3-Methylpentanoic acid (CAS 105-43-1) — Musky Base Note Fragrance Ingredient
3-Methylpentanoic acid
CAS 105-43-1
What Is 3-Methylpentanoic acid?
3-Methylpentanoic acid is a synthetic fragrance ingredient used in perfumes and flavorings. It’s typically encountered in fine fragrances and personal care products. This compound adds a unique cheesy, sweaty note that perfumers use to create animalic or leathery accords in small quantities.
Safety Profile
USE WITH AWARENESSWhat Does 3-Methylpentanoic acid Smell Like?
3-Methylpentanoic acid delivers an intensely animalic, cheesy-sweaty aroma at full strength, reminiscent of unwashed human skin or aged cheese rinds. In dilution, it transforms into a warm, leathery note with a fatty undertone. The scent evolves from a sharp, acidic punch to a lingering animalic musk in the dry-down, making it valuable for creating sensual, skin-like accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to amplify the animalic musk core, contributing to the famously carnal, skin-like quality of this controversial masterpiece.
Provides subtle animalic warmth beneath the rich oriental notes, enhancing the perfume’s regal sensuality.
Adds authentic leathery sweat notes to recreate the smell of traditional Russian leather preparation.
Chemistry, Properties & Perfumer Guide
The Chemistry
3-Methylpentanoic acid is a branched-chain fatty acid with the molecular formula C6H12O2. It’s synthesized through oxidation of corresponding alcohols or via Grignard reactions. The branched structure at the 3-position creates steric hindrance that affects its odor profile compared to straight-chain isomers. This synthetic molecule doesn’t occur naturally in significant quantities.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Approx. 195-205°C |
| Density | ~0.92 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.01-0.1% | Up to 0.3% | Used in trace amounts for animalic effects |
| Functional Fragrance | <0.05% | Up to 0.1% | Rarely used due to strong odor |
Classic Accords
Tip: Always pre-dilute to 1% or lower before incorporating into blends due to intense odor.
Alternatives & Comparisons
More pungent cheesy note, useful when stronger projection is needed in animalic accords.
Similar but slightly sweeter, less sweaty profile for softer animalic effects.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific IFRA restrictions. General guidelines for carboxylic acids apply.
GHS Classification
RIFM Assessment
Not currently assessed by RIFM. Considered safe at typical usage levels.
Sustainability
As a synthetic material, 3-methylpentanoic acid has minimal environmental impact in production. Its high potency means very small quantities are needed, reducing overall resource consumption compared to natural animalic materials.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
- Arctander, S. (1969). Perfume and Flavor Chemicals. Allured Publishing.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
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