Hexanoic acid, 4-methyl- (CAS 1561-11-1) — Sweet Middle Note Fragrance Ingredient
Hexanoic acid, 4-methyl-
CAS 1561-11-1
What Is Hexanoic acid, 4-methyl-?
Hexanoic acid, 4-methyl- is a synthetic fragrance ingredient used to add fruity, cheesy, or waxy notes to perfumes and flavored products. You might encounter it in tropical fruit fragrances or dairy flavorings. This molecule matters because it bridges fruity and dairy accords, allowing perfumers to create complex, unexpected scent transitions.
Safety Profile
GENERALLY SAFEWhat Does Hexanoic acid, 4-methyl- Smell Like?
4-Methylhexanoic acid delivers a paradoxical duality – opening with a burst of overripe pineapple skin and sweaty cheese rind that gradually settles into a warm, waxy honeycomb note. The top has a sharp, almost fermented fruit character that evolves into a creamy mid-section reminiscent of cultured butter. In drydown, it leaves a faint coconut husk impression with a subtle animalic undertow, making it useful for adding depth to tropical compositions.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used sparingly here to enhance the rum-and-coconut accord, adding a lactonic creaminess that bridges the citrus top notes to the woody base.
Provides a fermented fruit effect in this hyper-green composition, mimicking overripe vegetation beneath the galbanum and lily-of-the-valley notes.
2D Molecular Structure
SMILES: CCC(C)CCC(O)=O
Chemistry, Properties & Perfumer Guide
The Chemistry
4-Methylhexanoic acid is a branched-chain fatty acid with the methyl group positioned at the gamma carbon. While theoretically obtainable through fermentation, commercial production typically involves hydrocarbon oxidation or Grignard reactions. The branched structure lowers its melting point compared to straight-chain isomers, contributing to its distinctive waxy-fruity odor profile. The gamma-methyl branching also affects volatility, making it more persistent than linear hexanoic acid derivatives.
Physical & Chemical Properties
| Boiling Point | Not available |
|---|---|
| Density | Not available |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Used as modifier in tropical accords |
| Functional Fragrance | 0.01-0.1% | Up to 0.3% | Adds dairy nuances to cleaning products |
Classic Accords
Tip: Counterbalance the cheesy top notes with clean musks or ionones to prevent unpleasant associations.
Alternatives & Comparisons
Straight-chain version with sharper, more goat-like character. Use when less fruity sweetness is desired.
Alpha-branched isomer with stronger sweaty notes. Better for animalic accords.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted under current IFRA standards.
RIFM Assessment
Considered safe at current use levels based on structural analogs.
Sustainability
As a synthetic material, production avoids agricultural land use but depends on petrochemical feedstocks. Some manufacturers are exploring bio-based routes using modified yeast strains, though these are not yet commercially viable at scale.
Explore Hexanoic acid, 4-methyl-
Browse essential oils and aroma compounds.
Browse on iHerb →Affiliate disclosure: we may earn a small commission at no extra cost to you.
References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID70862692
Physical Properties
| Molecular Weight | 130.187 g/mol🔬 EPA CompTox |
| Density | 0.945 g/cm^3📊 OPERA |
| Boiling Point | 215.493 °C📊 OPERA |
| Melting Point | 6.147 °C📊 OPERA |
| Flash Point | 98.632 °C📊 OPERA |
| Refractive Index | 1.431 Dimensionless📊 OPERA |
| Molar Volume | 139.085 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.263 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 1.662 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -0.075 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.98 Log10 unitless📊 OPERA |
| Water Solubility | 0.03 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.069 mmHg📊 OPERA |
| Viscosity | 3.909 cP📊 OPERA |
| Surface Tension | 29.001 dyn/cm📊 OPERA |
| Thermal Conductivity | 141.544 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 | 36.002 cm^3/mol📊 OPERA |
| Polarizability | 14.272 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.
