41 / 2023-08-12 16:27:18

Green synthesis and application of novel organophosphorous flame retardant

Green synthesis; organophosphorous flame retardant; photosynthesis; DOPO

Phosphorus Material Chemistry and Applied Science > 1) Phosphorus chemistry in material science

Fire safety research of high-performance polymer materials has emerged as a cutting-edge international topic. Organic phosphorus flame retardants have garnered widespread attention due to their efficient and environmentally friendly attributes. However, existing phosphorus-containing flame retardants still face limitations in terms of structural diversity, complex synthesis, and high costs, hindering their industrial application. In this study, we embark on a journey of structural design, harnessing the power of green technologies such as photochemistry, to synthesize a diverse range of novel organic phosphorus flame retardants in a single step. Initially, employing dibenzo[b,f][1,4]oxa/thiazepine as a precursor and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as a phosphorus source, a series of DOPO derivatives are obtained via a one-pot nucleophilic addition. Notably, by modulating the oxygen and sulfur atoms within the dibenzo[b,f][1,4]zepine framework, it becomes possible to tailor the dielectric and transparency properties of flame-retardant epoxy resins. Such materials hold great promise for advanced electronic encapsulation^[1]. Furthermore, utilizing benzocyclic imines and P(O)H as substrates, we employ photochemistry and continuous flow techniques to develop a cross-dehydrogenative coupling reaction, enabling modular and scalable synthesis of novel phosphonylated benzozepines derivatives. Taking benzo[d]thiazol-2-yldiphenylphosphine oxide as an example, a mere 2 wt% loading achieves a UL-94 V-0 rating for epoxy resin, showcasing exceptional flame-retardant performance^[2]. In summary, we have devised green synthesis methodologies for a series of structurally novel phosphorus-containing flame retardants, successfully applying them to the fabrication of flame-retardant high-performance polymer materials.