Diethyl phosphite

Diethyl phosphite (CAS 762-04-9), also referred to commercially as diethyl phosphonate or DEP, is a reactive organophosphorus compound used as a chemical intermediate and functional additive across multiple industrial sectors. It acts as a building block for synthesizing phosphorus-containing compounds and delivers antioxidant, stabilizing, and lubrication functions in finished formulations. In lubricant and metalworking fluid formulations, DEP functions as an extreme-pressure additive.

It serves as an antiwear agent, reducing metal surface degradation under high-load conditions. Pharmaceutical manufacturers use it as a key intermediate in the synthesis of active pharmaceutical ingredients, particularly antiviral and antiparasitic compounds. In agrochemical production, it serves as a precursor in the manufacture of organophosphate pesticides and herbicides. Polymer and plastics processors incorporate DEP as a flame retardant additive and stabilizer.

This helps to meet flammability and thermal performance requirements in end products. Diethyl phosphite is supplied as a clear, colorless to pale yellow liquid in drum and IBC quantities, with bulk tanker supply available. Technical grade is the standard commercial offering, with purity levels typically at 98% or higher. Pharmaceutical-intermediate-grade material with controlled impurity profiles is available from select manufacturers.

This material is designed to support API synthesis qualification requirements. The product is handled according to strict industrial safety protocols to ensure consistent quality and performance across all applications.