Synthesis and Chemical Regularity in Phosphazene Copolymers

Carriedo, Gabino A.

doi:10.1002/9780470478882.ch19

Cited by 4 publications

(8 citation statements)

References 70 publications

(73 reference statements)

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“…8 The process consisted on a nitration-reduction protocol to obtain the corresponding polyaminophosphazene derivative which was subsequently activated with glutaraldehyde and then reacted with the enzyme solution. Later, an invertase was supported on spherical particles of [NP(OCH 2 CF 3 ) 2 ] n , first displacing the trifluoroethoxy moieties with NaOCH 2 CH 2 NH 2 and then anchoring the enzyme, obtaining good activities for this preparation. 9 Finally, an urease was encapsulated on a hydrogel derived from poli[bis(methoxyethoxyethoxy)phosphazene] through irradiation with γ-rays to cross the polymer and trap the biocatalyst.…”

Section: Introductionmentioning

confidence: 99%

“…19 Recently, the regioselective and controlled direct nitration of the homopolymer [NP(O 2 C 12 H 8 )] n (1), which is readily available, 20 was achieved by taking advantage of the unusual high solubility and stability of this precursor in concentrated sulfuric acid, to obtain in one pot simple procedure the derivatives {NP[O 2 C 12 H 8-x (NO 2 ) x ]} n (2) with x ranging from 0.2 to 2 in excellent yields (Scheme 1). 21 As polymers 2, with M w of the order of 10 5 , are well characterized materials (by 1 H, 13 C, 31 P, and IR spectra) with well defined chemical composition and with limited but sufficient solubility in THF, 21 (3), useful to support enzymes. Herein we wish to report the use of 3 to immobilize an alcohol dehydrogenase (ADH-'A') for bioreductions on aqueous solutions, and a lipase (CAL-B) to achieve kinetic resolutions on organic solvents.…”

Section: Introductionmentioning

confidence: 99%

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Polyphosphazenes as Tunable and Recyclable Supports To Immobilize Alcohol Dehydrogenases and Lipases: Synthesis, Catalytic Activity, and Recycling Efficiency

et al. 2010

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Abstract.The polyphosphazene {NP[O 2 C 12 H 7.5 (NH 2 ) 0.5 ]} n , prepared by reacting {NP[O 2 C 12 H 7.5 (NO 2 ) 0.5 ]} with the Lalancette's reagent, was used for attaching enzymes such as alcohol dehydrogenase (ADH-'A') and lipase (CAL-B). The resulting new biocatalysts exhibited great potential as tunable supports for enzymatic reactions in both aqueous and organic media. The material with immobilized ADH-'A' was as efficient as the commercial enzyme to perform stereoselective bioreductions of ketones in aqueous solutions and could be used for the reduction of various aliphatic and aromatic ketones up to 60ºC and recycled several times without significant loss of activity even after three months of storage. The biocatalyst obtained with CAL-B was more efficient than the free enzyme for kinetic resolutions in organic solvents and exhibited a moderately good capability of reutilization.2

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polyphosphazenes as Tunable and Recyclable Supports To Immobilize Alcohol Dehydrogenases and Lipases: Synthesis, Catalytic Activity, and Recycling Efficiency

et al. 2010

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“…9 Other examples of chemical modification of pendant groups as a route to functionalized polyphosphazenes can be found in the literature. 10 However, only a few attempts have been made to halogenate aromatic substituents in polyphosphazenes, such as the bromination with N-bromosuccinimide of methylphenoxy groups that gave the bromomethyl derivatives without affecting the arene ring. 3b In fact, the synthesis of halophenoxy derivatives has been achieved by introducing halophenoxide nucleophiles by macromolecular substitution.…”

Section: Introductionmentioning

confidence: 99%

Chlorination, Iodination, and Silylation of Poly(2,2′-dioxy-1,1′-biphenylphosphazene). New Halogenated Polyphosphazenes with Sterically Hindered Reactivity

Carriedo

Valenzuela

2009

Macromolecules

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The polyphosphazene {[NP(O2C12H8)]} n (1) [(O2C12H8) = 2,2′-dioxy-1,1′-biphenyl] with [PO2C12H8] cycles in the repeating units reacts slowly with chlorine in concentrated sulfuric acid to give the 5,5′-chlorinated {[NP(O2C12H8)]1−x [NP(O2C12H7Cl)] x } n (2) (x = 0.2−1), with limiting oxygen index (LOI) in the interval 26−33 (estimated from the TGA residues), corresponding to potential self-extinguishing flame retardants. The reaction of 1 with [Ipy2]BF4 in CH2Cl2 in the presence of CF3SO3H gave the 5,5′-iodinated {[NP(O2C12H8)]1−x [NP(O2C12H7I)] x } n (3) (x = 0.2−1) which, in contrast, are thermally unstable, leaving almost no TGA residues. The potential of 2 and 3 as precursors for the chemical derivation of 1 was assessed by the silylation method (reaction with LiBu t at −78 °C followed by addition of ClSiMe3 and a complete characterization of the resulting trimethylsilyl derivatives). The isolation of polymers {[NP(O2C12H8)]0.65[NP(O2C12H7Cl)]0.15[NP(O2C12H7SiMe3)]0.2} n (4) and {[NP(O2C12H8)]0.8[NP(O2C12H7SiMe3)]0.2} n (5) demonstrated that the lithiation was 40−50% efficient with the chlorine derivatives and approached 100% with the iodine analogues. The silylation of the available Li sites was less effective with the higher lithiated polymers and always below the levels usually observed. The reactivity of polyphosphazenes with 2,2′-dioxy-1,1′-biphenylphosphorus repeating units is therefore limited by steric and conformational effects reinforced by the proximity of the reaction centers to the main chain.

