Octanoic acid, octadecyl ester (CAS 18312-31-7) — Woody Base Note Fragrance Ingredient

Woody · Sweet

Octanoic acid, octadecyl ester

CAS 18312-31-7

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

What Is Octanoic acid, octadecyl ester?

Octanoic acid, octadecyl ester is a synthetic compound used in fragrance formulations. It is typically encountered in fine fragrances and personal care products as a subtle modifier or fixative. This ingredient helps balance compositions and extend the longevity of other fragrance notes, making it valuable in creating lasting scent experiences.

Safety Profile

GENERALLY SAFE
Generally safeUse with awarenessProfessional use
Safe in regulated products
Not a known allergen
CAS
18312-31-7
Formula
Mixture
MW
Variable
Odor Family
Woody · Sweet
Layer 1 · Enthusiast

What Does Octanoic acid, octadecyl ester Smell Like?

Octanoic acid, octadecyl ester has a faint, waxy odor with subtle fatty undertones. It acts as a quiet background note, blending seamlessly into compositions without overpowering other ingredients. Its dry-down is smooth and persistent, contributing to the overall longevity of a fragrance. The scent is neutral enough to complement both floral and woody accords without introducing significant character of its own.

Scent Profile
Layer 2

2D Molecular Structure

Octadecyl octanoate

SMILES: CCCCCCCCCCCCCCCCCCOC(=O)CCCCCCC

Chemistry, Properties & Perfumer Guide

The Chemistry

Octanoic acid, octadecyl ester is a synthetic ester formed from octanoic acid and octadecanol. It belongs to the class of fatty acid esters, which are commonly used in fragrance formulations for their mild scents and fixative properties. The compound is typically synthesized through esterification reactions under controlled conditions. Its long carbon chain contributes to its stability and low volatility.

Physical & Chemical Properties

Perfumer Guide

Note Position
Base
Volatility
Low (hours to days)
Blending
Good
ApplicationTypical %RangeNotes
Fine Fragrance1-3%Up to 5%Fixative and modifier
Personal Care0.5-2%Up to 3%Subtle base note

Classic Accords

Tip: Use as a subtle fixative to enhance longevity without altering the main accord.

Alternatives & Comparisons

1
Octyl octanoate CAS 2306-88-9

A shorter-chain alternative with similar properties but slightly higher volatility.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

No IFRA restrictions apply to this ingredient.

RIFM Assessment

No specific RIFM assessment found for this ester.

Sustainability

As a synthetic compound, octanoic acid, octadecyl ester is produced through controlled chemical processes with consistent quality. Its environmental impact is relatively low due to efficient synthesis methods and minimal waste generation. Being petroleum-derived, its sustainability depends on the source of raw materials and manufacturing practices.

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References

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

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    Physicochemical Properties

    DTXSID: DTXSID5051816

    Physical Properties

    Molecular Weight 396.7 g/mol🔬 EPA CompTox
    Density 0.83 g/cm^3📊 OPERA
    Boiling Point 424.536 °C📊 OPERA
    Melting Point 41.873 °C📊 OPERA
    Flash Point 216.354 °C📊 OPERA
    Refractive Index 1.451 Dimensionless📊 OPERA
    Molar Volume 461.193 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 10.725 Log10 unitless📊 OPERA
    LogD (pH 5.5) 10.725 Log10 unitless📊 OPERA
    LogD (pH 7.4) 10.725 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 11.71 Log10 unitless📊 OPERA
    Water Solubility 0 mol/L📊 OPERA
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 0 mmHg📊 OPERA
    Viscosity 14.726 cP📊 OPERA
    Surface Tension 30.727 dyn/cm📊 OPERA
    Thermal Conductivity 155.228 mW/(m*K)📊 OPERA

    Molecular Descriptors

    Topological Polar Surface Area 26.3 Ų💻 Computed
    H-Bond Donors 0 count💻 Computed
    H-Bond Acceptors 2 count💻 Computed
    Rotatable Bonds 23 count💻 Computed
    Aromatic Rings 0 count💻 Computed
    Molar Refractivity 124.278 cm^3/mol📊 OPERA
    Polarizability 49.268 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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