Description

3,5-Di-tert-Butyl-4-Hydroxybenzylphosphonic Acid Monoethyl Ester is a high-performance phenolic phosphite antioxidant and processing stabilizer. This compound is valued for its ability to effectively inhibit thermal and oxidative degradation in polymers, thereby extending material lifespan and maintaining performance under demanding conditions. It is primarily needed by manufacturers in the polymer and plastics industries, especially for stabilizing polyolefins, engineering plastics, and synthetic rubbers against degradation during high-temperature processing and long-term use.

Application

• Primary antioxidant and processing stabilizer for polypropylene (PP) and polyethylene (PE).
• Synergistic stabilizer in combination with hindered amine light stabilizers (HALS) for enhanced long-term thermal aging resistance.
• Stabilization of engineering plastics such as polyamides (PA) and polyesters (PBT, PET) during extrusion and injection molding.
• Protection of synthetic elastomers and adhesives from oxidative cross-linking and chain scission.
• Additive in lubricant and grease formulations to prevent oxidation and viscosity increase.
• Intermediate in the synthesis of more complex polymer additives and phosphite antioxidants.
• Stabilizer component for fiber and film applications requiring high clarity and color stability.

Basic Information

Product Name	3,5-Di-tert-Butyl-4-Hydroxybenzylphosphonic Acid Monoethyl Ester
CAS No.	66165-37-5
Molecular Formula	C17H29O4P
Molecular Weight	328.38 g/mol
Synonyms	Monoethyl 3,5-Di-tert-butyl-4-hydroxybenzylphosphonate; Ethyl (3,5-Di-tert-butyl-4-hydroxybenzyl)phosphonate; Irgafos 38; Antioxidant 38; Phosphonic acid, P-[(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)methyl]-, monoethyl ester; Ethanephosphonic acid, [(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)methyl]-; Bis(1,1-dimethylethyl)-4-hydroxybenzylphosphonic acid monoethyl ester
EINECS	266-207-9

Quality Control

Our production of 3,5-Di-tert-Butyl-4-Hydroxybenzylphosphonic Acid Monoethyl Ester adheres to a strict quality management system. Every batch undergoes rigorous analytical testing, including HPLC for assay and purity, to ensure it meets precise specifications for use in sensitive polymer applications. Certificates of Analysis (COA) detailing all relevant parameters are provided with each shipment and are available upon request.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at room temperature (15-25°C). This material is easily oxidized; for long-term storage, consider an inert atmosphere (nitrogen blanket). Keep away from strong oxidizing agents and heat sources.

Specification

Item	Specification
Appearance	White to off-white crystalline powder
Identification (IR)	Conforms to reference spectrum
Assay (HPLC)	≥ 98.0 %
Melting Point	73 - 78 °C
Loss on Drying	≤ 0.5 %
Heavy Metals (as Pb)	≤ 10 ppm
Phosphorus Content	9.2 - 9.6 %

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.