In short
Isocyclocitral is a cyclic aldehyde with a powerful, sharp green odour. It is used in small amounts to give a crushed-leaf, slightly earthy freshness to green and citrus compositions.
What Isocyclocitral smells like
Isocyclocitral is a powerful, diffusive green with an earthy, damp-leaf character. One reference describes a foliage-green, weedy, dry odour sometimes called a flower-shop smell; an IFF-attributed description gives green (leaves, stems), earthy, humid, hot, with a lemon tint. Other suppliers list green-leafy, green-stems, earthy-wet and sharp. Whether it is citrusy is disputed: some suppliers name a lemony note, while Fraterworks states that it has no citrus character at all.
- Leading note
- Leafy, earthy green
- Clear facets
- Green stems
- Supporting facets
- Damp earth, herbal
- Faint facets
- Lemon
- Character
- Sharp, earthy, humid, diffusive
What makes Isocyclocitral distinctive
The flower shop: green stems and leaves in a humid, earthy room. Triplal is the tart, citrus-peel green; isocyclocitral is the rooted, damp-foliage one.
Where the descriptions disagree: Several suppliers describe a lemony note; Fraterworks says it has no citrus character at all. The commercial material is a mixture of isomers, which may explain the difference.
How Isocyclocitral is used
Used for natural green-foliage effects; one supplier notes it is useful in fougère bouquets and in hyacinth and sweet-pea accords.
Typical role: modifier (used in small amounts to change the character of a blend).
How Isocyclocitral differs from similar materials
- Triplal
- Triplal is the tarter, more citrus-peel green with a metallic edge; isocyclocitral is earthier, more humid and stem-like.
Each difference compares the published descriptions of the two materials. Smell varies with grade, supplier and dilution; compare them side by side on blotters before substituting one for another.
Formulation considerations
Potent; use from dilution so the green does not turn harsh.
Identity and classification
- Type
- Aroma chemical
- Origin
- Synthetic
- Odour family
- Green / Citrus
- Note position
- Top note
- Physical form at room temperature
- Liquid
- Also known as
- 2,4,6-Trimethylcyclohex-3-ene-1-carbaldehyde
- CAS number
- 1335-66-6
- Composition
- A mixture of 2 isomers, which PubChem records as one substance
The CAS number was checked on 19 October 2026 against PubChem compound 16204527, which records it as a mixture of 2 isomers; no single formula or molecular weight is given for a mixture.
Safety and compliance
The IFRA Standards Library lists a Standard covering Isocyclocitral:
- "Isocyclocitral" — Restriction, 49th Amendment, published 2020-01
Limits differ by product category and are set out in the Standard itself; this page does not reproduce them. The list above reflects the library as read on 19 October 2026.
Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. It has a harmonised EU classification (Regulation (EC) No 1272/2008, Annex VI): H317 may cause an allergic skin reaction. Companies notifying the ECHA C&L Inventory classify it (1,713 reports): H317 may cause an allergic skin reaction (99.8% of reports); H319 causes serious eye irritation (99.8% of reports); H412 harmful to aquatic life with long lasting effects (99.8% of reports); H315 causes skin irritation (78.3% of reports). 3 of the reports find it does not meet the hazard criteria. A skin sensitiser classification concerns handling the neat material and the dose in a finished product; the IFRA Standards, where they apply, set the limits. 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
-
Triplal
Aroma chemical · Green / Citrus — green, leafy, sharp, fresh
-
Galbanum Oil
Essential oil · Green / Resinous — green, sharp, bitter, resinous
-
cis-3-Hexenol
Aroma chemical · Green / Fruity — green, cut grass, leafy, fresh
-
Bergamot Oil (Expressed)
Essential oil · Citrus / Aromatic — citrus, zesty, floral, tea-like
Used in formulas and accords
Not currently used in any published formula.
The Formula & Accord Library lists Isocyclocitral here as soon as a published formula, accord or base uses it.
Further reading
Questions about Isocyclocitral
Is Isocyclocitral natural or synthetic?
Isocyclocitral is synthetic — it is made by chemical synthesis.
What is the CAS number of Isocyclocitral?
1335-66-6. It was checked against PubChem on 19 October 2026.
Is Isocyclocitral covered by an IFRA Standard?
Yes. The IFRA Standards Library lists a Standard covering it: "Isocyclocitral" — Restriction, 49th Amendment. The limits depend on the product category; read the Standard itself before formulating.
Sources
- PubChem — compound 16204527, checked 19 October 2026.
- PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
- IFRA — Standards Library, read 19 October 2026.
- The Good Scents Company — isocyclocitral — odour database.
- Fraterworks — isocyclocitral — distributor's description.
- Parchem — isocyclocitral — distributor's description.
- ChemicalBook — isocyclocitral (CAS 1335-66-6) — odour database.
- 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.