S-1-Methylethyl 3-methylbut-2-enethioate (CAS 34365-79-2) — Sweet Top to middle Note Fragrance Ingredient
S-1-Methylethyl 3-methylbut-2-enethioate
CAS 34365-79-2
What Is S-1-Methylethyl 3-methylbut-2-enethioate?
S-1-Methylethyl 3-methylbut-2-enethioate is a synthetic fragrance compound used in perfumery to create fruity, tropical, and sometimes wine-like nuances. It’s found in niche fragrances and some tropical-themed body care products. This ingredient adds a sophisticated twist to fruity accords, bridging the gap between natural-smelling fruitiness and abstract modern compositions. Its subtle sulfurous character provides depth without overpowering, making it valuable for creating complex, evolving scent profiles.
Safety Profile
USE WITH AWARENESSWhat Does S-1-Methylethyl 3-methylbut-2-enethioate Smell Like?
S-1-Methylethyl 3-methylbut-2-enethioate opens with a burst of tropical fruit – think overripe passionfruit mingled with pineapple skin. The initial impression quickly evolves into something more complex: a wine-like character emerges, reminiscent of Sauvignon Blanc’s tropical notes with a subtle sulfury edge. As it dries down, it reveals a creamy, almost lactonic quality that blends beautifully with florals. The sulfur aspect remains present but refined, adding dimension rather than overt funk. This molecule behaves like nature’s own tropical fruit accord, but with better longevity and projection than natural extracts.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the core tropical fruit accord, providing authentic passionfruit and guava nuances without being cloying. The sulfurous facet adds sophistication to what could otherwise be a simple fruity composition.
Employed in a 2:1 ratio with cis-3-hexenol to create a hyper-realistic tropical garden effect. The molecule’s wine-like character bridges the gap between the fruity top notes and floral heart.
Used at 0.8% to create an abstract ‘synthetic fruit’ effect in this avant-garde composition. The sulfurous aspect is amplified with mercaptans to create a futuristic tropical vibe.
Provides the authentic passionfruit core of this floral-fruity fragrance. Blended with jasmine absolutes to enhance the natural lactonic facets of both materials.
Forms the backbone of the mango-papaya accord, with its sulfurous character adding necessary depth to prevent the tropical fruits from smelling candied or artificial.
2D Molecular Structure
SMILES: CC(C)SC(=O)C=C(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
S-1-Methylethyl 3-methylbut-2-enethioate belongs to the thioester class of sulfur-containing compounds, prized in perfumery for their powerful, often fruity odors. The molecule features a prenyl thioester structure, with the sulfur atom contributing both to odor potency and molecular stability. Industrially, it’s synthesized via esterification of 3-methyl-2-buten-1-thiol with isobutyric acid derivatives. The stereochemistry at the 1-position influences odor characteristics, with the S-isomer being preferred for its cleaner tropical fruit profile compared to the racemic mixture.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | ~210 °C (estimated) |
| Density | ~0.95 g/cm³ (estimated) |
| Solubility | Soluble in alcohol, oils; insoluble in water |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 3% | Tropical fruit accords |
| Body Care | 0.1-0.5% | Up to 1% | Tropical shower gels |
| Candles | 0.3-1% | Up to 2% | Summer fruit themes |
| Functional Products | 0.05-0.2% | Up to 0.5% | Subtle fruit nuances |
Classic Accords
Tip: Use at 0.5-1% in fruity florals to add natural-seeming depth without overwhelming delicate florals.
Alternatives & Comparisons
For more pronounced tropical passionfruit character with less sulfurousness. Better for fresh applications where a cleaner fruit profile is desired.
When a more cooked fruit/meaty sulfur character is needed. Works well in gourmand tropical compositions.
For simpler tropical fruit effects with less wine-like complexity. More cost-effective for mass market applications.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific IFRA restrictions. General sulfur compound guidelines apply.
EU Allergen Declaration
Not listed as an EU allergen.
GHS Classification
RIFM Assessment
RIFM assessment pending. Preliminary data suggests safe use at current industry levels.
Sustainability
As a synthetic material, S-1-Methylethyl 3-methylbut-2-enethioate offers consistent quality without agricultural variability. Production typically uses petrochemical feedstocks, though some manufacturers are exploring bio-based routes using fermentation-derived intermediates. The molecule’s potency means small quantities achieve significant effects, reducing overall environmental load compared to natural extracts requiring large-scale farming.
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References
- Brenna et al. (2012). Sulfur Compounds in Fragrance Chemistry. Journal of Agricultural and Food Chemistry. DOI:10.1021/jf300236h
- International Fragrance Association (2021). Standard for Sulfur-Containing Fragrance Ingredients. IFRA Standards
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 34365-79-2Physical Properties
| Molecular Weight | 158.26 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2.9🔬 PubChem |
| Boiling Point | 236 °C🔬 EPA CompTox |
| log Kp (skin permeability) | -1.606💻 Calculated |
| SMILES | CC(C)SC(=O)C=C(C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
Odor & Flavor
| Primary Descriptors | greenonionsulfuroustropical• leffingwell |
| Functional Groups | alkene💻 RDKit |
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.
Physicochemical Properties
DTXSID: DTXSID1067837
Physical Properties
| Molecular Weight | 158.26 g/mol🔬 EPA CompTox |
| Density | 1.009 g/cm^3🔬 EPA CTX |
| Boiling Point | 236 °C🔬 EPA CTX |
| Melting Point | 32.182 °C📊 OPERA |
| Flash Point | 71.994 °C📊 OPERA |
| Refractive Index | 1.48 Dimensionless📊 OPERA |
| Molar Volume | 165.471 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.537 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.537 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.537 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.05 Log10 unitless📊 OPERA |
| Water Solubility | 0.006 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 1.408 mmHg📊 OPERA |
| Viscosity | 1.659 cP📊 OPERA |
| Surface Tension | 29.899 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 | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 46.998 cm^3/mol📊 OPERA |
| Polarizability | 18.631 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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