Synthesis and fire extinguish performance of a ferrocene derivative with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)

To explore novel substances that could potentially replace conventional fire extinguishing agents, the author designed and synthesized a new compound, Fec-DOPO, which incorporates both ferrocene and the well-known flame retardant moiety 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The synthesis of Fec-DOPO proceeded with a moderate yield of 45.3%, and the chemical structure was rigorously confirmed using X-ray diffraction analysis. The fire extinguishing performance of the compound was evaluated using a filter paper test, where a suppressant was applied to finely cut filter paper and then burned. The results revealed that Fec-DOPO exhibited a lower flame retardant effect than its individual components, ferrocene and DOPO. To gain insight into the underlying mechanism, thermogravimetric analysis was performed, demonstrating that cyclopentadiene, which acts as a ligand in the ferrocene unit, was released upon heating. This observation suggests that the partial thermal decomposition of Fec-DOPO may be responsible for its reduced ability to extinguish fire. Overall, these results indicate that while Fec-DOPO represents a promising hybrid structure combining ferrocene and DOPO, further optimization of its thermal stability may be required to achieve an effective fire extinguishing performance comparable to existing agents.