SDHS – Anionic Surfactant and Super-Wetter / Articles

Sodium Dihexyl Sulfosuccinate (CAS 3006-15-3): Properties and Applications

1. Introduction

Sodium dihexyl sulfosuccinate (SDHS) is an anionic surfactant belonging to the sulfosuccinate family. It is known for its ability to significantly reduce surface tension at very low concentrations, earning it the designation of a "super-wetter" in industrial literature. This compound is widely used as a wetting agent, emulsifier, dispersant, and solubilizer across various industries, including household cleaners, agrochemicals, emulsion polymerization, electroplating, and textile processing.

2. Chemical Structure and Nomenclature

IUPAC name: Sodium; 1,4-dihexoxy-1,4-dioxobutane-2-sulfonate

Molecular formula: C₁₆H₂₉NaO₇S (or C₁₆H₃₀NaO₇S)

Molecular weight: 388.45–389.5 g/mol

CAS number: 3006-15-3

EC number: 221-109-1

Synonyms: Dihexyl sodium sulfosuccinate, Sodium 1,4-dihexyl sulfonatosuccinate, 2-Sulfosuccinic acid di-N-hexyl ester sodium salt, Aerosol MA, Aerosol MA 80, EMPIMIN MA 80, Monawet MM-80

Appearance: Off-white to pale yellow powder or granules; also available as a yellowish to brownish liquid (typically 80% aqueous solution)

3. Physicochemical Properties

Melting point: 230°C (decomposes)

Density: 1.121 g/mL (liquid formulation)

Solubility: Highly soluble in water (364 g/L at 20°C); also soluble in alcohols and some organic solvents

pH (5% aqueous solution): 5–7 (neutral to slightly acidic)

Assay (purity): ≥98.5% (on anhydrous substance)

Surface activity: Reduces surface tension at very low concentrations; forms micelles at the critical micelle concentration (CMC)

Resistance: High resistance to radiation and oxidation

4. Mechanism of Action

Sodium dihexyl sulfosuccinate is an amphiphilic molecule with a hydrophilic sulfonate head group and two hydrophobic hexyl tails. This structure allows it to adsorb at interfaces, significantly lowering surface and interfacial tension. At low concentrations, SDHS acts as a "super-wetter" by reducing the surface tension of aqueous solutions. As concentration increases, the molecules self-assemble into micelles, enabling the solubilization and dispersion of hydrophobic substances.

5. Applications

Household and industrial cleaners: Used as a wetting agent and penetrant in glass cleaners, paint strippers, and hard surface cleaners. Acts as an emulsifier and dispersant for waxes and polishes.

Agrochemicals: Functions as a wetting and spreading agent in pesticide formulations to improve coverage and penetration on plant surfaces.

Emulsion polymerization: Used to produce fine particle size polymer dispersions and as an emulsifier in waterborne industrial coatings, acrylics, and printing inks.

Electroplating: Commonly used as an anti-pitting and wetting agent in electrolytic nickel plating baths.

Textile processing: Acts as a textile wetting agent and penetrant.

Adhesives and sealants: Used as an emulsifier in food packaging adhesives and closure-sealing gaskets.

Laboratory and research: Used as a surfactant in scientific research to facilitate emulsification and dispersion of substances in aqueous solutions.

6. Safety and Toxicology

Acute oral toxicity: LD₅₀ (rat) = 1750 mg/kg. Classified as harmful if swallowed (H302).

Skin and eye irritation: May cause irritation to skin, eyes, and respiratory tract.

Inhalation: Vapors may cause drowsiness and dizziness.

Environmental: May be harmful to aquatic organisms; shows poor biodegradability and limited mineralization.

Regulatory status: Subject to REACH regulation in the EU; requires Safety Data Sheets (SDS) for industrial handling.

7. Advantages and Limitations

Advantages:

Exceptional wetting ability at very low concentrations ("super-wetter").
Effective emulsifier and dispersant for a wide range of applications.
High resistance to oxidation and radiation.
Soluble in water and organic solvents.
Available in various formulations (powder, granules, aqueous solution).

Limitations:

Poor biodegradability.
Potential for skin and eye irritation.
Harmful to aquatic organisms.
May hydrolyze in alkaline solutions.

8. Conclusion

Sodium dihexyl sulfosuccinate (CAS 3006-15-3) is a versatile anionic surfactant valued for its exceptional wetting, emulsifying, and dispersing properties. Its ability to significantly reduce surface tension at low concentrations makes it a key ingredient in cleaners, agrochemicals, emulsion polymerization, electroplating, and textile processing. While its performance benefits are significant, its poor biodegradability and potential for irritation require careful handling and environmental consideration. Ongoing research continues to explore new formulations and synergistic combinations to optimize its effectiveness while minimizing environmental impact.