Ethyl P-Hydroxybenzoate BP EP USP Pharma Grade: Detailed Overview of Its Physical and Chemical Profile

What is Ethyl P-Hydroxybenzoate?

Ethyl P-Hydroxybenzoate stands out as a potent preservative, recognized under various regulatory standards including BP (British Pharmacopoeia), EP (European Pharmacopoeia), and USP (United States Pharmacopeia). Often named Ethylparaben in industrial circles, this compound appears in pharmaceutical, food, and cosmetic applications. Chemists know it for its reliable capacity to deter microbial growth, protecting sensitive formulations from bacterial and fungal contamination. It sports the molecular formula C9H10O3 and the IUPAC name ethyl 4-hydroxybenzoate. The structure includes a benzene ring attached to a hydroxy group at the para position and an ethyl ester group—a combination yielding not just antimicrobial capability but also a straightforward synthesis.

Physical Characteristics

This compound typically presents as a white or nearly white crystalline powder, solid flakes, or small pearls. Many samples offer a fine, odorless powder, easing the blending with other materials. Crystals show a defined structure under magnification. Density ranges from approximately 1.2 to 1.3 g/cm³, and melting points hover near 115°C to 118°C. Solubility becomes a practical consideration—sparingly soluble in water, yet readily dissolves in alcohol, ether, acetone, and other organic solvents. Its stability under ordinary storage conditions makes it a first choice for manufacturers needing shelf-life extension without compromising the end product's consistency. The pH of a saturated aqueous solution usually lands between 4 and 5, which supports its preservative effect.

Chemical Properties and Behavior

Chemically, Ethyl P-Hydroxybenzoate demonstrates resistance to light and air under standard conditions. It remains stable at neutral or slightly acidic pH, and decomposition generally requires substantial heating or strong alkali. The compound resists hydrolysis unless exposed to highly basic environments, a trait that enables reliable preservation for creams, syrups, and suspensions. This substance carries a CAS Number of 120-47-8 and a Harmonized System (HS) Code often assigned as 29182900, aligning it with carboxylic acid derivatives. Molecular weight measures about 166.18 g/mol.

Specifications and Standards

Industry benchmarks for Ethyl P-Hydroxybenzoate enforce tight controls on its purity, moisture content, and appearance. Standards usually require an assay (pure content) of not less than 99.0% and not more than 101.0% by dried substance. Chloride and sulfate levels must fall below specified thresholds to avoid adverse interactions in pharmaceutical recipes. Residue on ignition, heavy metals, and related substances undergo routine checks, since the presence of these can influence the safety profile. Regulations demand labeling and documentation in line with global chemical transportation conventions for clarity across the supply chain.

Forms and Applications

Ethyl P-Hydroxybenzoate appears in many physical forms—powder, solid flakes, or crystalline pearls. Each shape serves specific manufacturing needs. Powders blend easily into dry mixes, while flakes or pearls simplify metering into liquid formulations. Because the compound tolerates routine handling, it flows evenly during automated processing and rarely clumps under reasonable humidity. Solution preparation becomes effortless; quick dissolution in alcohol solutions ensures rapid dispersal in product bases such as syrups or gels. Its low odor and color stability protect finished goods from sensory changes, which can matter deeply in food and pharmaceutical packaging.

Material Handling, Safety, and Hazards

Though considered safe within permitted concentration ranges, Ethyl P-Hydroxybenzoate warrants careful handling like all raw materials in pharmaceutical environments. Workers should avoid inhalation of fine particulates to prevent potential respiratory irritation. Contact with skin or eyes seldom causes more than mild irritation, but routine use of gloves and goggles aligns with industry best practice. Regulatory agencies classify this compound with low acute toxicity. Large-scale spills call for sweeping and collection while minimizing dust release; solutions dissolve easily in standard clean-up protocols. Safe storage requires tight-sealing containers kept away from direct sunlight and excessive moisture. Waste management involves authorized disposal procedures to avoid environmental accumulation.

Role in Manufacturing and the Broader Chemical Industry

Ethyl P-Hydroxybenzoate helps ensure hygiene and longevity in pharmaceuticals, topical medicines, suspensions, syrups, as well as food packaging and certain cosmetic formulations. Manufacturers select the pharma grade to comply with international specifications on purity and contaminant limits. Proper identification of raw materials under the correct HS Code, and clear tracking from sourcing through processing, reinforces global supply chain integrity. With its physical stability, dependable antimicrobial properties, and low reactivity with excipients, it supports safe product development on a large scale. Experienced operations teams rely on valid certificates of analysis and transparent documentation to confirm each lot meets the intended use—reminding us that chemistry, regulation, and practical caution always go hand in hand.