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“…Most polyphosphazenes are actually copolymers, and recently attention has been paid to achieve well-defined two substituent polyphosphazenes [NPA 2− x B x ] n with a high degree of chemical regularity . A significant part of these polyphosphazenes are random copolymers obtained by the so-called macromolecular substitution from the linear soluble [NPCl 2 ] n (Scheme ), using various proportions of two different nucleophiles (sequential macromolecular substitution).…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on the Mechanism and Regioselectivity of the Macromolecular Substitution Reactions of [NPCl₂]_n with Bifunctional Nucleophiles by a Combination of Quantum Mechanical and Molecular Dynamics Calculations

et al. 2009

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A combination of molecular dynamics simulations and quantum chemistry calculations affords a good understanding of the reaction between [NPCl2] n and the bifunctional nucleophile aminophenol HO−C6H4−NH2 in THF solution and in the presence of alkali carbonates. This reaction is regiospecific at room temperature favoring the attack by the NH2 group, and only at higher temperatures the attack by the OH is activated. It is also explained why the reaction of HO−C6H4−NH2 with {[NP(O2C12H8)]1−x [NPCl2] x } n and Cs2CO3 at reflux proceeds exclusively by the OH giving aryloxyphosphazenes with terminal NH2 substituents. Molecular dynamics simulations have been performed on model systems consisting on [NPCl2] n chains surrounded by aminophenol molecules or ions obtained by deprotonation of either the OH or NH2 groups. Quantum mechanics calculations consisted in density functional theory (DFT) computation of the reaction mechanism of aminophenol with the phosphoranimine (NH2)Cl2P(=NH) as a simple model for the NPCl2 phosphazene units, using B3LYP approximation with 6-31G(d). Our results provide evidence to support that the macromolecular substitution reactions of poly(dichlorophosphazene) with aryloxide ions are diffusion controlled and governed by the atomic charges, while the reaction with amino-arenes are directed by hydrogen interactions between the NH2 hydrogens and the phosphazene nitrogen atoms that initiate a lower activation energy stepwise mechanism competing with a concerted mechanism. The combined methodology employed in this work seems to be useful to address the regiochemistry of the macromolecular substitution on polyphosphazenes with heterobifunctional nucleophiles which is a central issue in the design of polymers with predetermined chemical composition and structure.

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Synthesis and Chemical Regularity in Phosphazene Copolymers

Cited by 4 publications

References 70 publications

Polyphosphazenes as Tunable and Recyclable Supports To Immobilize Alcohol Dehydrogenases and Lipases: Synthesis, Catalytic Activity, and Recycling Efficiency

Polyphosphazenes as Tunable and Recyclable Supports To Immobilize Alcohol Dehydrogenases and Lipases: Synthesis, Catalytic Activity, and Recycling Efficiency

Chlorination, Iodination, and Silylation of Poly(2,2′-dioxy-1,1′-biphenylphosphazene). New Halogenated Polyphosphazenes with Sterically Hindered Reactivity

Theoretical Study on the Mechanism and Regioselectivity of the Macromolecular Substitution Reactions of [NPCl₂]_n with Bifunctional Nucleophiles by a Combination of Quantum Mechanical and Molecular Dynamics Calculations

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Synthesis and Chemical Regularity in Phosphazene Copolymers

Cited by 4 publications

References 70 publications

Polyphosphazenes as Tunable and Recyclable Supports To Immobilize Alcohol Dehydrogenases and Lipases: Synthesis, Catalytic Activity, and Recycling Efficiency

Polyphosphazenes as Tunable and Recyclable Supports To Immobilize Alcohol Dehydrogenases and Lipases: Synthesis, Catalytic Activity, and Recycling Efficiency

Chlorination, Iodination, and Silylation of Poly(2,2′-dioxy-1,1′-biphenylphosphazene). New Halogenated Polyphosphazenes with Sterically Hindered Reactivity

Theoretical Study on the Mechanism and Regioselectivity of the Macromolecular Substitution Reactions of [NPCl2]n with Bifunctional Nucleophiles by a Combination of Quantum Mechanical and Molecular Dynamics Calculations

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Theoretical Study on the Mechanism and Regioselectivity of the Macromolecular Substitution Reactions of [NPCl₂]_n with Bifunctional Nucleophiles by a Combination of Quantum Mechanical and Molecular Dynamics Calculations