Effect of the organophosphate structure on the physical and flame‐retardant properties of an epoxy resin

2‐(6‐Oxido‐6H‐dibenzo〈c,e〉〈1,2〉oxa‐phosphorin‐6‐yl)1,4‐benzenediol (ODOPB) and bis(3‐dihydroxyphenyl) phenyl phosphate (BHPP) were successfully synthesized and used as reactive flame retardants in o‐cresol formaldehyde novolac epoxy resin. Because of the rigid, cyclic, side‐chain structure of ODOPB, the resultant phosphorus‐containing epoxy resin exhibited a higher glass‐transition temperature, better flame retardancy, higher modulus, and greater thermal stability than the regular bromine‐containing tetrabromobisphenol A epoxy resin and the linear, main‐chain, phosphorus‐containing BHPP epoxy resin. A UL‐94VO rating was achieved with a phosphorus content as low as 1.1% with ODOPB (comparable to a bromine content of 12% and a phosphorus content of 2.2% with BHPP) in the cured resins, and no fumes or toxic gas emissions were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 369–378, 2002     

C‐phosphorylation of N‐arylpyrroles

Phosphorylation of N‐arylpyrroles with phosphorus tribromide proceeds regioselectively at the position 2 of the heterocyclic system. A 2‐to‐3 migration of the dibromophosphino group has been discovered, with its ease depending on the electronic nature of a substituent on the phenyl ring, solvent polarity, and the presence of pyridine hydrobromide in the reaction mixture. Further phosphorylation of 2‐ and 3‐monophosphorylated N‐arylpyrroles regioselectively involves the respective positions 4 and 5 of the heterocycle and is governed by the electron‐acceptor effect of the phosphorus‐containing substituent. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:223–228, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10012     

Phosphorus‐containing dendrimers: From material science to biology

Various methods of synthesis of phosphorus‐containing dendrimers are described. The reactivity of several of these macromolecules is then studied at several levels, mainly on the surface, and also at the level of the branches and of the core. Functionalizations confer to these macromolecules interesting properties, and allow the development of new applications, which are emphasized in this review. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:474–485, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10075     

Dipyrrolophosphinanes

The reaction of trivalent phosphorus halides with dipyrrolylmethane derivatives provides an entry to a new phosphorus‐containing heterocyclic system. Properties of the newly obtained phosphorus‐containing heterocycles have been studied. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:107–114, 2000     

Heterocondensed 1,2,3‐diazaphosphorines

The reaction of phosphorus tribromide with phenylhydrazones of heterocyclic aldehydes leads to formation of a new phosphorus‐containing heterocyclic system—heterocondensed 1,2,3‐diazaphosphorines. Properties of the phosphorus‐containing heterocyclic compounds that have been synthesized are described. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:658–664, 2001     

New Phosphorus‐Containing Quinone Derivatives II: Tri‐ and Tetraphosphorylated Quinone Derivatives

A new synthetic approach to aromatic diols substituted with two, three, and four (similar or different) phosphorus groups via the Michael‐type addition of the P H bond containing reagents to p‑benzoquinone derivatives, reoxidation, and subsequent addition of another phosphorus unit is presented. A variety of new phosphorus‐containing p‑hydroquinone derivatives were synthesized and fully characterized.     

Phospha‐Michael addition to enone‐containing triglyceride derivatives as an efficient route to flame retardant renewable thermosets

A novel phosphorus‐containing vegetable oil (PETR) was prepared through phospha‐Michael addition of a diphenyl phosphine oxide to the enone derivative of high‐oleic sunflower oil (ETR). The reaction was investigated using the enone derivative of methyl oleate under conventional thermal heating and microwave irradiation. The kinetic study showed a great enhancement of reaction rate for the microwave‐initiated addition. The crosslinking of ETR with diaminodiphenylmethane (DDM) via aza‐Michael addition was also investigated under microwave irradiation, showing a noticeable acceleration of the curing. The new phosphorus‐containing triglyceride was crosslinked with DDM to obtain phosphorus‐containing vegetable oil‐based thermosets of different phosphorus contents. Limiting oxygen index values from 26.4 to 35.0 for the final materials were obtained, demonstrating that the flame retardant properties of vegetable oil‐based thermosets can be improved by adding covalently bonded phosphorus to the polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Flame‐retardant epoxy resins from o‐cresol novolac epoxy cured with a phosphorus‐containing aralkyl novolac

