Flame-Resistant Polymers. Polyphos-phates and Polyphosphonates from Di-hydroxy Compounds

Coover, H. W.; McConnell, Richard L.; McCall, M. A.

doi:10.1021/ie50605a030

Cited by 32 publications

(11 citation statements)

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“…12 The literature describes two basic routes for their preparation. One involves the condensation of methylphosphonic dichloride with the appropriately substituted phenol.…”

Section: Methodsmentioning

confidence: 99%

New Feature of Friedel-Crafts Phosphonation of Anisoles: Unexpected In Situ Methylphosphorylation Reaction

Baccolini¹,

Boga²

1999

Synlett

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Anisoles 1, reacting with AlCl 3 and PCl 3 with appropriate reagent ratios, give, in good yields, the corresponding diaryl methylphosphonates 2 or the methylphoshinates 3b,c and the methylphosphine oxides 4b,c. This unexpected in situ methylphosphorylation explains the reported limited and conflicting results to obtain methoxy-substituted arylphosphonous dichloride with the same reagents. A suggested mechanism is also reported.Since the last century, the Friedel-Crafts-type reaction 1 using PCl 3 and AlCl 3 has been of interest for the direct phosphonation of an aromatic ring. However, this reaction is very sensitive to the type of substituents present on the aromatic ring. 2 In particular, very limited success and conflicting results have been reported when the reaction is carried out with anisoles. For example, anisole, 3,4 upon treatment with PCl 3 and AlCl 3 gave complex reaction mixtures depending on the quality of AlCl 3 with poor yields of methoxy-substituted arylphosphonous dichloride or phenylphosphorodichloridite and large amounts of undistillable residues:To increase the yield and the selectivity of this phosphonation reaction the use 4a of SnCl 4 and very recently the use 4c of BiCl 3 have been reported. In the past years we discovered 5 an unusual reaction of PCl 3 and AlCl 3 with thioanisoles which gave a new heterocyclic system (fused 1,2,3-benzothiadiphosphole) containing the P-PS 2 unit. Recently, the course of this unexpected diphosphonation reaction has been studied 6 and we have found that the reaction follows a complex multistep pathway which was a priori unpredictable and that the outcome of the reaction is very dependent on the ratio of the reagents and on the good quality of AlCl 3 (sublimated prior to use) which in this reaction is a true reagent and not a catalyst.Then, we thought to study again the reaction of anisoles 1 with AlCl 3 and PCl 3 , in order to find results which might explain the reported 3,4 formation of large amounts of undistillable residues. Several reactions were carried out with various molar proportions of reagents and different reaction conditions. The reaction of 1b with an appropriate ratio of the reagents, afforded a mixture containing as major products the corresponding diaryl methylphosphoryl derivatives 2b, 3b and 4b arising from an unexpected in situ methylphosphorylation (Scheme1). Scheme 1After several repeated attempts with small variations of reagent ratios and reaction conditions we could control the regiochemistry of this methylphosphorylation reaction in order to obtain mainly the diaryl methylphosphonates 2 (see Scheme 1). The best results were obtained with a 1: AlCl 3 : PCl 3 ratio of 1:0.6:1, at 70-80°C in atmosphere of dry nitrogen and without solvent (Table 1). In the case of 1c the reaction was complete in 7 h while in the other cases in about 10-15 h. A stoichiometric excess of PCl 3 was useful also to ease the stirring and the homogeneity of the reaction mixture. Compounds 2 have been fully characterised 7 by 1 H and 31 P NMR and spectral data...

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“…12 The literature describes two basic routes for their preparation. One involves the condensation of methylphosphonic dichloride with the appropriately substituted phenol.…”

Section: Methodsmentioning

confidence: 99%

New Feature of Friedel-Crafts Phosphonation of Anisoles: Unexpected In Situ Methylphosphorylation Reaction

Baccolini¹,

Boga²

1999

Synlett

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“…[16][17][18][19][20] Several reaction conditions have been reported to prepare polymers for applications in lubricants, optics, medicine and, most importantly, as flame-retardant additives. [21][22][23][24][25][26] In order to widen the horizon for future applications in the biomedical field, our group has reported the controlled synthesis of highly water-soluble poly(phosphonate)s via AROP, 27 ring-opening metathesis polymerization (ROMP) and ADMET polymerization. ADMET of acyclic unsaturated phosphonates yields hydrophobic materials that show similar bone-targeting properties as their phosphate counterparts.…”

