4-(Methylthio)-4-methyl-2-pentanone (CAS 23550-40-5) — Citrus Top to middle Note Fragrance Ingredient
4-(Methylthio)-4-methyl-2-pentanone
CAS 23550-40-5
What Is 4-(Methylthio)-4-methyl-2-pentanone?
4-(Methylthio)-4-methyl-2-pentanone is a synthetic fragrance ingredient used in perfumery for its unique sulfurous-fruity character. You’ll encounter it in modern citrus and tropical fragrances. This molecule matters because it adds a distinctive ‘blackcurrant bud’ effect without using natural extracts, making fragrances more sustainable while maintaining complexity.
Safety Profile
USE WITH AWARENESSWhat Does 4-(Methylthio)-4-methyl-2-pentanone Smell Like?
A paradoxical burst of sulfurous blackcurrant buds morphing into tropical guava flesh, with an underlying sweaty-musky animalic edge. Opens with sharp cassis-like intensity (think crushed blackcurrant leaves), then evolves into a jammy fruitiness reminiscent of overripe passionfruit. The dry-down reveals a lingering sulfuraceous warmth that adds body to citrus compositions. At high concentrations, develops a rubbery, almost onion-like sulfonic character that requires careful dosing.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to amplify the blackcurrant-cassis effect in the citrus opening, adding a modern sulfuraceous twist to the classic cologne structure.
Provides a dark fruity facet that bridges between the chocolatey base and floral heart, enhancing the fragrance’s mysterious depth.
2D Molecular Structure
SMILES: CSC(C)(C)CC(C)=O
Chemistry, Properties & Perfumer Guide
The Chemistry
A branched-chain thioether ketone with molecular formula C7H14OS. The methylthio group (-SCH3) at the 4-position creates strong sulfurous notes, while the ketone provides fruity character. Synthesized via nucleophilic substitution of methyl mercaptan on methyl isobutyl ketone derivatives. The steric hindrance from the branched structure affects volatility and odor strength. No chiral centers present.
Physical & Chemical Properties
| Boiling Point | ~200 °C (estimated) |
|---|---|
| Density | ~0.95 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Powerful modifier |
| Functional Fragrance | 0.01-0.1% | Up to 0.2% | For tropical fruit effects |
Classic Accords
Tip: Balance with ionones to tame the sulfurous edge while preserving fruity character.
Alternatives & Comparisons
For more tropical passionfruit effects with less sulfur harshness, though lacks the cassis nuance.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific restrictions under IFRA 49th Amendment. General sulfur compound guidelines apply.
GHS Classification
RIFM Assessment
RIFM assessment pending. Currently approved for use based on structural analogs.
Sustainability
Synthetic production avoids agricultural land use. The sulfur content requires careful wastewater treatment during manufacturing. More sustainable than natural blackcurrant bud absolute which requires large plant material quantities.
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References
- Brenna et al. (2002). Sulfur Compounds in Fragrance Chemistry. Perfumer & Flavorist.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 23550-40-5Physical Properties
| Molecular Weight | 146.25 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.1🔬 PubChem |
| Boiling Point | 78 °C🔬 EPA CompTox |
| log Kp (skin permeability) | -2.811💻 Calculated |
| SMILES | CC(=O)CC(C)(C)SC🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
Odor & Flavor
| Primary Descriptors | fruitygreen• leffingwell |
| Functional Groups | ketone💻 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: DTXSID0066905
Physical Properties
| Molecular Weight | 146.25 g/mol🔬 EPA CompTox |
| Density | 0.964 g/cm^3🔬 EPA CTX |
| Boiling Point | 195.414 °C📊 OPERA |
| Melting Point | -8.997 °C📊 OPERA |
| Flash Point | 62.557 °C📊 OPERA |
| Refractive Index | 1.459 Dimensionless📊 OPERA |
| Molar Volume | 155.22 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.366 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.366 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.366 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.32 Log10 unitless📊 OPERA |
| Water Solubility | 0.093 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 2.715 mmHg📊 OPERA |
| Viscosity | 1.6 cP📊 OPERA |
| Surface Tension | 28.302 dyn/cm📊 OPERA |
| Thermal Conductivity | 122.034 mW/(m*K)📊 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 | 3 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 42.471 cm^3/mol📊 OPERA |
| Polarizability | 16.837 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.