A novel phosphorus‐containing aralkyl novolac (Ar‐DOPO‐N) was prepared from the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) first with terephthaldicarboxaldehyde and subsequently with phenol. The chemical structures of the synthesized compounds were characterized with Fourier transform infrared, ¹H and ³¹P NMR, and elemental analysis. Ar‐DOPO‐N blended with phenol formaldehyde novolac was used as a curing agent for o‐cresol formaldehyde novolac epoxy, resulting in cured epoxy resins with various phosphorus contents. The epoxy resins exhibited high glass‐transition temperatures (159–177 °C), good thermal stability (>320 °C), and retardation on thermal degradation rates. High char yields and high limited oxygen indices (26–32.5) were observed, indicating the resins' good flame retardance. Using a melamine‐modified phenol formaldehyde novolac to replace phenol formaldehyde novolac in the curing composition further enhanced the cured epoxy resins' glass‐transition temperatures (160–186 °C) and limited oxygen index values (28–33.5). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2329–2339, 2002     

Synthesis and properties of 4,5‐dihydrobenzo[e]imidazo[2,1‐c][1,4,2]diazaphosphinine derivatives

A number of 4,5‐dihydrobenzo[e]imidazo[2,1‐c][1,4,2]diazaphosphinine derivatives were prepared by the direct phosphorylation of 1‐(4‐Chlorophenylcarboxamido)‐2‐(1H‐1‐imidazolyl)‐5‐trifluoromethylbenzene in basic medium with phosphorus(III) bromide and dibromophenylphosphine. The tricyclic compounds 6a, 6b , and 9 having a trivalent phosphorus atom undergo the diazaphosphinine ring opening upon treatment with secondary amines in the presence of sulfur. © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:84–92, 2002; DOI 10.1002/hc.10000     

New methods of synthesis of boron,germanium, and tin derivatives of pentavalent phosphorus thioacids

The reactions of S‐trimethylsilyl esters of S‐propyl‐4‐methoxyphenyltrithiophosphonic, bis(dialkylamido)dithiophosphoric, and S‐ethyl‐diethylamidotrithiophosphoric acids with trialkyl borates, triorganylbromogermanes, trimethyl(isobutylthio)germane, and trialkylchlorostannanes were studied. On the basis of these studies, new methods of synthesizing S‐boron, S‐germyl, and S‐stannyl derivatives of pentavalent phosphorus thioacids were developed. S‐Diethylaminomethyl O‐isopropyl‐4‐ethoxyphenyldithiophosphonate was obtained by the reaction of the diisopropylboron derivative of the corresponding dithiophosphonic acid with the aminal 6 . © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:27–35, 2002; DOI 10.1002/hc.1103     

Low loss second‐order non‐linear optical crosslinked polymers based on a phosphorus‐containing maleimide

A series of crossslinked organic and organic/inorganic polymers based on maleimide chemistry have been investigated for second‐order non‐linear optical (NLO) materials with excellent thermal stability and low optical loss. Two reactive chromophores (maleimide‐containing azobenzene dye and alkoxysilane‐containing azobenzene dye) were incorporated into a phosphorus‐containing maleimide polymer, respectively. The selection of the phosphorus‐containing maleimide polymer as the polymeric matrices provides enhanced solubility and thermal stability, and excellent optical quality. Moreover, a full interpenetrating network (IPN) was formed through simultaneous addition reaction of the phosphorus‐containing maleimide, and sol‐gel process of alkoxysilane dye (ASD). Atomic force microscopy (AFM) results indicate that the inorganic networks are distributed uniformly throughout the polymer matrices on a nano‐scale. The silica particle sizes are well under 100 nm. Using in situ contact poling, the r₃₃ coefficients of 2.2–17.0 pm/V have been obtained for the optically clear phosphorus‐containing NLO materials. Excellent temporal stability (100°C) and low optical loss (0.99–1.71 dB/cm; 830 nm) were also obtained for these phosphorus‐containing materials. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and copolymerization of new phosphorus‐containing acrylates

Two phosphorus‐containing acrylate monomers were synthesized from the reaction of ethyl α‐chloromethyl acrylate and t‐butyl α‐bromomethyl acrylate with triethyl phosphite. The selective hydrolysis of the ethyl ester monomer with trimethylsilyl bromide (TMSBr) gave a phosphonic acid monomer. The attempted bulk polymerizations of the monomers at 57–60 °C with 2,2′‐azobisisobutyronitrile (AIBN) were unsuccessful; however, the monomers were copolymerized with methyl methacrylate (MMA) in bulk at 60 °C with AIBN. The resulting copolymers produced chars on burning, showing potential as flame‐retardant materials. Additionally, α‐(chloromethyl)acryloyl chloride (CMAC) was reacted with diethyl (hydroxymethyl)phosphonate to obtain a new monomer with identical ester and ether moieties. This monomer was hydrolyzed with TMSBr, homopolymerized, and copolymerized with MMA. The thermal stabilities of the copolymers increased with increasing amounts of the phosphonate monomer in the copolymers. A new route to highly reactive phosphorus‐containing acrylate monomers was developed. A new derivative of CMAC with mixed ester and ether groups was synthesized by substitution, first with diethyl (hydroxymethyl)phosphonate and then with sodium acetate. This monomer showed the highest reactivity and gave a crosslinked polymer. The incorporation of an ester group increased the rate of polymerization. The relative reactivities of the synthesized monomers in photopolymerizations were determined and compared with those of the other phosphorous‐containing acrylate monomers. Changing the monomer structure allowed control of the polymerization reactivity so that new phosphorus‐containing polymers with desirable properties could be obtained. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2207–2217, 2003     

