2-Mercaptopropionic acid (CAS 79-42-5) — Spicy N/A Note Fragrance Ingredient
2-Mercaptopropionic acid
CAS 79-42-5
What Is 2-Mercaptopropionic acid?
2-Mercaptopropionic acid is a synthetic compound primarily used in industrial applications and niche perfumery. It’s not commonly encountered in everyday products. This ingredient is valued in fragrance chemistry for its unique sulfur-containing structure, which can contribute to certain olfactory effects despite not being widely used in consumer products.
Safety Profile
PROFESSIONAL USEWhat Does 2-Mercaptopropionic acid Smell Like?
2-Mercaptopropionic acid has a sharp, acrid odor characteristic of thiol compounds, with a pronounced sulfurous quality that can be reminiscent of burnt rubber or garlic at high concentrations. Its volatility makes it a challenging material to work with, often requiring dilution to be useful in fragrance applications where it might contribute to creating certain meaty or savory nuances in trace amounts.
2D Molecular Structure
SMILES: CC(S)C(O)=O
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Mercaptopropionic acid is a thiol-containing carboxylic acid, structurally similar to propionic acid but with a sulfur substitution. It’s produced through synthetic routes, typically by the addition of hydrogen sulfide to acrylic acid derivatives. The thiol group makes it reactive and capable of forming disulfide bonds. Its acidity and sulfur content make it more useful as a chemical intermediate than as a direct fragrance material.
Physical & Chemical Properties
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Industrial | Trace | None | Not typically used in perfumery |
| Research | Trace | None | Specialized applications only |
Classic Accords
Tip: Extreme caution required – this material is not suitable for standard perfumery applications.
Alternatives & Comparisons
A more perfumery-friendly thiol compound used to create tropical fruit nuances.
Used in coffee and roasted food flavors, with better fragrance applications.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not evaluated by IFRA – not used in commercial perfumery.
GHS Classification
RIFM Assessment
No RIFM evaluation – not used in consumer fragrance products.
Sustainability
As an industrial chemical, 2-mercaptopropionic acid is produced synthetically with standard petrochemical feedstocks. Its environmental impact is primarily related to its production process rather than end-use applications, given its limited use in fragrance formulations.
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Ingredient Data Sheet
CAS 79-42-5Physical Properties
| Molecular Weight | 106.15 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 0.5🔬 PubChem |
| Boiling Point | 117 °C🔬 EPA CompTox |
| Vapor Pressure | 0.1155 mmHg @ 25°C📊 OPERA |
| Flash Point | 118 °C🔬 EPA CompTox |
| Involatility Index | 0.0121💻 Calculated |
| log Kp (skin permeability) | -2.993💻 Calculated |
| SMILES | CC(C(=O)O)S🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Slow💻 Calculated |
| Persistence Score | 1 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | sulfurous• leffingwell |
| Functional Groups | thiol💻 RDKit |
| Thiolactic acid has a roasted, meaty odor.📖 Fenaroli | |
Regulatory Status
| 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: DTXSID80861636
Physical Properties
| Molecular Weight | 106.14 g/mol🔬 EPA CompTox |
| Density | 1.196 g/cm^3🔬 EPA CTX |
| Boiling Point | 207.7 °C🔬 EPA CTX |
| Melting Point | 12.873 °C🔬 EPA CTX |
| Flash Point | 118 °C🔬 EPA CTX |
| Refractive Index | 1.494 Dimensionless📊 OPERA |
| Molar Volume | 87.106 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.15 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | -1.997 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -3.661 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.24 Log10 unitless📊 OPERA |
| Water Solubility | 0.624 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.096 mmHg🔬 EPA CTX |
| Viscosity | 1.991 cP📊 OPERA |
| Surface Tension | 35.771 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 37.3 Ų💻 Computed |
| H-Bond Donors | 2 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 1 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 25.367 cm^3/mol📊 OPERA |
| Polarizability | 10.056 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.
