1,2-Benzisothiazol-3(2H)-one (CAS 2634-33-5) — Green N/A Note Fragrance Ingredient
1,2-Benzisothiazol-3(2H)-one
CAS 2634-33-5
What Is 1,2-Benzisothiazol-3(2H)-one?
1,2-Benzisothiazol-3(2H)-one is a synthetic preservative commonly found in industrial products like paints, adhesives, and some personal care items. It prevents microbial growth in water-based formulations. This ingredient matters because it extends product shelf life but requires careful handling due to its potent antimicrobial properties.
Safety Profile
USE WITH AWARENESSWhat Does 1,2-Benzisothiazol-3(2H)-one Smell Like?
This compound has a sharp, chemical odor with pronounced bitterness, reminiscent of industrial disinfectants. The scent profile is linear without noticeable evolution, maintaining a persistent, acrid character. It lacks the complexity of natural fragrances, presenting instead a straightforward, functional aroma designed for preservation rather than pleasure.
2D Molecular Structure
SMILES: O=C1NSC2=C1C=CC=C2
Chemistry, Properties & Perfumer Guide
The Chemistry
1,2-Benzisothiazol-3(2H)-one is a heterocyclic compound containing both nitrogen and sulfur atoms. It belongs to the isothiazolone class of biocides. Industrially synthesized through ring-closure reactions of ortho-substituted benzamides, its antimicrobial activity stems from the reactive N-S bond disrupting microbial cell functions. The molecule exhibits moderate stability in aqueous solutions but degrades under strong UV light.
Physical & Chemical Properties
| Appearance | Pale yellow liquid |
|---|---|
| Boiling Point | Decomposes before boiling |
| Solubility | Soluble in organic solvents, partially in water |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Industrial Preservatives | 0.05-0.2% | Up to 0.5% | Effective against bacteria and fungi |
| Personal Care | 0.02-0.1% | Up to 0.15% | Limited use due to sensitization potential |
Classic Accords
Tip: Always incorporate this preservative during the cooling phase of emulsion preparation.
Alternatives & Comparisons
Used when broader spectrum antimicrobial activity is needed, but with higher sensitization risk.
Gentler preservative for leave-on products where benzisothiazolinone would be too harsh.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted by IFRA but subject to concentration limits in cosmetic applications.
EU Allergen Declaration
Not classified as an EU allergen but requires declaration above 0.0015% in leave-on products.
GHS Classification
RIFM Assessment
RIFM has assessed this compound as safe at current use levels in industrial applications, but with strict concentration limits for personal care.
Sustainability
This synthetic biocide is not biodegradable and poses risks to aquatic ecosystems. Industrial wastewater treatment is required before disposal. Manufacturers are developing more eco-friendly preservation systems to replace traditional isothiazolinones.
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References
- EU Scientific Committee on Consumer Safety (2014). Opinion on 1,2-Benzisothiazol-3(2H)-one. SCCS/1525/14
- PubChem Compound Summary for 1,2-Benzisothiazol-3(2H)-one CID 76347
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 2634-33-5Physical Properties
| Molecular Weight | 151.19 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.3🔬 PubChem |
| Boiling Point | 327.6 °C🔬 EPA CompTox |
| Vapor Pressure | 2.78 mmHg @ 25°C📊 OPERA |
| Flash Point | 77.5 °C🔬 EPA CompTox |
| Involatility Index | 0.2437💻 Calculated |
| log Kp (skin permeability) | -2.699💻 Calculated |
| SMILES | C1=CC=C2C(=C1)C(=O)NS2🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Moderate💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Functional Groups | aromatic💻 RDKit |
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: DTXSID5032523
Physical Properties
| Molecular Weight | 151.18 g/mol🔬 EPA CompTox |
| Density | 1.468 g/cm^3🔬 EPA CTX |
| Boiling Point | 331.933 °C🔬 EPA CTX |
| Melting Point | 150.9 °C🔬 EPA CTX |
| Flash Point | 77.575 °C🔬 EPA CTX |
| Refractive Index | 1.661 Dimensionless📊 OPERA |
| Molar Volume | 110.533 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 0.639 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 0.822 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -0.061 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 8.36 Log10 unitless📊 OPERA |
| Water Solubility | 0.02 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0 mmHg🔬 EPA CTX |
| Surface Tension | 52.982 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 32.86 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 2 count💻 Computed |
| Molar Refractivity | 40.844 cm^3/mol📊 OPERA |
| Polarizability | 16.192 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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