A halogen-free flame retardant containing nitrogen and phosphorus, 2-[anilino-(6-oxobenzo[c][2,1]benzoxaphosphinin-6-yl)methyl]phenol (PDOP), has been synthesized by reaction of benzo[c][2,1]benzoxaphosphinine-6-oxide (DOPO) with 2-( N-phenyliminomethyl)phenol. Halogen-free flame-retardant rigid polyurethane foams (RPUF-PDOP) were prepared using PDOP as a flame retardant. The flammability was investigated using limiting oxygen index, a vertical burning test (UL-94), and a cone calorimeter. When PDOP (10 wt%) as flame retardant was added to RPUF (RPUF-PDOP10%), the limiting oxygen index value was increased from 18% to 27%, and a UL-94 V-0 rating was achieved; meanwhile, the peak heat release rate, total heat release, and the average mass-loss rates of RPUF-PDOP10% were reduced from 246 to 207 kW m−2, from 26.9 to 21.0 MJ/m2, and from 0.043 to 0.033 g/s, respectively. Especially, the initial decomposition temperature of RPUF-PDOP10% was decreased from 228°C to 209°C. The final residual char from decomposition of RPUF-PDOP10% was significantly increased up to 35.6%. The addition of PDOP did not markedly decrease the mechanical properties of the resulting flame-retardant RPUFs.

Summary A novel bio‐based P‐N containing intumescent flame retardant melamine starch phytate (PSTM) was prepared via the reaction of phytic acid starch ester with melamine and characterized by Fourier transform infrared, scanning electron microscopy and thermogravimetric analysis (TGA). The effects of PSTM on thermal properties and flammability of rigid polyurethane (PU) foams were analyzed by TGA, limit oxygen index (LOI), vertical burning tests (UL‐94) and cone calorimeter measurement. The TGA results demonstrated that the thermal stabilities of PU/PSTM foam at high temperature was enhanced with the increasing additive amount of PSTM. The results showed that PU foam with 30 php PSTM (PU/PSTM‐30%) observed an LOI value of 25.9 and a UL‐94 rating of V‐0. Cone calorimetry data showed that peak heat release rate, total heat release and smoke production rate of PU/PSTM‐30% were distinctly lower than that of pure PU. Further experimental results demonstrated that PSTM promotes well charring of PU which could protect the foam from combustion. This work developed a novel bio‐based intumescent flame retardant by suing phytic acid and starch as the acid source and carbon source, respectively, which is of great significance to the preparation of environmental‐friendly flame retardants.

A series of bis(phenol)-functionalized imidazolium salts, 1,3-bis(4,6-di-R(1)-2-hydroxybenzyl)-2-R(2)-4,5-di-R(3)-imidazolium chlorides H(3)L(n)Cl (R(1) = (t)Bu, R(2) = R(3) = H, H(3)L(1)Cl, 1; R(1) = CH(3), R(2) = R(3) = H, H(3)L(2)Cl, 2; R(1) = (t)Bu, R(2) = H, R(3) = Cl, H(3)L(3)Cl, 3; R(1) = (t)Bu, R(2) = CH(3), R(3) = H, H(3)L(4)Cl, 4), were used to produce a novel series of ionic iron(III) complexes [H(3)L(n)][FeX(4)] (n = 1, X = Cl, 5; n = 2, X = Cl, 6; n = 3, X = Cl, 7; n = 4, X = Cl, 8; n = 1, X = Br, 9; n = 3, X = Br, 10). All of the complexes were characterized by Raman spectroscopy and electrospray ionization mass spectrometry. Elemental analysis and X-ray crystallography were also used. All of the complexes were non-hygroscopic and air-stable, with five of them existing as solids (5, 7-10) and one as an oil (6) at room temperature. A preliminary catalytic study on the cross-coupling reactions of aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens, revealed that all of the ionic iron(III) complexes exhibited good to excellent catalytic activity. Complexes 5, 6 and 8 exhibited optimal activity, whereas 7, 9 and 10 showed only moderate activity. Furthermore, by simply decanting the cross-coupling product in the ether layer, complexes 5 and 6 could be reused in at least seven successive runs without significant loss in catalytic activity.

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A flame retardant with enhanced phosphorus−nitrogen content, 5,5-dimethyl-2-(phenyl(phenylamino)methyl)-1,3,2-dioxaphosphinane 2-oxide (DPPO), was synthesized by the reaction of 5,5-dimethyl-1,3,2-dioxaphosphinane 2-oxide (DDPO) with N-benzylideneaniline. The structure of DPPO was characterized by nuclear magnetic resonance ( 1 H NMR and 31 P NMR) and Fourier transform infrared (FT-IR) spectroscopy. The thermal stability of DPPO was characterized by thermogravimetric analysis (TGA). The solubilities of DPPO were measured in different solvents including ethyl acetate, methanol, chloroform, acetonitrile, acetone, 1,2dichloroethane, 1,4-dioxane, dichloromethane, tetrachloromethane, benzene, tetrahydrofuran, and isopropanol at temperature ranging from 278.15 to 347.15 K by the gravimetrical method. The mole fraction solubilities of DPPO in the above-mentioned organic solvents were correlated as the Apelblat equation, and the calculated values with equations shows good consistency with the experimental values. The root-mean-square deviation was less than 0.1%, and the average relative error was less than 0.04 in all of the experiments.