Benzethonium Chloride (CAS 121-54-0) / Articles

Benzethonium Chloride (CAS 121-54-0): Properties and Applications

1. Introduction

Benzethonium chloride is a cationic surfactant belonging to the quaternary ammonium compound group. It is known for its strong bactericidal and fungicidal activity, making it widely used in medicine, cosmetics, personal care, and household disinfection. Its antimicrobial properties, combined with surface-active characteristics, make it a versatile ingredient in various formulations.

2. Chemical Structure and Properties

Chemical name: Benzyldimethyl[2-[2-[4-(1,1,3,3-tetramethylbutyl)phenoxy]ethoxy]ethyl]ammonium chloride

Molecular formula: C₂₇H₄₂ClNO₂

Molecular weight: 448.08 g/mol

CAS number: 121-54-0

EC number: 204-479-9

Appearance: White crystalline powder

Solubility: Soluble in water and ethanol

Stability: Stable under normal storage conditions

3. Mechanism of Antimicrobial Action

Benzethonium chloride acts by disrupting microbial cell membranes. The cationic portion of the molecule interacts with negatively charged phospholipids on the bacterial cell surface, increasing membrane permeability and leading to cell lysis. This mechanism provides broad-spectrum activity against Gram-positive and Gram-negative bacteria, fungi, and some viruses. The surfactant properties also enhance its ability to penetrate and wet surfaces.

4. Applications

Medicine: Used in antiseptic solutions, wound cleansers, disinfectant wipes, and some topical ointments. Also found in some feminine hygiene products.

Cosmetics and personal care: Used as a preservative and antimicrobial agent in creams, lotions, deodorants, antiperspirants, and shampoos. Provides both preservation and antimicrobial protection.

Household and industrial disinfectants: A key ingredient in surface disinfectants, instrument sterilizers, and cleaning products for healthcare facilities, food service establishments, and public sanitation.

Ophthalmology: Occasionally used as a preservative in ophthalmic solutions (though less commonly than benzalkonium chloride).

5. Safety and Toxicology

Skin irritation: May cause irritation at high concentrations; generally safe at concentrations up to 0.1–0.2% in cosmetics.

Ocular irritation: Can cause significant eye irritation; avoid contact with eyes.

Oral toxicity: Toxic if ingested in large quantities.

Allergenic potential: May cause allergic reactions in sensitive individuals.

Regulatory status: Approved for use in cosmetics in the US, EU, and many other countries at specified concentration limits.

6. Advantages and Limitations

Advantages:

Broad-spectrum antimicrobial activity.
Effective at low concentrations.
Good water and alcohol solubility.
Long-lasting antimicrobial effect on treated surfaces.
Compatible with many non-ionic surfactants.

Limitations:

Incompatible with anionic surfactants.
May cause irritation at high concentrations.
Potential for microbial resistance.
Requires careful formulation to avoid precipitation.

7. Conclusion

Benzethonium chloride (CAS 121-54-0) is a versatile cationic surfactant and antimicrobial agent widely used in medicine, cosmetics, and disinfection. Its broad-spectrum activity, effectiveness at low concentrations, and good solubility make it a valuable ingredient in many formulations. When used within recommended concentration limits, it provides safe and effective antimicrobial protection. Ongoing research continues to explore new formulations and applications for this well-established quaternary ammonium compound.