5,9-Dimethyl-4,8-decadienal (CAS 762-26-5) — Citrus Top Note Fragrance Ingredient

ByThe Good Scents
Citrus · Sweet

5,9-Dimethyl-4,8-decadienal

CAS 762-26-5

Origin
synthetic
Note
Top
IFRA
Generally safe
Data as of: Apr 2026

What Is 5,9-Dimethyl-4,8-decadienal?

5,9-Dimethyl-4,8-decadienal is a synthetic fragrance ingredient used to add fresh, citrusy, and marine nuances to perfumes. It’s commonly found in modern aquatic and fresh fragrances. This aldehyde is valued for its ability to create sparkling top notes that evoke ocean breezes and crisp citrus zest, making it popular in summer fragrances and body care products.

Safety Profile

GENERALLY SAFE
Generally safeUse with awarenessProfessional use
✓ Safe in regulated products
⚠ Check IFRA restrictions
CAS
762-26-5
Formula
Mixture
MW
Variable
Odor Family
Citrus · Sweet
Layer 1 · Enthusiast

What Does 5,9-Dimethyl-4,8-decadienal Smell Like?

5,9-Dimethyl-4,8-decadienal opens with a burst of effervescent citrus, reminiscent of freshly peeled mandarin and grapefruit. The heart reveals a subtle marine character, like sun-warmed seaweed on a rocky shore. As it dries down, a clean, slightly woody undertone emerges, providing lasting freshness. The overall effect is vibrant yet refined, with a modern edge that sets it apart from traditional citrus aldehydes.

Scent Profile

In Famous Fragrances

Fragrance associations may not reflect actual formulations.

Cool Water(Davidoff, 1988)

Used to enhance the aquatic freshness, creating a modern interpretation of ocean air with citrus sparkle.

L'Eau d'Issey(Issey Miyake, 1992)

Adds a crisp, watery citrus note that complements the floral heart, evoking dewdrops on petals.

Layer 2

2D Molecular Structure

5,9-Dimethyl-4,8-decadienal

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

Chemistry, Properties & Perfumer Guide

The Chemistry

5,9-Dimethyl-4,8-decadienal is a branched-chain unsaturated aldehyde. Its synthesis typically involves the oxidation of corresponding alcohols or controlled ozonolysis of appropriate dienes. The molecule’s reactivity is influenced by its conjugated double bond system, which contributes to both its olfactory properties and chemical stability. As a synthetic material, it offers consistent quality and avoids sourcing issues associated with natural alternatives.

Physical & Chemical Properties

Boiling PointN/A
DensityN/A

Perfumer Guide

Note Position
Top
Volatility
Medium (1-2 hours)
Blending
Good
ApplicationTypical %RangeNotes
Fine Fragrance0.5-2%Up to 5%Creates fresh openings
Body Care0.1-0.5%Up to 1%Adds clean character

Classic Accords

Tip: Use alongside other fresh notes to enhance diffusion and longevity.

Alternatives & Comparisons

1
Citral CAS 5392-40-5

For stronger lemon character but less marine nuance.

2
Melonal CAS 106-72-9

When a more pronounced green melon note is desired.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

No specific restrictions under current IFRA standards.

RIFM Assessment

Considered safe for use in fragrances at typical concentrations.

Sustainability

As a synthetic material, 5,9-Dimethyl-4,8-decadienal avoids agricultural impacts but requires energy-intensive production. Its consistent quality reduces batch variability common in natural materials.

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References

  1. Arctander, S. (1969). Perfume and Flavor Chemicals.
  2. IFRA Standards Library Safety guidelines

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

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Ingredient Data Sheet

CAS 762-26-5

Physical Properties

Molecular Weight180.29 g/mol🔬 PubChem
LogP (Octanol-Water)3.5🔬 PubChem
Boiling Point249.4 °C🔬 EPA CompTox
Vapor Pressure0.0167 mmHg @ 25°C📊 OPERA
Flash Point94 °C🔬 EPA CompTox
Involatility Index0.0013💻 Calculated
log Kp (skin permeability)-1.315💻 Calculated
SMILESCC(=CCCC(=CCCC=O)C)C🔬 PubChem

Volatility & Performance

Fragrance NoteHeart💻 Calculated
Volatility ClassVery slow💻 Calculated
Persistence Score3.5 / 5💻 Calculated

Odor & Flavor

Primary Descriptorscitrussweet• leffingwell
Functional Groupsaldehydealkene💻 RDKit

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: DTXSID4052504

Physical Properties

Molecular Weight 180.291 g/mol🔬 EPA CompTox
Density 0.875 g/cm^3🔬 EPA CTX
Boiling Point 249.4 °C🔬 EPA CTX
Melting Point 4.247 °C📊 OPERA
Flash Point 94 °C🔬 EPA CTX
Refractive Index 1.459 Dimensionless📊 OPERA
Molar Volume 210.767 cm^3/mol📊 OPERA

Partition & Solubility

LogP (Octanol-Water) 4.4 Log10 unitless🔬 EPA CTX
LogD (pH 5.5) 4.123 Log10 unitless📊 OPERA
LogD (pH 7.4) 4.123 Log10 unitless📊 OPERA
LogKoa (Octanol-Air) 5.8 Log10 unitless📊 OPERA
Water Solubility 0 mol/L🔬 EPA CTX
Henry's Law Constant 0 atm-m3/mole📊 OPERA

Transport Properties

Vapor Pressure 0.017 mmHg🔬 EPA CTX
Viscosity 2.113 cP📊 OPERA
Surface Tension 28.094 dyn/cm📊 OPERA
Thermal Conductivity 136.824 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 6 count💻 Computed
Aromatic Rings 0 count💻 Computed
Molar Refractivity 57.631 cm^3/mol📊 OPERA
Polarizability 22.847 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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