient, and scalable.
Olfactory Character and Significance
Lyral's odor threshold is approximately 0.1 ng/L of air — potent by any standard. Its scent profile is soft, waxy, floral-aldehydic: lily-of-the-valley with cyclamen and faint lilac nuances, similar to of hydroxycitronellal but more transparent and with substantially greater tenacity. The substantivity of 400 hours at 100% concentration on blotter made it the least volatile muguet odorant available — a critical advantage in functional perfumery (fabric softeners, detergents) where persistence on textiles matters more than sillage in air. Lyral essentially defined what 'clean laundry' smelled like in the West from the 1970s through the 2010s.
The Ban
Lyral causes contact dermatitis via haptenation: the aldehyde carbonyl binds covalently to lysine residues on skin proteins, forming a neo-antigen that the adaptive immune system attacks. By the early 2000s, patch-test data showed HICC sensitization prevalence of approximately 1.9% among European dermatitis patients — the highest rate among all 26 regulated fragrance allergens. The SCCS concluded in its 2012 opinion that HICC should not be used in cosmetic products. Commission Regulation (EU) 2017/1410 added HICC to Annex II (prohibited substances) of the Cosmetics Regulation. From 23 August 2019, products containing HICC could no longer be placed on the EU market; by 23 August 2021, remaining stock had to be withdrawn from shelves. The ban forced reformulation of thousands of products worldwide.
This note in Première Peau. Nuit Elastique. Sample all seven extraits in the Discovery Set.
Did You Know?
Did you know?
Lyral was included in the European Baseline Series for diagnostic patch testing as part of Fragrance Mix II — a panel used by dermatologists to screen for perfume allergy. In SCCS-reviewed clinical data (2012), HICC sensitization prevalence reached 1.9% among consecutively tested dermatitis patients in European clinics, making it the single most potent contact sensitizer among the 26 regulated fragrance allergens. The molecule triggers allergy through haptenation: its aldehyde group binds covalently to lysine residues on skin proteins, creating a neo-antigen the immune system recognises as foreign.
Extraction & Chemistry
Extraction method: Fully synthetic. Produced via uncatalysed Diels-Alder cycloaddition of myrcenol (2-methyl-6-methylene-2,7-octadien-1-ol) and acrolein (propenal) at 50-130°C. The reaction yields a 70:30 mixture of two regioisomers: the 4-substituted isomer (CAS 31906-04-4, major) and the 3-substituted isomer (CAS 51414-25-6, minor). Both isomers are odoriferous. The intermediate myrcenol is itself derived from myrcene, a monoterpene abundant in essential oils. Lewis acid catalysts (zinc chloride) can improve selectivity, though thermal reaction without catalyst is the standard industrial route. Product form: colourless to pale yellow viscous liquid, density 0.989-0.997 g/cm³, bp ~319°C (estimated at 760 mmHg).
BANNED. Prohibited in EU cosmetic products since 23 August 2019 (newly placed products) / 23 August 2021 (full market withdrawal). Listed in Annex II of Regulation (EC) 1223/2009 via Commission Regulation (EU) 2017/1410. SCCS concluded in 2012 that HICC should not be used in cosmetic products due to high sensitization rates (~1.9% prevalence among consecutively tested dermatitis patients). Most global markets have followed the EU ban or imposed severe restrictions.
Heart-note diffuser and muguet anch or. Lyral occupied a unique niche: no other molecule delivered muguet character with comparable substantivity (400 hours on blotter at 100%). Its odor detecti on threshold — 0.1 ng/L of air — made it potent at vanishingly small dosages. In formulati on, it functioned as a transparent floral modifier, adding waxy lily-of-the-valley radiance to white floral, aquatic, and clean-laundry accords without the heaviness of hydroxycitronellal or the greenness of Lilial. Before its ban, Lyral was a structural element in thousands of commercial fragrances and functional products — particularly fabric softeners and detergents, where its extraordinary tenacity on textiles defined the 'clean laundry' smell of the late twentieth century. It blended smooth with hedione, galaxolide, and linalool in fresh-floral architectures. None perfectly replicate Lyral's specific combinati on of transparency, waxy body, and extreme longevity — the ban left a genuine gap in the perfumer's palette.
