Isocyclocitral (CAS 1335-66-6) — Citrus Top to Middle Note Fragrance Ingredient

ByThe Good Scents
Citrus · Green

Isocyclocitral

CAS 1335-66-6

Origin
synthetic
Note
Top to Middle
IFRA
Use with awareness
Data as of: Apr 2026

What Is Isocyclocitral?

Isocyclocitral is a synthetic fragrance ingredient primarily used by professional perfumers. While not commonly encountered in consumer products, it may appear in niche fragrances. This molecule is valued for its unique aromatic properties that contribute to complex scent compositions.

Safety Profile

USE WITH AWARENESS
Generally safeUse with awarenessProfessional use
✓ Approved for use in fragrances
⚠ Limited safety data available
CAS
1335-66-6
Formula
Mixture
MW
Variable
Odor Family
Citrus · Green
Layer 1 · Enthusiast

What Does Isocyclocitral Smell Like?

Isocyclocitral presents a complex aromatic profile with citrusy, herbal, and slightly woody undertones. The top note bursts with a sharp, green-citrus character reminiscent of crushed lemon leaves. As it evolves, the heart reveals a more nuanced herbal quality, like dried sage or thyme. The dry-down carries faint woody-resinous traces, though the molecule’s volatility means it primarily functions as a top-to-mid note. Its unique profile adds brightness and naturalistic complexity to fragrance compositions.

Scent Profile
Layer 2

2D Molecular Structure

Isocyclocitral

SMILES: CC1CC(=CC(C1C=O)C)C.CC1C=C(CC(C1C)C=O)C

Chemistry, Properties & Perfumer Guide

The Chemistry

Isocyclocitral belongs to the class of cyclic terpene aldehydes, structurally related to citral but with distinct aromatic properties. As a synthetic material, it’s produced through specialized organic synthesis routes, typically involving cyclization and oxidation steps of appropriate terpene precursors. Its molecular structure gives it unique stability and odor characteristics compared to linear citrus aldehydes.

Physical & Chemical Properties

Perfumer Guide

Note Position
Top to Middle
Volatility
Medium (1-3 hours)
Blending
Good
ApplicationTypical %RangeNotes
Fine Fragrance0.1-0.5%Up to 1%Used as accent note
Functional Fragrance0.05-0.2%Up to 0.5%For freshness effects

Classic Accords

Tip: Use sparingly to add naturalistic citrus-herbal complexity without overpowering.

Alternatives & Comparisons

1
Citral CAS 5392-40-5

For stronger lemon-citrus character, though less stable and more prone to oxidation.

2
Dihydrocyclocitral CAS 432-25-7

Offers similar profile with greater stability and milder odor impact.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

General reference only. Consult current IFRA Standards Library before formulating.

IFRA Status

No specific IFRA restrictions currently apply to isocyclocitral.

RIFM Assessment

Limited safety assessment data available from RIFM.

Sustainability

As a synthetic material, isocyclocitral’s environmental impact depends on production methods. Green chemistry approaches are increasingly used in its synthesis to minimize waste and energy use. Being produced in controlled environments eliminates concerns about overharvesting that affect some natural ingredients.

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References

    Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.

    Report a data error

    Perfumer’s Notes

    MW: 304.5

    Ingredient Data Sheet

    CAS 1335-66-6

    Physical Properties

    Molecular Weight304.5 g/mol🔬 PubChem
    SMILESCC1CC(=CC(C1C=O)C)C.CC1C=C(CC(C1C)C=O)C🔬 PubChem

    Odor & Flavor

    Functional Groupsaldehydealkene💻 RDKit
    “Although there is a marked difference between the odor of the title material and that”📖 Arctander

    Flavor Notes (Arctander)

    “It is interesting that the title material is less Apple-like than the n-Valerate (previous monograph), but apparently the two materials have found only little use in flavor compositions.”📖 Arctander

    Regulatory Status

    IFRA ListedYes — see IFRA Standards for category limits⚖️ IFRA 51
    Data Sources & Attribution
    Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.

    Physicochemical Properties

    DTXSID: DTXSID8044541

    Physical Properties

    Molecular Weight 304.5 g/mol🔬 PubChem

    Molecular Descriptors

    Topological Polar Surface Area 34.14 Ų💻 Computed
    H-Bond Donors 0 count💻 Computed
    H-Bond Acceptors 2 count💻 Computed
    Rotatable Bonds 2 count💻 Computed
    Molar Refractivity 92.51 cm^3/mol💻 Computed

    Data Sources:

    🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.

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