S-2-Butyl 3-methylbutanethioate (CAS 2432-91-9) — Sweet Top to middle Note Fragrance Ingredient
S-2-Butyl 3-methylbutanethioate
CAS 2432-91-9
What Is S-2-Butyl 3-methylbutanethioate?
S-2-Butyl 3-methylbutanethioate is a synthetic fragrance ingredient used in perfumery to add fruity, tropical nuances. It’s found in some modern fragrances aiming for exotic, juicy fruit effects. This compound matters because it offers perfumers a unique sulfurous-fruity character that’s more stable than natural fruit extracts, allowing for longer-lasting tropical accords in fine fragrances and body care products.
Safety Profile
USE WITH AWARENESSWhat Does S-2-Butyl 3-methylbutanethioate Smell Like?
This thioester bursts with an intense, ripe tropical fruit character – imagine overripe passionfruit dripping with juice, crossed with the sulfury punch of durian. The opening is aggressively fruity with a rubbery, almost skunky edge that quickly mellows into a more conventional tropical bouquet. As it dries down, the sulfur notes recede to reveal a surprisingly clean, sweet fruitiness reminiscent of guava and pineapple, with a faintly musky undertone that provides tenacity on skin.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the core tropical fruit note, providing both the initial juicy impact and the lingering fruity dry-down that lasts hours longer than conventional fruit notes.
Adds a provocative sulfurous edge to the solar floral accord, creating an impression of sun-warmed tropical flowers with overripe fruit nearby.
2D Molecular Structure
SMILES: CCC(C)SC(=O)CC(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
S-2-Butyl 3-methylbutanethioate belongs to the thioester class of sulfur-containing compounds, which are prized in perfumery for their potent, often tropical or meaty odors. While not found in nature, it’s synthesized through esterification of 3-methylbutanethiol with 2-butanol. The stereochemistry at the 2-position influences the odor profile, with the S-isomer being preferred for its cleaner fruit character. Thioesters like this are increasingly important as they can provide natural-seeming effects at much lower concentrations than traditional esters.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Odor Threshold | Extremely low (ppb range) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Powerful modifier for tropical accords |
| Body Care | 0.01-0.1% | Up to 0.2% | Use sparingly due to potency |
Classic Accords
Tip: Always pre-dilute to 1% or lower before incorporating into blends due to extreme potency.
Alternatives & Comparisons
Offers similar tropical fruit effects but with more grapefruit-like top notes and less sulfurous character, better for fresh applications.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA standards, but usage should follow good practice guidelines for sulfur compounds.
RIFM Assessment
No specific RIFM assessment found; treat as potent sulfur compound with unknown sensitization potential.
Sustainability
As a synthetic material, this thioester avoids agricultural impacts but requires energy-intensive synthesis. Its extreme potency means very small quantities are needed, reducing overall environmental burden compared to less powerful alternatives. Proper handling is essential to prevent sulfur compound emissions.
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References
- Brenna et al. (2002). Sulfur Compounds in Flavors and Fragrances. Chemical Reviews. DOI:10.1021/cr000664p
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID80862941
Physical Properties
| Molecular Weight | 174.3 g/mol🔬 EPA CompTox |
| Density | 0.983 g/cm^3📊 OPERA |
| Boiling Point | 222.186 °C📊 OPERA |
| Melting Point | 41.017 °C📊 OPERA |
| Flash Point | 83.911 °C📊 OPERA |
| Refractive Index | 1.459 Dimensionless📊 OPERA |
| Molar Volume | 188.939 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.167 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.167 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.167 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.76 Log10 unitless📊 OPERA |
| Water Solubility | 0.001 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.382 mmHg📊 OPERA |
| Viscosity | 1.728 cP📊 OPERA |
| Surface Tension | 29.602 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 17.07 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 4 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 51.689 cm^3/mol📊 OPERA |
| Polarizability | 20.491 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.
