Hexanoic acid (CAS 142-62-1) — Musky Base Note Fragrance Ingredient
Hexanoic acid
CAS 142-62-1
What Is Hexanoic acid?
Hexanoic acid, also known as caproic acid, is a fatty acid found naturally in animal fats and oils. Consumers encounter it in dairy products like goat cheese and coconut oil. This ingredient matters in perfumery for its sharp, cheesy, and slightly rancid odor profile that adds animalic depth to fragrances when used in trace amounts.
Safety Profile
USE WITH AWARENESSWhat Does Hexanoic acid Smell Like?
Hexanoic acid delivers an intensely pungent, sweaty-cheese aroma with sharp acidic undertones. Upon first application, it assaults the nose with a visceral, almost barnyard-like intensity that gradually softens into a warm, fatty character reminiscent of aged dairy. The dry-down reveals a lingering animalic musk that blends surprisingly well with woody and leather accords, though it remains distinctly ‘dirty’ throughout its evolution. Used above 0.1%, it can overpower a composition, but at micro-doses it provides essential realism to animalic and lactonic fragrances.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to create the controversial animalic backbone that contrasts with the fragrance’s spicy-caramel heart, giving an impression of wild, untamed nature.
Hexanoic acid contributes to the famously divisive ‘unwashed skin’ effect that makes this musk composition so polarizing yet compelling.
2D Molecular Structure
SMILES: CCCCCC(O)=O
Chemistry, Properties & Perfumer Guide
The Chemistry
Hexanoic acid is a straight-chain six-carbon fatty acid (C6:0) belonging to the carboxylic acid family. While it occurs naturally in palm kernel oil (2-3%) and coconut oil (0.5-1%), most commercial production comes from oxidation of hexanol or fractional distillation of mixed fatty acids. The molecule lacks chirality but shows strong hydrogen bonding capacity due to its carboxyl group. Industrial synthesis typically involves air oxidation of hexanal or hydrolysis of hexyl esters.
Physical & Chemical Properties
| Boiling Point | 205 °C |
|---|---|
| Density | 0.927 g/cm³ |
| Vapor Pressure | 0.15 mmHg at 25°C |
| Solubility | 1.1 g/100 mL in water |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.01-0.1% | Up to 0.3% | Used for animalic effects |
| Functional Fragrance | 0.001-0.01% | Trace | Masking agent |
Classic Accords
Tip: Always pre-dilute to 1% or lower before incorporating into blends to avoid overwhelming other notes.
Alternatives & Comparisons
Less aggressive with similar fatty character; better for subtle dairy effects without the cheesy punch.
More diffusive with a sweaty-foot character; useful when seeking more body odor realism.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions. Listed as safe for use in all categories without limitations.
GHS Classification
RIFM Assessment
RIFM assessment confirms safe use at current industry levels with no sensitization concerns.
Sustainability
Most hexanoic acid is synthesized from petrochemical feedstocks, though some is derived from renewable palm kernel fatty acids. The synthetic route has lower environmental impact than agricultural extraction. As a short-chain fatty acid, it readily biodegrades and poses minimal ecological risk.
Explore Hexanoic acid
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. Book reference
- PubChem Compound Summary for Hexanoic acid PubChem
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID7021607
Physical Properties
| Molecular Weight | 116.16 g/mol🔬 EPA CompTox |
| Density | 0.926 g/cm^3🔬 EPA CTX |
| Boiling Point | 203.538 °C🔬 EPA CTX |
| Melting Point | -3.155 °C🔬 EPA CTX |
| Flash Point | 105.799 °C🔬 EPA CTX |
| Refractive Index | 1.428 Dimensionless📊 OPERA |
| Molar Volume | 122.202 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.908 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 1.072 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -0.746 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.9 Log10 unitless📊 OPERA |
| Water Solubility | 0.087 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0.096 mmHg🔬 EPA CTX |
| Viscosity | 3.36 cP📊 OPERA |
| Surface Tension | 30.069 dyn/cm📊 OPERA |
| Thermal Conductivity | 145.819 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 37.3 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 4 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 31.411 cm^3/mol📊 OPERA |
| Polarizability | 12.452 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.
