Chlorphenesin (CAS 104-29-0)
Chlorphenesin: Structure, Properties, and Applications
1. Introduction
Chlorphenesin (CAS 104-29-0) is an organic compound used in medicine as a muscle relaxant and in the cosmetics industry as a preservative with antimicrobial properties. It exhibits bacteriostatic and fungicidal activity, making it a popular ingredient in various formulations. This article reviews its chemical structure, physicochemical properties, applications, safety, and regulatory status.
2. Chemical Structure and Nomenclature
Chemical name: 3-(4-Chlorophenoxy)propane-1,2-diol; 4-Chlorophenoxy-1,2-propanediol
Molecular formula: C₉H₁₁ClO₃
Molecular weight: 202.63 g/mol
CAS number: 104-29-0
EC number: 203-191-3
Appearance: White to off-white crystalline powder
3. Physicochemical Properties
Melting point: 77–82°C
Solubility: Slightly soluble in water (2.9 g/L at 20°C); soluble in ethanol, propylene glycol, and organic solvents
Log P: 1.46
Stability: Stable under normal conditions; may hydrolyze in acidic environments.
4. Mechanism of Action
Muscle relaxant: Chlorphenesin acts as a centrally acting muscle relaxant, reducing skeletal muscle tone and spasticity. The exact mechanism is not fully understood but is thought to involve effects on neuromuscular transmission.
Antimicrobial: Exhibits moderate activity against bacteria (especially Gram-positive) and fungi, making it suitable as a preservative in combination with other antimicrobial agents.
5. Applications
Medicine: Used as a centrally acting muscle relaxant for relieving muscle tension and pain. In some countries, its use has been limited or replaced by more modern agents.
Cosmetics: Used as a preservative in creams, lotions, and other personal care products to inhibit microbial growth in aqueous phases. Often combined with other preservatives (e.g., parabens) for synergistic effects.
Other applications: Occasionally used as an antimicrobial additive in coatings, emulsions, and agrochemical products.
6. Safety and Toxicology
General: Chlorphenesin is considered relatively safe when used within regulated concentration limits. However, it may cause skin and eye irritation.
Allergic reactions: May cause contact dermatitis or other skin irritation in sensitive individuals.
Regulatory limits: In cosmetics, maximum permitted concentrations vary by jurisdiction (typically up to 0.3–0.5% in formulations). Pharmaceutical forms also have specific regulations and warnings.
7. Interactions and Compatibility
Combination with other preservatives: Often used with parabens or phenoxyethanol to broaden antimicrobial spectrum and reduce individual dosages.
pH sensitivity: May decompose when mixed with acids or strongly alkaline components; pH control is important.
8. Research and Development Prospects
Alternative preservative systems: Research continues on milder, more natural alternatives, though chlorphenesin remains valued for its moderate cost and proven efficacy.
Improved safety profiles: Studies on encapsulation or combination with skin-barrier softening agents to reduce irritation potential.
Combination with antioxidants: Potential for use with vitamins and antioxidants for comprehensive formulation protection.
9. Regulatory Status
EU: Listed as an approved preservative in CosIng with concentration limits.
US: Used as a cosmetic ingredient; FDA requires labeling. Not widely used in pharmaceuticals.
Documentation: Safety Data Sheets (SDS) required for industrial use. Finished products must comply with national or regional quality standards.
10. Conclusion
Chlorphenesin (CAS 104-29-0) is a multifunctional organic compound combining muscle relaxant properties with antimicrobial activity. While its therapeutic use is relatively limited, it is widely used as a preservative in cosmetics. When concentrations and potential side effects are properly managed, chlorphenesin demonstrates a satisfactory safety and efficacy profile. Ongoing research focuses on improving its safety profile, reducing allergic potential, and developing new formulation strategies.