5-Methyl-2-thiophenecarboxaldehyde (CAS 13679-70-4) — Spicy Middle Note Fragrance Ingredient

ByThe Good Scents
Spicy · Sweet

5-Methyl-2-thiophenecarboxaldehyde

CAS 13679-70-4

Origin
synthetic
Note
Middle
IFRA
Use with awareness
Data as of: Apr 2026

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 AWARENESS
Generally safeUse with awarenessProfessional use
⚠ Potential skin sensitizer – use caution
⚡ Avoid direct skin contact in pure form
CAS
13679-70-4
Formula
Mixture
MW
Variable
Odor Family
Spicy · Sweet
Layer 1 · Enthusiast

What 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.

Scent Profile

In Famous Fragrances

Fragrance associations may not reflect actual formulations.

Secretions Magnifiques(Etat Libre d’Orange, 2006)

Used to amplify the controversial blood-and-milk accord, contributing metallic sharpness that cuts through creamy lactones.

Black Afgano(Nasomatto, 2009)

Provides an asphalt-like edge to the cannabis accord, enhancing the fragrance’s dark, resinous character.

Layer 2

2D Molecular Structure

5-Methyl-2-thiophenecarboxaldehyde

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 Weight126.18 g/mol
Boiling PointEstimated 210-215°C

Perfumer Guide

Note Position
Middle
Volatility
Moderate (2-4 hours)
Blending
Challenging
ApplicationTypical %RangeNotes
Conceptual Fragrances0.01-0.1%Up to 0.3%For shock-value compositions
Leather Accords0.05-0.2%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

1
2-Methyl-3-furanthiol CAS 28588-74-1

When more pronounced meaty/gourmand effects are desired, though with greater volatility.

Layer 3

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

H315 Causes skin irritation H319 Causes serious eye irritation

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.

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References

  1. PubChem CID 13679-70-4 PubChem

Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.

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Ingredient Data Sheet

CAS 13679-70-4

Physical Properties

Molecular Weight126.18 g/mol🔬 PubChem
LogP (Octanol-Water)1.8🔬 PubChem
Boiling Point200 °C🔬 EPA CompTox
Vapor Pressure9.1201 mmHg @ 25°C📊 OPERA
Flash Point87.8 °C🔬 EPA CompTox
Involatility Index0.8751💻 Calculated
log Kp (skin permeability)-2.192💻 Calculated
SMILESCC1=CC=C(S1)C=O🔬 PubChem

Volatility & Performance

Fragrance NoteTop💻 Calculated
Volatility ClassModerate💻 Calculated
Persistence Score0.5 / 5💻 Calculated

Odor & Flavor

Primary Descriptorsalmondcherry• leffingwell
Functional Groupsaldehydearomatic💻 RDKit

Sensory Thresholds

Odor Detection Threshold0.0007 ppm📖 van Gemert

Regulatory Status

IOFI ClassificationNature Identical📖 Fenaroli
Data Sources & Attribution
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: 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.

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