Butylparaben (Butyl 4-hydroxybenzoate) - CAS 94-26-8
Butylparaben (Butyl 4-Hydroxybenzoate, CAS 94-26-8): Overview
1. Introduction
Butylparaben (Butyl p-hydroxybenzoate, CAS 94-26-8) belongs to the paraben group – esters of para-hydroxybenzoic acid widely used as preservatives. Due to its antimicrobial properties, butylparaben is extensively used in the pharmaceutical, food, and cosmetic industries. Optimal effectiveness and ease of use make this compound one of the key preservatives in the production of various products.
2. Chemical Structure and Properties
Structure: Molecular formula C₁₁H₁₄O₃. It is the butyl ester of para-hydroxybenzoic acid – the benzoic ring has a hydroxyl group in the para position, and the carboxyl group is esterified with a butyl radical.
Physical characteristics: Melting point typically around 68–71°C. Low solubility in water, but good solubility in alcohols and oils. Stable within weakly acidic and neutral pH ranges.
Stability: Butylparaben retains activity across a wide temperature range and does not undergo rapid degradation when properly stored. May exhibit higher efficacy in combination with other parabens.
3. Mechanism of Antimicrobial Action
Butylparaben, like other parabens, inhibits microbial growth by destabilizing cell membranes and inhibiting enzymatic processes. Upon incorporation into the aqueous or oil phase of a formulation, the ester molecules of para-hydroxybenzoic acid interact with membrane lipids of bacteria, fungi, and yeasts. This disrupts the integrity of the cell wall and membrane, leading to microbial death.
4. Main Areas of Application
Pharmaceuticals: Used for preserving syrups, creams, ointments, and some injectable solutions. Effective against a broad spectrum of bacteria and fungi, extending the shelf life of medicinal products.
Cosmetic industry: Creams, lotions, shampoos, and decorative cosmetics. Combined with methylparaben or propylparaben for enhanced effect.
Food industry: May be used as a preservative in certain products under strict regulatory compliance. Inhibits mold and bacterial growth, improving product stability.
5. Safety and Recommendations for Use
Dosages: Recommended concentrations typically range from 0.01% to 0.4% depending on the product type. When used in combination with other parabens, the total proportion of each substance must comply with regulatory requirements.
Allergic reactions: In rare cases, sensitive individuals may experience skin reactions (contact dermatitis). Compatibility testing is recommended when introducing into new formulations, especially in cosmetic products.
Registration and control: Butylparaben is officially approved for use in many countries, but maximum permitted concentrations are established. Ongoing research continues to clarify data on potential endocrine effects.
6. Conclusion
Butylparaben (Butyl 4-hydroxybenzoate) is a time-tested preservative that effectively controls microbial growth in various products. Good solubility in organic media and compatibility with other parabens make it convenient for formulation. At the same time, discussions on the safety of parabens are driving the development of alternative solutions and further study of optimal concentrations. When used within recommended limits, butylparaben helps ensure the stability and quality of pharmaceutical, food, and cosmetic products.