DOPO Flame Retardant

DOPO Flame Retardant

Phosphaphenanthrene (DOPO) and its derivatives, as novel phosphorus-containing flame retardants, exhibit excellent thermal stability and flame retardant properties compared to other flame retardants. Alfa Chemistry provides customers with a range of DOPO and its derivatives flame retardants.


Phosphophenanthrene cyclic phosphates are organophosphorus heterocyclic compounds. With high thermal stability, oxidation resistance and excellent water resistance, it is a reactive and additive flame retardant. Because the flame retardant has P-C bonds, the flame retardant performance is better than that of ordinary phosphate esters.


  • Used for polyester fibers, polyurethane foams, thermosetting resins and adhesives.
  • Used as flame retardant for plastics, copper lining laminates, circuit boards and other materials for electronic equipment.
  • Used for ABS, flexible polyurethanes, epoxy resins, unsaturated polyester resins, phenolic resins, coatings, textiles.
  • Used as a color preventer. It is used to prevent coloring, such as ABS, AS, PP, PS, epoxy resin, phenolic resin, alkyd resin, coloring caused by surfactant, and coloring caused by light and heat of polyurethane.
  • Used for the synthesis of new flame retardants. DOPO contains active O=P-H bonds, and has high addition activity to alkenyl, epoxy bonds and carbonyl groups. It can react to generate various derivatives, and at the same time form synergistic flame retardant with nitrogen, silicon and other elements to improve the flame retardant effect.

Synthesis of DOPO Derivatives

Due to the toxicity and environmental concerns of halogenated flame retardants, phosphorus-containing flame retardants have attracted much attention as environmentally friendly alternatives. Alfa Chemistry is dedicated to the synthesis of DOPO-based organophosphorus compounds and their application as flame retardants. If you do not find a DOPO based flame retardant that interests you in the product list, feel free to contact us to discuss your specific synthesis needs.

Examples of synthetic routes Examples of synthetic routes

Research Information

Double DOPO structure

Yuzhong Wang's team designed and synthesized a novel reactive phosphorus-containing flame retardant (TDCAA-DOPO) with two symmetrical synthetic DOPO structures (Bi-DOPO). In this work, the researchers investigated the thermal stability and flammability of Bi-DOPO and crosslinking to unsaturated polyesters. The results show that the reactive TDCAA-DOPO endows FR-UPR with higher thermal stability, residual coke and glass transition temperature (Tg). [1]

Synthetic route of TDCAA-DOPO and its curing reaction with UPR resinSynthetic route of TDCAA-DOPO and its curing reaction with UPR resin [1]

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  1. Yuan Cao, et al. (2017), "Bi-DOPO Structure Flame Retardants with or without Reactive Group: Their Effects on Thermal Stability and Flammability of Unsaturated Polyester," Ind. Eng. Chem. Res. 56(20), 5913–5924.
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