3,4-Hexanedione (CAS 4437-51-8) — Sweet Middle Note Fragrance Ingredient

ByThe Good Scents
Sweet · Balsamic

3,4-Hexanedione

CAS 4437-51-8

Origin
synthetic
Note
Middle
IFRA
Professional use
Data as of: Apr 2026

What Is 3,4-Hexanedione?

3,4-Hexanedione is a synthetic fragrance ingredient primarily used in professional perfumery. It’s not commonly encountered in consumer products but may appear in niche fragrances. This molecule contributes unique caramelic, buttery nuances to compositions.

Safety Profile

PROFESSIONAL USE
Generally safeUse with awarenessProfessional use
⚠ Limited safety data available
⚠ Requires professional handling
CAS
4437-51-8
Formula
Mixture
MW
Variable
Odor Family
Sweet · Balsamic
Layer 1 · Enthusiast

What Does 3,4-Hexanedione Smell Like?

3,4-Hexanedione delivers a potent, diffusive aroma reminiscent of warm butter caramel with toasted sugar undertones. The initial burst carries a slightly metallic edge that quickly mellows into rich dairy notes. As it evolves, it reveals a brown-sugar sweetness with a subtle woody backbone. The dry-down persists with a persistent gourmand character that blends well with vanilla and spice accords.

Scent Profile
Layer 2

2D Molecular Structure

3,4-Hexanedione

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

Chemistry, Properties & Perfumer Guide

The Chemistry

3,4-Hexanedione is a diketone with molecular formula C6H10O2. As a synthetic compound, it’s produced through controlled oxidation reactions of hexane derivatives. The 1,2-diketone structure makes it highly reactive, contributing to its strong odor characteristics. The molecule lacks chirality due to its symmetrical structure.

Physical & Chemical Properties

Perfumer Guide

Note Position
Middle
Volatility
Medium (2-4 hours)
Blending
Moderate
ApplicationTypical %RangeNotes
Fine Fragrance0.1-0.5%Up to 1%Used sparingly for caramelic effects
Flavors0.01-0.1%Trace amountsFor dairy/buttery notes

Classic Accords

Tip: Use in trace amounts to avoid overwhelming compositions with its potent caramel character.

Alternatives & Comparisons

1
Acetylpropionyl CAS 600-14-6

Similar caramelic profile with slightly less intensity and better blending properties.

2
Diacetyl CAS 431-03-8

Stronger butter note but with greater safety concerns and volatility issues.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

Not currently restricted by IFRA standards.

RIFM Assessment

No RIFM assessment currently available for this material.

Sustainability

As a synthetic compound, 3,4-Hexanedione production has minimal environmental impact compared to natural extracts. Its efficient synthesis allows for precise control of purity and reduces waste. However, the petroleum-derived starting materials raise some sustainability concerns.

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References

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

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    Ingredient Data Sheet

    CAS 4437-51-8

    Physical Properties

    Molecular Weight114.14 g/mol🔬 PubChem
    LogP (Octanol-Water)0.5🔬 PubChem
    Boiling Point123 °C🔬 EPA CompTox
    Flash Point32.8 °C🔬 EPA CompTox
    log Kp (skin permeability)-3.041💻 Calculated
    SMILESCCC(=O)C(=O)CC🔬 PubChem

    Volatility & Performance

    Fragrance NoteTop💻 Calculated

    Odor & Flavor

    Primary Descriptorsbutterycaramelnutty• leffingwell
    Functional Groupsketone💻 RDKit
    “Pungent buttery odor, not as diffusive or 66-721 ; 8649;”📖 Arctander
    2,3-Hexanedione has a powerful, creamy, sweet and buttery odor (less than diacetyl) and a buttery cheese taste.📖 Fenaroli

    Regulatory Status

    IOFI ClassificationNature Identical📖 Fenaroli
    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: DTXSID3047681

    Physical Properties

    Molecular Weight 114.144 g/mol🔬 EPA CompTox
    Density 0.943 g/cm^3🔬 EPA CTX
    Boiling Point 128 °C🔬 EPA CTX
    Melting Point -10 °C🔬 EPA CTX
    Flash Point 32.875 °C🔬 EPA CTX
    Refractive Index 1.406 Dimensionless📊 OPERA
    Molar Volume 121.816 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 0.419 Log10 unitless📊 OPERA
    LogD (pH 5.5) 0.419 Log10 unitless📊 OPERA
    LogD (pH 7.4) 0.419 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 3.73 Log10 unitless📊 OPERA
    Water Solubility 0.604 mol/L📊 OPERA
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 5.235 mmHg📊 OPERA
    Viscosity 0.812 cP📊 OPERA
    Surface Tension 29.331 dyn/cm📊 OPERA
    Thermal Conductivity 151.723 mW/(m*K)📊 OPERA

    Molecular Descriptors

    Topological Polar Surface Area 34.14 Ų💻 Computed
    H-Bond Donors 0 count💻 Computed
    H-Bond Acceptors 2 count💻 Computed
    Rotatable Bonds 3 count💻 Computed
    Aromatic Rings 0 count💻 Computed
    Molar Refractivity 29.905 cm^3/mol📊 OPERA
    Polarizability 11.855 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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