Preparation and characterization of phosphorus‐containing Mannich‐type bases as curing agents for epoxy resin

Two novel phosphorus‐containing Mannich‐type bases, [(2‐{[(diethoxy‐phosphoryl)‐phenyl‐methyl]‐amino}‐ ethylamino)‐phenyl‐methyl]‐phosphonic acid diethyl ester (PEDA) and ({2‐[2‐(2‐{[(diethoxy‐phosphoryl)‐phenyl‐methyl]– amino}‐ethylamino)‐ethylamino]‐ethylamino}‐phenyl‐methyl)‐phosphonic acid diethyl ester (PTTA) were prepared and employed as curing agents in an attempt to prepare flame retardant epoxy systems. Through a curing reaction, phosphorus was incorporated in the backbone of the epoxy polymer. The processing characteristic of these systems was studied in terms of gel time at different temperatures. Thermal and flame retardancy properties of the cured epoxy thermosets were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and flammability test. The degradation activation energy was calculated by Kissinger's model. The results showed that the gel time of the phosphorus‐containing epoxy systems was prolonged; the glass transition temperature (T_g) was increased due to the introduction of phosphorus and the initial degradation activation energy of phosphorus‐containing epoxy systems was lower than phosphorus‐free epoxy systems. High char yield (23–27 wt%) and limiting oxygen index (LOI) values of 28–30 were observed for the phosphorus‐containing epoxy thermosets, indicating their improvement in flame retardancy. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and properties of novel phosphorus‐containing thermotropic liquid crystalline copoly(ester imide)s

A series of novel phosphorus‐containing polyesterimides were prepared from diols—a mixture of a new aromatic phosphorus‐containing bisphenol, namely 1,4‐bis[N‐(4‐hydroxyphenyl)phthalimidyl‐5‐carboxylate]‐2‐(6‐oxido‐6H‐dibenz<c,e><1,2>oxaphosphorin‐6‐yl)‐naphtalene, with aliphatic diols such as 1,3‐propanediol, 1,4‐butanediol, 1,5‐pentanediol, 1,6‐hexanediol, and 1,12‐dodecanediol—and an aromatic diacid chloride containing two preformed ester groups, namely terephthaloyl‐bis‐(4‐oxibenzoyl‐chloride), via high‐temperature polycondensation in o‐dichlorobenzene. The structures of monomers and polymers were verified by means of Fourier transform infrared (FTIR) spectroscopy and ¹H NMR spectroscopy. The molar ratio of aromatic bisphenol to aliphatic diol was varied to generate a series of copolyesterimides with tailored physicochemical properties, structure–properties relationships being established. The effect of the phosphorus content on the thermal properties and the flame retardancy was evaluated by means of thermogravimetric analysis (TGA), TGA–FTIR, and scanning electron microscopy. The polymers were stable up to 340 °C showing a 5% weight loss in the range of 340–395 °C and a 10% weight loss in the range of 370–415 °C. The char yields at 700 °C were in the range of 13.6–38% increasing with the content of phosphorus‐containing bisphenol. The effect of the aliphatic content on the liquid crystalline behavior was investigated by polarized light microscopy, differential scanning calorimetry, and X‐ray diffraction. The transition temperatures from crystal to liquid crystalline melt were in the range of 209–308 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

A New Synthetic Route to Diastereomerically Pure Cyclopropane-Phosphorus Derivatives Utilizing the Chiron 5-L-Men-thyloxy-3-bromo-2(5H)-furanone and Racemic Dialkyl α-Hydroxyalkanephosphonate

ＩｎｔｒｏｄｕｃｔｉｏｎＣｙｃｌｏｐｒｏｐａｎｅ ｃｏｎｔａｉｎｉｎｇｎａｔｕｒａｌａｎｄｎｏｎｎａｔｕｒａｌｐｒｏｄｕｃｔｓｈａｖｅｒｅｃｅｉｖｅｄｃｏｎｓｉｄｅｒａｂｌｅａｔｔｅｎｔｉｏｎａｓｓｙｎｔｈｅｔｉｃｔａｒｇｅｔｓａｓｔｈｅｉｎｃｏｒｐｏｒａｔｉｏｎｏｆｔｈｅｒｉｇｉｄｉｆｉｅｄｃｙｃｌｏｐｒｏｐｙｌｍｏｔｉｆｉｎｔｏｂｉｏａｃｔｉｖｅａｎａｌｏｇｕｅｓｌｅａｄｔｏｃｏｎｆｏｒｍａｂｌｙｃｏｎ ｓｔｒａｉｎｅｄｍｏｌｅｃｕｌｅｓ .1,2 Ｓｕｃｈｍｏｄｉｆｉｃａｔｉｏｎｓａｒｅｅｘｐｅｃ…     

