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Functionalization of Poly[bis(4-Methylphenoxy)Phosphazene] by free radical initiated grafting of maleic anhydride
No full textCiclofosfazeni contenenti gruppi di acido acetil salicilico, procedimento di preparazione ed utilizzazione
No full textLa presente invenzione riguarda la sintesi di derivati ciclofosfazenici contenenti sui sostituenti al fosforo gruppi di acido acetil salicilico e al loro impiego in campo farmacologico
Functionalization of phosphazenes. 1. Synthesis of phosphazene materials containing hydroxyl groups
No full textIn this paper we report the synthesis of 4-hydroxyphenol (hydroquinone)-substituted phosphazene materials, i.e., hexakis(4-hydroxyphenoxy)cyclophosphazene and poly[bis(4-hydroxyphenoxy)phosphazene], by reaction of 4-methoxyphenoxy-substituted cyclo-and polyphosphazenes with an excess of BBr3. An alternative method is based on a Pd-catalyzed hydrogenation under pressure of other phosphazene substrates bearing 4-(benzyloxy)phenoxy substituents. In the case of cyclic phosphazene derivatives, both these reactions take place very smoothly, while a dramatic decrease of the molecular weight is observed for the phosphazene high polymers during the reaction of poly[bis(4-methoxyphenoxy)phosphazene] with boron tribromide and during the hydrogenation process of the poly[bis(4-(benzyloxy)phenoxy)phosphazene]. In the case of poly[bis(4-methoxyphenoxy)phosphazene], the deblocking reaction of the methoxy group can be modulated to introduce in the phosphazene substrate a predictable amount of OH groups. The successive functionalization of the produced free hydroxyl functions in the phosphazene oligomers and polymers is also discussed by considering the acetylation of these groups as a prototype process for the phosphazene substrates. © 1992, American Chemical Society. All rights reserved
Functionalization of poly(organophosphazenes) .6. Substituent effect on the grafting reaction of maleic anhydride onto phenoxy-substituted phosphazene polymers
No full textIn this paper we describe the solution functionalization reaction of six phenoxy-substituted poly(organophosphazenes) with maleic anhydride and the effect of the phosphazene substituents on the overall grafting yield of anhydride moieties. It was found that the phosphazene polymer substituted with 4-ethylphenoxy groups is the most reactive of the whole series of exploited materials, while that bearing 4-t-butylphenoxy groups is the most inert one. This experimental reactivity trend observed in the grafting process is accounted for on the basis of both thermodynamic and steric factors
Derivati fosfazenici ciclici o polimerici contenenti gruppi ossidrilici liberi e procedimento per la loro preparazione
No full textviene presentata la sintesi di ciclo o polifosfazeni derivatizzati con sostituenti contenenti la funzione ossidrilic
Functionalization of phosphazenes.VII. Photooxidative stabilization of aryloxy-substituted poluorganophosphazenes induced by grafting HALS groups through anhydride moieties
No full textIn this article, the general procedure for stabilizing polyorganophosphazenes against the damage induced in these substrates by photooxidation reactions under accelerated conditions is explored. This method is based on the preventive grafting of succinic anhydride groups onto selected polyphosphazenes induced by light excitation, followed by the reaction of the functionalized phosphazene substrates with amino-terminated HALS groups. HALS moieties, in fact, are able to strongly inhibit the photooxidation of phosphazene films under accelerated conditions even when randomly attached to the polyphosphazene materials in very low amounts
FUNCTIONALIZATION OF POLY(ORGANOPHOSPHAZENES) .4. RADICAL-INDUCED GRAFTING OF ANHYDRIDE GROUPS ONTO POLY[BIS(4-ETHYLPHENOXY)PHOSPHAZENE]
No full textIn this paper we describe the free-radical-promoted grafting of maleic anhydride onto poly[bis(4-ethylphenoxy)phosphazene] carried out in solution under variable experimental conditions. It was found that this reaction depends on several different experimental parameters, i.e. the percentage of maleic anhydride in the system, the type and the thermal stability of the exploited peroxide initiators, the solvents used to run the grafting experiments, the amount of molecular oxygen present in the reaction medium, the heating time, and the reaction temperature. The grafting of maleic anhydride onto poly[bis(4-ethylphenoxy)phosphazene] induces profound modifications both in the physical (viscosity and glass transition temperature) and in the chemical (reactivity) properties of the phosphazene polymer and opens up unexpected perspectives to further; functionalization reactions and compatibilization processes for the phosphazene polymer
Fotoiniziatori ciclofosfazenici multifunzionali contenenti gruppi dialcossiacetofenone: sintesi e utilizzazione
No full textviene descritta la sintesi di ciclofosfazeni contenenti gruppi derivati da dialcossi acetofenone con potenziale attività di fotocatalis
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