5,9-Undecadienal, 2,6,10-trimethyl- (CAS 54082-68-7) — Green Top to middle Note Fragrance Ingredient

ByThe Good Scents
Green · Citrus

5,9-Undecadienal, 2,6,10-trimethyl-

CAS 54082-68-7

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

What Is 5,9-Undecadienal, 2,6,10-trimethyl-?

5,9-Undecadienal, 2,6,10-trimethyl- is a synthetic aldehyde used in perfumery to create fresh, marine, and ozonic effects. It’s found in modern aquatic fragrances and cleaning products. This ingredient matters because it can mimic the crispness of sea air without relying on natural sources, offering sustainability advantages.

Safety Profile

USE WITH AWARENESS
Generally safeUse with awarenessProfessional use
⚠ Potential sensitizer – use below 0.1%
⚠ IFRA restricted – check latest guidelines
CAS
54082-68-7
Formula
Mixture
MW
Variable
Odor Family
Green · Citrus
Layer 1 · Enthusiast

What Does 5,9-Undecadienal, 2,6,10-trimethyl- Smell Like?

5,9-Undecadienal opens with a burst of metallic freshness, like aluminum foil kissed by sea spray. As it evolves, it reveals a cucumber-like watery heart with subtle floral undertones. The dry-down is clean and slightly woody, reminiscent of sun-bleached driftwood. Its tenacity is moderate, making it excellent for creating transparent aquatic effects.

Scent Profile

In Famous Fragrances

Fragrance associations may not reflect actual formulations.

Cool Water(Davidoff, 1988)

Used to enhance the marine freshness, contributing to the iconic ‘blue’ aquatic character that defined 90s perfumery.

Layer 2

2D Molecular Structure

2,6,10-Trimethyl-5,9-undecadienal (mixture of all stereo forms)

SMILES: CC(CCC=C(C)CCC=C(C)C)C=O

Chemistry, Properties & Perfumer Guide

The Chemistry

5,9-Undecadienal is a branched-chain unsaturated aldehyde. Its structure features two double bonds at positions 5 and 9, contributing to its reactivity and odor characteristics. Synthesis typically involves aldol condensation followed by selective hydrogenation. The trimethyl branching increases volatility while maintaining tenacity.

Physical & Chemical Properties

Boiling PointNot publicly available
DensityNot publicly available

Perfumer Guide

Note Position
Top to middle
Volatility
Medium (2-4 hours)
Blending
Good with citrus and woody notes
ApplicationTypical %RangeNotes
Fine Fragrance0.01-0.1%Up to 0.2%For aquatic freshness
Functional Fragrance0.005-0.05%Up to 0.1%In detergents for clean effect

Classic Accords

Tip: Use with citrus top notes to enhance freshness and prevent metallic harshness.

Alternatives & Comparisons

1
Melonal CAS 106-72-9

For stronger cucumber-melon effects when less marine character is desired.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

IFRA restricted due to sensitization potential. Check Amendment 49 for current limits.

EU Allergen Declaration

Not listed as EU allergen.

GHS Classification

H315 Skin irritation H319 Eye irritation

RIFM Assessment

RIFM reviewed with recommended use limits based on sensitization data.

Sustainability

Synthetic production allows consistent quality without marine ecosystem impact. Biodegradability studies suggest moderate environmental persistence.

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References

  1. IFRA Standards Library Amendment 49 IFRA 49

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

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Ingredient Data Sheet

CAS 54082-68-7

Physical Properties

Molecular Weight208.34 g/mol🔬 PubChem
LogP (Octanol-Water)4.4🔬 PubChem
Boiling Point249 °C🔬 EPA CompTox
Vapor Pressure0.0501 mmHg @ 25°C📊 OPERA
Flash Point134.7 °C🔬 EPA CompTox
Involatility Index0.0037💻 Calculated
log Kp (skin permeability)-0.847💻 Calculated
SMILESCC(CCC=C(C)CCC=C(C)C)C=O🔬 PubChem

Volatility & Performance

Fragrance NoteHeart💻 Calculated
Volatility ClassVery slow💻 Calculated
Persistence Score2.9 / 5💻 Calculated

Odor & Flavor

Primary Descriptorscitrusgreen• leffingwell
Functional Groupsaldehydealkene💻 RDKit
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: DTXSID70904728

Physical Properties

Molecular Weight 208.345 g/mol🔬 EPA CompTox
Density 0.847 g/cm^3📊 OPERA
Boiling Point 267.22 °C📊 OPERA
Melting Point 13.518 °C📊 OPERA
Flash Point 114.511 °C📊 OPERA
Refractive Index 1.46 Dimensionless📊 OPERA
Molar Volume 244.157 cm^3/mol📊 OPERA

Partition & Solubility

LogP (Octanol-Water) 4.733 Log10 unitless📊 OPERA
LogD (pH 5.5) 4.733 Log10 unitless📊 OPERA
LogD (pH 7.4) 4.733 Log10 unitless📊 OPERA
LogKoa (Octanol-Air) 6.9 Log10 unitless📊 OPERA
Water Solubility 0 mol/L📊 OPERA
Henry's Law Constant 0 atm-m3/mole📊 OPERA

Transport Properties

Vapor Pressure 0.019 mmHg📊 OPERA
Viscosity 2.936 cP📊 OPERA
Surface Tension 26.502 dyn/cm📊 OPERA
Thermal Conductivity 134.811 mW/(m*K)📊 OPERA

Molecular Descriptors

Topological Polar Surface Area 17.07 Ų💻 Computed
H-Bond Donors 0 count💻 Computed
H-Bond Acceptors 1 count💻 Computed
Rotatable Bonds 7 count💻 Computed
Aromatic Rings 0 count💻 Computed
Molar Refractivity 66.856 cm^3/mol📊 OPERA
Polarizability 26.504 Å^3📊 OPERA

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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