3,4-Dimethylthiophene (CAS 632-15-5) — Woody Middle Note Fragrance Ingredient
3,4-Dimethylthiophene
CAS 632-15-5
What Is 3,4-Dimethylthiophene?
3,4-Dimethylthiophene is a synthetic sulfur-containing compound used in specialty fragrances. It’s found in trace amounts in some roasted foods and coffee, contributing to their complex aromas. This ingredient matters because it adds a unique meaty, savory nuance to modern perfumery, especially in niche and avant-garde compositions where unconventional notes are prized.
Safety Profile
USE WITH AWARENESSWhat Does 3,4-Dimethylthiophene Smell Like?
3,4-Dimethylthiophene delivers an intensely savory, almost brothy aroma with strong meaty undertones reminiscent of roasted beef or pan-seared mushrooms. Its sulfurous character emerges as a sharp, pungent top note that quickly mellows into a warm, umami-like heart. The dry-down reveals subtle smoky nuances that blend surprisingly well with woody and amber bases, though its persistence is moderate at best. This challenging material requires skillful blending to prevent overwhelming a composition, but when used judiciously, it adds remarkable depth and modernity to fragrances.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the controversial blood-like metallic notes, contributing to the fragrance’s visceral, bodily character that polarized critics and audiences alike.
Provides a dark, resinous smokiness that enhances the fragrance’s namesake cannabis accord, adding leathery depth to the woody-amber base.
Contributes charred, smoky facets that play against the traditional fougère structure, creating the illusion of burning barbershop products.
2D Molecular Structure
SMILES: CC1=CSC=C1C
Chemistry, Properties & Perfumer Guide
The Chemistry
3,4-Dimethylthiophene belongs to the thiophene class of heterocyclic compounds, characterized by a five-membered ring containing sulfur. While thiophenes occur naturally in petroleum and some foods, this specific dimethylated variant is predominantly synthetic. It’s typically prepared via the Paal-Knorr thiophene synthesis or through catalytic hydrodesulfurization of heavier petroleum fractions. The molecule’s planar structure and electron-rich sulfur atom contribute to its potent aroma characteristics, while the methyl groups influence volatility and odor tenacity.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | ~140-145 °C (estimated) |
| Density | ~1.02 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.01-0.1% | Up to 0.3% | Used as trace modifier for smoky-meaty effects |
| Functional Fragrance | 0.001-0.01% | None | Rarely used outside specialty applications |
Classic Accords
Tip: Always pre-dilute to 1% or lower before incorporating into blends due to potency.
Alternatives & Comparisons
For more pronounced meaty notes with less sulfur harshness, though requires even greater caution in handling due to extreme potency.
Provides similar savory character but with more fruity-browned butter nuances, useful when a softer sulfur effect is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA, though sulfur compounds generally fall under Note 11 (Sulfur-containing compounds) requiring safety evaluation.
GHS Classification
RIFM Assessment
Not formally evaluated by RIFM, though structurally similar thiophenes show moderate skin sensitization potential in animal studies.
Sustainability
As a synthetic compound derived from petrochemical feedstocks, 3,4-Dimethylthiophene raises typical sustainability concerns associated with fossil fuel dependence. However, its extreme potency means very small quantities are used, minimizing environmental load. Some manufacturers are exploring bio-based synthesis routes using sugar fermentation byproducts as alternative feedstocks.
Explore 3,4-Dimethylthiophene
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References
- McGorrin (2011). The Significance of Volatile Sulfur Compounds in Food Flavors. ACS Symposium Series. ACS Publication
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID40212549
Physical Properties
| Molecular Weight | 112.19 g/mol🔬 EPA CompTox |
| Density | 1.005 g/cm^3🔬 EPA CTX |
| Boiling Point | 145 °C🔬 EPA CTX |
| Melting Point | -46.061 °C📊 OPERA |
| Flash Point | 28.258 °C📊 OPERA |
| Refractive Index | 1.527 Dimensionless📊 OPERA |
| Molar Volume | 111.463 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.658 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.658 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.658 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.77 Log10 unitless📊 OPERA |
| Water Solubility | 0.008 mol/L📊 OPERA |
| Henry's Law Constant | 0.007 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 8.887 mmHg📊 OPERA |
| Viscosity | 1.748 cP📊 OPERA |
| Surface Tension | 31.396 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 0 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 34.287 cm^3/mol📊 OPERA |
| Polarizability | 13.592 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.
