In short
alpha-Irone is the ketone family responsible for the scent of orris. It is used to recreate or extend orris butter.
What alpha-Irone smells like
Alpha-irone is the orris molecule: rich, floral and powdery, with orris and violet character. A supplier lists sweet, orris, woody, raspberry and powdery, and describes it as extremely diffusive, giving volume and tenacity. A distributor notes that its odour is very similar to the ionones, which are much cheaper and often used in its place, but that it diffuses better. A glossary describes irones as smoother and more angular than the ionones, with a suede-like grain. It occurs in orris root.
- Leading note
- Powdery orris
- Clear facets
- Violet
- Supporting facets
- Woody, suede-like
- Faint facets
- Raspberry
- Character
- Powdery, cool, smooth, diffusive
What makes alpha-Irone distinctive
Cool, smooth orris: more rooty, suede-like and diffusive than the ionones, which are sweeter and fruitier.
How alpha-Irone is used
Used in orris and violet compositions for volume, diffusion and tenacity, and in orris reconstructions.
Typical role: modifier (used in small amounts to change the character of a blend).
How alpha-Irone differs from similar materials
- alpha-Ionone
- A distributor calls them very similar, with cheaper ionones often used instead; alpha-irone is more diffusive, smoother and more orris-like. (compared directly by a cited source)
- Orris Butter (Orris Concrete)
- Orris butter owes its violet-powdery character to irones; the butter adds a fatty, earthy, carrot-like root body.
An asterisk marks a difference that a cited source states directly. The others compare the published descriptions of each material. Smell varies with grade, supplier and dilution; compare them side by side on blotters before substituting one for another.
Formulation considerations
Costly compared with ionones; quality varies with isomer composition.
Identity and classification
- Type
- Aroma chemical
- Origin
- Occurs in nature
- Odour family
- Powdery / Woody
- Note position
- Heart to base note
- Physical form at room temperature
- Liquid
- CAS number
- 79-69-6
- Molecular formula
- C14H22O
- Molecular weight
- 206.32 g/mol
- IUPAC name
- (E)-4-(2,5,6,6-tetramethylcyclohex-2-en-1-yl)but-3-en-2-one
The CAS number, formula and molecular weight are taken from PubChem compound 5371002, whose own record lists this CAS number; checked 19 October 2026.
Safety and compliance
Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. Companies notifying the ECHA C&L Inventory classify it (1,686 reports): H412 harmful to aquatic life with long lasting effects (17.7% of reports). 1,323 of the reports find it does not meet the hazard criteria. Unless it is harmonised, this is the notifiers' own classification, not a binding one.
This page is general information, not a safety assessment or a specification. Confirm identity, composition, IFRA status and allergen content from your supplier's documents for the lot you hold.
Materials it works with
-
Orris Butter (Orris Concrete)
Concrete · Powdery / Woody — powdery, iris, woody, buttery
-
beta-Ionone
Aroma chemical · Powdery / Woody — violet, woody, fruity, raspberry
-
alpha-Isomethyl Ionone
Aroma chemical · Powdery / Floral — powdery, violet, orris, woody
alpha-Irone is also suggested as a partner on the pages for Orris Absolute.
Used in formulas and accords
Used in 37 published formulas
alpha-Irone is an ingredient in 34 perfume formulas and 3 accords in the Formula & Accord Library.
RUŌOD House Originals
Original compositions by RUŌOD House.
Further reading
Questions about alpha-Irone
Is alpha-Irone natural or synthetic?
The molecule occurs in nature. Commercial alpha-Irone may be made by synthesis or obtained from natural sources, so check the supplier's specification if the distinction matters to you.
What is the CAS number of alpha-Irone?
79-69-6. It was checked against PubChem on 19 October 2026.
Which published formulas use alpha-Irone?
alpha-Irone is used in 37 published formulas in the RUŌOD Lab Formula & Accord Library, including Ambrette Halo, Anise Ink and Birch Ghost. Each is listed with a link under "Used in formulas and accords" on this page.
Sources
- PubChem — compound 5371002, checked 19 October 2026.
- PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
- De Hekserij — Irone alpha — distributor's description.
- Parchem — alpha-irone — distributor's description.
- Premiere Peau — Orris root — published perfumery reference.
- Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 20 October 2026. Evidence: more than one published description. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.