1-Decen-4-yne (CAS 24948-66-1) — Green Top Note Fragrance Ingredient

Green · Citrus

1-Decen-4-yne

CAS 24948-66-1

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

What Is 1-Decen-4-yne?

1-Decen-4-yne is a synthetic fragrance ingredient used to add green, metallic nuances to modern perfumes. You’ll encounter it in avant-garde fragrances and certain household cleaners. While rare, it matters because it provides a sharp, diffusive quality that helps lift other notes, especially in fresh, aquatic, or futuristic compositions.

Safety Profile

USE WITH AWARENESS
Generally safeUse with awarenessProfessional use
Limited safety data – use at low concentrations
Potential skin sensitizer – patch test required
CAS
24948-66-1
Formula
Mixture
MW
Variable
Odor Family
Green · Citrus
Layer 1 · Enthusiast

What Does 1-Decen-4-yne Smell Like?

1-Decen-4-yne delivers a piercing green character reminiscent of crushed stems with an underlying metallic twang like freshly unrolled aluminum foil. The initial burst is intensely sharp, evolving into a cleaner, more ethereal quality over time. In drydown, it leaves behind a whisper of cucumber-like freshness, making it useful for modern aquatic accords.

Scent Profile
Layer 2

2D Molecular Structure

1-Decen-4-yne

SMILES: CCCCCC#CCC=C

Chemistry, Properties & Perfumer Guide

The Chemistry

1-Decen-4-yne is an unsaturated aliphatic hydrocarbon with both a double and triple bond. This unique structure creates high reactivity and distinctive odor properties. While not found in nature, it can be synthesized through controlled acetylene chemistry or as a byproduct of certain petrochemical processes. The molecule’s linear shape contributes to its excellent diffusion.

Physical & Chemical Properties

Perfumer Guide

Note Position
Top
Volatility
Very High (5-30 min)
Blending
Moderate
ApplicationTypical %RangeNotes
Fine Fragrance0.1-0.5%Up to 1%Used sparingly for lift
Functional Products0.01-0.1%Up to 0.3%Freshness booster

Classic Accords

Tip: Use in trace amounts to prevent overwhelming compositions with its metallic sharpness.

Alternatives & Comparisons

1
2,6-Nonadienal CAS 557-48-2

For similar green effects but with more cucumber-like character and better substantivity.

2
Violet leaf absolute CAS 8024-08-6

Natural alternative providing green notes with less metallic harshness.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

Not currently restricted by IFRA. Monitor for future amendments due to structural alerts.

GHS Classification

H315 Skin irritation H319 Eye irritation

RIFM Assessment

No RIFM assessment available. Treat as potential sensitizer until data exists.

Sustainability

As a synthetic petrochemical derivative, 1-Decen-4-yne has higher environmental impact than natural alternatives. However, its extreme potency means very small quantities are needed. Future green chemistry routes may improve sustainability.

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References

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

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    Physicochemical Properties

    DTXSID: DTXSID70401909

    Physical Properties

    Molecular Weight 136.238 g/mol🔬 EPA CompTox
    Density 0.783 g/cm^3📊 OPERA
    Boiling Point 167.812 °C📊 OPERA
    Melting Point -87.649 °C📊 OPERA
    Flash Point 44.57 °C📊 OPERA
    Refractive Index 1.449 Dimensionless📊 OPERA
    Molar Volume 172.002 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 4.431 Log10 unitless📊 OPERA
    LogD (pH 5.5) 4.431 Log10 unitless📊 OPERA
    LogD (pH 7.4) 4.431 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 3.73 Log10 unitless📊 OPERA
    Water Solubility 0.001 mol/L📊 OPERA
    Henry's Law Constant 0.041 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 2.749 mmHg📊 OPERA
    Viscosity 0.742 cP📊 OPERA
    Surface Tension 26.241 dyn/cm📊 OPERA
    Thermal Conductivity 133.505 mW/(m*K)📊 OPERA

    Molecular Descriptors

    Topological Polar Surface Area 0 Ų💻 Computed
    H-Bond Donors 0 count💻 Computed
    H-Bond Acceptors 0 count💻 Computed
    Rotatable Bonds 4 count💻 Computed
    Aromatic Rings 0 count💻 Computed
    Molar Refractivity 46.108 cm^3/mol📊 OPERA
    Polarizability 18.279 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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