Methyl mercaptan (CAS 74-93-1) — Musky Top Note Fragrance Ingredient
Methyl mercaptan
CAS 74-93-1
What Is Methyl mercaptan?
Methyl mercaptan is a sulfur-containing compound that people rarely encounter directly but may notice in trace amounts in natural gas (as an odorant) or certain fermented foods. Despite its extremely low concentration in consumer products, it plays a crucial role in creating complex fragrance profiles. This potent molecule is used by perfumers in minute quantities to add animalic depth or tropical fruit nuances to compositions, demonstrating how even unpleasant-smelling ingredients can be transformative when skillfully blended.
Safety Profile
PROFESSIONAL USEWhat Does Methyl mercaptan Smell Like?
Methyl mercaptan assaults the nose with an intensely pungent, garlicky sulfurous character reminiscent of rotten cabbage or skunk spray. At ultra-dilute concentrations (parts per billion), it transforms into a complex tropical nuance – think durian fruit’s controversial allure or the sulfury top notes of passionfruit. In perfumery, it’s used in homeopathic doses to add animalic verve to chypres or create the illusion of fresh-cut tropical fruits. The molecule’s volatility means it disappears quickly, but its olfactory impact lingers, modifying how we perceive subsequent notes in the fragrance pyramid.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Methyl mercaptan contributes to the controversial tropical fruit accord, blending with cardamom and clove to create an unexpectedly addictive fragrance that walks the line between repulsive and irresistible.
Used here in a bold artistic statement, methyl mercaptan amplifies the blood-and-milk accord with its metallic sulfurous edge, creating one of perfumery’s most challenging compositions.
2D Molecular Structure
SMILES: CS
Chemistry, Properties & Perfumer Guide
The Chemistry
Methyl mercaptan (CH₃SH) is the simplest thiol, consisting of a methane group bonded to a sulfhydryl group. Industrially produced by reacting methanol with hydrogen sulfide over catalysts, this volatile compound is notorious for its extremely low odor threshold (0.002 ppm). The sulfur-hydrogen bond is responsible for both its penetrating odor and high reactivity. While naturally occurring in some foods and bodily processes, synthetic production allows precise control over purity for fragrance applications. The molecule’s small size and polarity contribute to its high volatility and water solubility.
Physical & Chemical Properties
| Boiling Point | 5.95 °C |
|---|---|
| Vapor Pressure | 1.5 atm at 20°C |
| Density | 0.8665 g/cm³ (liquid) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.0001-0.001% | Up to 0.005% | Used in parts-per-million for effect |
| Functional Fragrance | 0.00001% | Up to 0.0001% | Masking agent in industrial applications |
Classic Accords
Tip: Always pre-dilute to 0.1% or lower before incorporating into blends to avoid olfactory fatigue and overshooting.
Alternatives & Comparisons
Slightly less pungent with a more pronounced onion character, useful when a softer sulfur note is desired while maintaining tropical fruit effects.
Offers coffee-roasted sulfur nuances at higher concentrations but can mimic passionfruit at ultra-dilute levels with greater stability.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not specifically restricted by IFRA but falls under general thiol limitations. Use requires expert justification.
GHS Classification
RIFM Assessment
RIFM assessment recommends extreme caution due to toxicity profile, with usage only by qualified professionals in ventilated environments.
Sustainability
As an industrial chemical produced in controlled settings, methyl mercaptan’s environmental impact comes primarily from accidental releases rather than fragrance use. The minuscule quantities used in perfumery (typically micrograms per bottle) make its carbon footprint negligible compared to its functional role in gas leak detection systems that prevent methane emissions.
Explore Methyl mercaptan
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References
- Nagata Y. (2003). Measurement of odor threshold by triangle odor bag method. Japan Ministry of Environment.
- Arctander S. (1969). Perfume and Flavor Chemicals. Allured Publishing.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 74-93-1Physical Properties
| Molecular Weight | 48.11 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 0.5🔬 PubChem |
| Boiling Point | 5.9 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0075 mmHg @ 25°C📊 OPERA |
| Flash Point | -17.8 °C🔬 EPA CompTox |
| Involatility Index | 0.0012💻 Calculated |
| log Kp (skin permeability) | -2.638💻 Calculated |
| SMILES | CS🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 1.8 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | cabbage• leffingwell |
| Functional Groups | thiol💻 RDKit |
| “In spite of the extremely repulsive odor of this material, the human tolerance towards Methyl mercaptan is very high. Isolated cases of sickness from inhaling the gas are generally ascribed to psychological objection to the odor. The material is NOT classified as toxic.”📖 Arctander | |
| Methyl mercaptan has an objectionable odor of decomposing cabbage or garlic.📖 Fenaroli | |
Flavor Notes (Arctander)
| “It finds some use in flavor compositions, but more in the "reconstitution" of Coffee flavor. Particularly in products made from”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 0.0014 ppm (n=31)📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2716⚖️ FEMA GRAS |
| GRAS Status | Generally Recognized as Safe⚖️ FEMA GRAS |
| IOFI Classification | Nature Identical📖 Fenaroli |
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: DTXSID5026382
Physical Properties
| Molecular Weight | 48.1 g/mol🔬 EPA CompTox |
| Density | 0.939 g/cm^3🔬 EPA CTX |
| Boiling Point | 5.952 °C🔬 EPA CTX |
| Melting Point | -122.444 °C🔬 EPA CTX |
| Flash Point | -22.667 °C🔬 EPA CTX |
| Refractive Index | 1.408 Dimensionless📊 OPERA |
| Molar Volume | 59.09 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 0.979 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 0.979 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 0.974 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 1.35 Log10 unitless📊 OPERA |
| Water Solubility | 0.407 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0.003 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 1350.356 mmHg🔬 EPA CTX |
| Viscosity | 0.285 cP📊 OPERA |
| Surface Tension | 21.076 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 0 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 14.578 cm^3/mol📊 OPERA |
| Polarizability | 5.779 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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