5-Methyl-2-thiophenecarboxaldehyde (CAS 13679-70-4) — Spicy Middle Note Fragrance Ingredient
5-Methyl-2-thiophenecarboxaldehyde
CAS 13679-70-4
What Is 5-Methyl-2-thiophenecarboxaldehyde?
5-Methyl-2-thiophenecarboxaldehyde is a synthetic aromatic compound used in modern perfumery to add warm, spicy nuances with a sulfurous edge. It’s found in niche fragrances aiming for unconventional compositions. This ingredient matters because it bridges gourmand and animalic profiles, offering perfumers a tool to create intriguing contrasts in avant-garde scents.
Safety Profile
USE WITH AWARENESSWhat Does 5-Methyl-2-thiophenecarboxaldehyde Smell Like?
A complex interplay of roasted coffee beans, toasted nuts, and a whisper of burnt rubber. Opens with sharp, sulfury top notes reminiscent of struck matches, settling into a heart of caramelized onions and black truffle. The dry-down reveals a lingering umami depth akin to aged soy sauce, with faint leathery undertones that add sophistication to unconventional accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to amplify the controversial blood-and-milk accord, contributing metallic sharpness that cuts through creamy lactones.
Provides an asphalt-like edge to the cannabis accord, enhancing the fragrance’s dark, resinous character.
2D Molecular Structure
SMILES: CC1=CC=C(S1)C=O
Chemistry, Properties & Perfumer Guide
The Chemistry
A thiophene derivative where the aldehyde group at position 2 and methyl group at position 5 create unique electronic effects. The sulfur atom contributes significant odor potency at minute concentrations. Typically synthesized via Vilsmeier-Haack formylation of 2-methylthiophene, requiring careful control due to reactivity. The planar structure allows for π-stacking in fragrance matrices, influencing longevity.
Physical & Chemical Properties
| Molecular Weight | 126.18 g/mol |
|---|---|
| Boiling Point | Estimated 210-215°C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Conceptual Fragrances | 0.01-0.1% | Up to 0.3% | For shock-value compositions |
| Leather Accords | 0.05-0.2% | Up to 0.5% | To create burnt effects |
Classic Accords
Tip: Always pre-dilute to 1% in DPG before incorporation due to extreme potency.
Alternatives & Comparisons
When more pronounced meaty/gourmand effects are desired, though with greater volatility.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA standards. Listed as Category B – Limited Data Available (49th Amendment).
EU Allergen Declaration
Not listed in EU allergen regulation (EC) No 1223/2009.
GHS Classification
RIFM Assessment
Under evaluation by RIFM (2023). Preliminary data suggests moderate skin sensitization potential at >0.5% concentration.
Sustainability
Synthesized from petroleum derivatives with significant energy input. No known natural sources. Waste streams require specialized sulfur-scrubbing treatment. Carbon footprint estimated at 8-12 kg CO2e/kg produced.
Explore 5-Methyl-2-thiophenecarboxaldehyde
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References
- PubChem CID 13679-70-4 PubChem
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID0047169
Physical Properties
| Molecular Weight | 126.17 g/mol🔬 EPA CompTox |
| Density | 1.175 g/cm^3🔬 EPA CTX |
| Boiling Point | 203.587 °C📊 OPERA |
| Melting Point | 39.998 °C📊 OPERA |
| Flash Point | 75.551 °C📊 OPERA |
| Refractive Index | 1.593 Dimensionless📊 OPERA |
| Molar Volume | 106.854 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.51 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 1.51 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.51 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.52 Log10 unitless📊 OPERA |
| Water Solubility | 0.057 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 3.223 mmHg📊 OPERA |
| Viscosity | 2.215 cP📊 OPERA |
| Surface Tension | 42.225 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 | 1 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 36.215 cm^3/mol📊 OPERA |
| Polarizability | 14.357 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.