New phosphorus‐containing quinone derivatives

A variety of new aromatic diols substituted with two (similar and different) phosphorus groups were synthesized via the Michael‐type addition of a P H bond containing reagents to p‐benzoquinone, reoxidation and the subsequent addition of a second phosphorus unit. In all studied cases, 2,3‐substituted products were obtained exclusively. The resulting hydroquinone derivatives were further investigated regarding rearrangements under basic conditions. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:383–394, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21028     

C‐phosphorylation of 1,2,4‐triazoles with phosphorus(III) halides. Synthesis of 4,5‐dihydrobenzo[e][1,2,4]triazolo[5,1‐c][1,4,2]diazaphosphinine derivatives

Phosphorylation of 4‐ and 1‐substituted 1,2,4‐triazoles with PCl₃, PhPCl₂, Ph₂PCl, and (Et₂N)₂ PCl was carried out. A novel phosphorus‐containing condensed heterocyclic system ( 18, 23 ) was constructed by the reactions of 2‐(1H‐1,2,4‐triazol‐1‐yl)‐1‐(4‐chlorophenylcarboxamido)‐5‐trifluoromethylbenzene with PBr₃ and PhPBr₂. Treatment of the bromophosphonite 18 with an excess of morpholine in the presence of sulfur resulted in a diazaphosphinine ring opening and provided functionalized 1H‐1,2,4‐triazol‐5‐ylphosphonic acid derivatives 21 and 22 . © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:146–152, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10010     

Epoxy resins from novel monomers with a bis‐(9,10‐dihydro‐9‐oxa‐10‐oxide‐10‐phosphaphenanthrene‐10‐yl‐) substituent

A new diepoxide and a new diamine, both bearing bis‐(9,10‐dihydro‐9‐oxa‐10‐oxide‐10‐phosphaphenanthrene‐10‐yl‐)‐substituted methylene linkages, were prepared through the reaction of 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide with benzophenone derivatives via a simple addition reaction followed by a dehydration reaction. These two compounds were used as monomers for preparing cured epoxy resins with high phosphorus contents. The resultant epoxy resins showed high glass‐transition temperatures (between 131 and 196 °C). All of the cured epoxy resins exhibited high thermal stability, with 5% weight loss temperatures over 316 °C, and excellent flame retardancy, with limited oxygen index values of 37–50. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 359–368, 2002     

Synthesis of poly(oxyethylene phosphoramidate)s and glycopolymers via Staudinger reaction: Multivalent binding studies with Concanavalin A

A new method for the preparation of poly(oxyethylene phosphoramidate)s and glycopolymers is developed via modification of poly(oxyethylene H‐phosphonate) which is a biodegradable, biocompatible and low toxic polymer. The phosphonate groups of the precursor are converted into tri‐coordinated phosphorus species yielding poly(oxyethylene trimethylsilyl phosphite). The latter is then reacted with different azides, including sugar azides, via Staudinger reaction to furnish the desired poly(oxyethylene phosphoramidate)s and such containing sugar moieties in the side chains attached to the P‐centers. 2002P NMR spectroscopy is applied as a powerful tool for determination of the conversion and structure of the reaction products. Studies on Concanavalin A binding to the obtained glycopolymers are performed using dynamic light scattering and analytical ultracentrifugation techniques. The viability of Human Embryonic Kidney 293 cell line is slightly affected when exposed to polyphosphoramidate glucoconjugate over a broad range of concentrations. The results obtained are encouraging for further investigations on the clustering and bio‐recognition properties of the synthesized glycopolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1730–1741     

Oligosilane‐ and Oligosiloxane‐bridged Phosphines – Synthesis,Structures, and Metalation

The range of molecular silicon phosphorus compounds has been extended by some new species containing oligosilane ((R₂Si)_n; n ≥ 2) or oligosiloxane ((R₂SiO)_mSiR₂; m ≥ 1) fragments bound to phosphorus atoms. Primary and secondary compounds of these types allow for the synthesis of metal derivatives. Such metalated species usually form oligomers and exhibit a versatile structural chemistry with cyclic, polycyclic, and cage‐like patterns. The main results obtained in the field of oligosilane‐ and oligosiloxane‐bridged phosphines will be presented below and the structures of the metal derivatives will be discussed. Moreover, the synthesis of an inorganic ligand on the basis of siloxane‐bridged phosphines will be presented. This compound opens up a new chapter in host‐guest chemistry.