Synthesis of DOPO-Based Phosphonamidates and their Thermal Properties

Abstract

Synthetic strategies for the preparation of 9,10-dihydro-9,10-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivatives are of special interest for polymer industry as well as academia involved in development of halogen-free flame retardant additives. In this work, various amino-DOPO derivatives (phosphonamidates) were synthesized by employing three different synthetic methods involving various chlorinating agents. The synthetic methods were compared with regards to purity and yield of the resulting amino-DOPO derivatives. The chlorinating agents that were used in this work are namely CCl 4 , trichloroisocyanuric acid and sulfuryl chloride. Some compounds, e.g., amine substituted DOPO derivative, could be synthesized using sulfuryl chloride with a yield >94% and a purity >99%. As proof of possible future industrial scale-up, up-scaling laboratory trials at the 500 g scale were also performed for two methods. The synthesized compounds were characterized for their melting point and thermal stability by using thermogravimetric analysis and direct probe insertion mass spectrometry. In general, these amino-DOPO derivatives exhibited high thermal stability with some having stability >320°C.

Multiparameter toxicity assessment of novel DOPO-derived organophosphorus flame retardants

“…The three novel compounds were designed in order to possess improved flame retardation potential, but also for a wide range of applications based on their higher melting points and increased stability, which are prerequisites for their use in the production of plastic materials (Buczko et al 2014; Gaan et al 2013, 2015; Neisius et al 2014; Salmeia and Gaan 2015; Salmeia et al 2015; Qiang et al 2011). In contrast to the current practice of investigating the potential harmful properties of flame retardants after their introduction into the market, we applied here a series of human in vitro screening assays to allow a fundamental toxicological classification before the production and application of halogen-free bis -DOPO compounds on an industrial scale.…”

“…In order to improve its flame retardation potential and influence its physico-chemical parameters, such as its melting point, to allow industrial application in different plastic materials, novel phosphonamidate and phosphonate and phosphinate derivatives of DOPO have been developed (Gaan et al 2009, 2013, 2015; Buczko et al 2014; Neisius et al 2014; Salmeia and Gaan 2015; Salmeia et al 2015), but have not been evaluated with respect to their toxicological potential. In the combustion process, phosphonamidate DOPO derivatives primarily act in the vapor phase by forming phosphorus-containing radical species (PO · ) (Salmeia and Gaan 2015; Salmeia et al 2015), which interact with · OH or H · radicals (Eq.…”

Intumescent flame retardancy of a DGEBA epoxy resin based on 5,10-dihydro-phenophosphazine-10-oxide

“…The new broad peak around 1032 cm -1 and a much higher peak at 889 cm -1 from EP-2.5 at 380 °C suggest the release of compounds containing phosphorus, 31 which may act in gas-phase flame inhibition. 33,34 In addition, the peak intensity of pyrolytic products from EP-2.5 is much larger than that from EP-0 at 380 °C, especially for hydrocarbons and aromatic compounds. However, the intensity of peaks of C=O (1766 cm -1 ), CO 2 (2383 and 2302 cm -1 ) and CO (2180 and 2108 cm -1 ) from EP-2.5 is smaller than that from EP-0 at 380 and 400 °C, indicating that the degradation process of epoxy resin matrix is changed by incorporation of DPPA.…”

Recent developments in P(O/S)–N containing flame retardants

“…28 However, regardless of the easy handling of this reaction, it has found no commercial successes as CCl 4 is a carcinogen and depletes the ozone. In these cases, P(O)─H bond has been transformed to P─Cl via the use of several chlorinating agents such as tert-butyl hypochlorite (t-BuOCl), 31 chlorine gas (Cl 2 ), 32-34 copper(II) chloride (CuCl 2 ), 35 sulfuryl chloride (SO 2 Cl 2 ), 36 n-chlorosuccinimide (NCS), 22,37 and trichloroisocyanuric acid (TCCA). In these cases, P(O)─H bond has been transformed to P─Cl via the use of several chlorinating agents such as tert-butyl hypochlorite (t-BuOCl), 31 chlorine gas (Cl 2 ), 32-34 copper(II) chloride (CuCl 2 ), 35 sulfuryl chloride (SO 2 Cl 2 ), 36 n-chlorosuccinimide (NCS), 22,37 and trichloroisocyanuric acid (TCCA).…”