Section: Introductionmentioning

confidence: 99%

Poly(phosphonate)-mediated Horner–Wadsworth–Emmons reactions

2015

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A novel, general protocol for a polymer-mediated Horner-Wadsworth-Emmons (HWE) reaction is reported. The polyvalent polymeric reagent was prepared via acyclic diene metathesis (ADMET) polymerization. Homo-and copolymers of reactive poly(phosphonate)s with molecular weights up to 40 000 g·mol −1 and molecular weight dispersities Ð < 2 were successfully synthesized. Subsequent application of these polymers in the HWE reaction to prepare a library of aromatic α,β-unsaturated ketones (chalcons) has proven to be an efficient synthetic pathway to minimize purification efforts, as the polymeric side-product can be removed by simple precipitation. In this paper we also demonstrate for the first time the preparation of a linear polyphosphate from a polyalkylphosphonate.Scheme 1 General scheme for the HWE reaction (R 1 = alkyl, phenyl; R 2 = electron withdrawing group; R 3 = alkyl, phenyl, R 4 = H, alkyl). † Electronic supplementary information (ESI) available. See

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“…Various researchers have used this approach to produce linear high molecular weight polyphosphates. 5,6 It has been noted, however, that bulk polymerization requires a high temperature to melt all the reactants and frequently leads to side products that limit the molecular weight and increase the polydispersity (PD) of the final polymer. 7 Such side reactions are especially not desirable in biomedical applications, wherein polymers with high purity and well-characterized chemical structures are both desired and required.…”

Section: Introductionmentioning

confidence: 99%

“…Bulk polycondensation is often used as a preferred route for large‐scale production of high molecular weight polymers because of its apparent advantages such as short reaction times, minimal purification steps, and feasibility for scale‐up. Various researchers have used this approach to produce linear high molecular weight polyphosphates 5, 6. It has been noted, however, that bulk polymerization requires a high temperature to melt all the reactants and frequently leads to side products that limit the molecular weight and increase the polydispersity (PD) of the final polymer 7.…”

Section: Introductionmentioning

confidence: 99%

Compositional analysis of biodegradable polyphosphoester copolymers using nmr spectroscopic methods

Chaubal¹,

Wang²,

Su³

et al. 2003

J of Applied Polymer Sci

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ABSTRACT:The chemical composition and quantitative molar ratios among all components of biodegradable polyphosphoester copolymers of dl-lactide and ethylphosphate were determined by a comprehensive set of NMR spectroscopic methods. The polyphosphoester copolymers studied were synthesized using condensation polymerization of oligomeric dl-lactide prepolymers and ethyl dichlorophosphate. Conclusive identification of the chemical shift patterns of all functional groups in the copolymers required additional NMR methods such as 31 P-NMR and two-dimensional 1 H-1 H COSY NMR, in addition to the synthesis and comparative NMR analysis of model compounds possessing identical phosphoester linkages in the polyphosphoester copolymers. For the polymers synthesized using the bulk polycondensation process, 1 H-1 H COSY NMR analysis revealed the presence of a small amount of side products that were undetected by 1 H-NMR alone. These side reactions most likely occurred between the pendant ethoxy group of the phosphoesters and the hydrogen chloride gas generated in the bulk polycondensation process.31 P-NMR spectra of the copolymers revealed a consistent triple-peak pattern characteristic of phosphoesters linked to a racemic mixture of d,l-lactides. These results offered new insight into the side reactions occurring in bulk polymerization of polyphosphoesters and provided a powerful tool of characterizing complex biodegradable polymers.

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Flame-Resistant Polymers. Polyphos-phates and Polyphosphonates from Di-hydroxy Compounds

Cited by 32 publications

References 1 publication

New Feature of Friedel-Crafts Phosphonation of Anisoles: Unexpected In Situ Methylphosphorylation Reaction

New Feature of Friedel-Crafts Phosphonation of Anisoles: Unexpected In Situ Methylphosphorylation Reaction

Poly(phosphonate)-mediated Horner–Wadsworth–Emmons reactions

Compositional analysis of biodegradable polyphosphoester copolymers using nmr spectroscopic methods

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