Polyphosphonates synthesis

Polyphosphonates are well-known flame-retardant materials [110] and are generally prepared by melt [111,112], interfacial [113-115] and solution polycondensation methods [116]. A typical example of synthesis is the polycondensation of bifunctional organophosphorus compounds, such as dichlorophenylphosphine oxide, with bisphenols [117,118]. 

Some alternative syntheses use malic acid, urea, and PPA (61 SCI 1923) or maleic/fumaric acid, urea, and polyphosphonic acid (PPA) (71S154). The reaction of formylacetate with thiourea is convenient for the synthesis of 2-thiouracil (08JA547 10JA19). Another main synthesis involves the... 

Apart from their behaviour as ligands in metal catalyst systems, studies of the reactivity of phosphites towards a wide variety of other substrates have attracted attention. New aspects and applications of the classical Michaelis-Arbuzov reaction and its variants continue to appear. Evidence of the thermal disproportionation of methyltriaryloxyphosphonium halides formed in the reactions of triarylphosphites with alkyl halides, together with the formation of P-O-P intermediates, has been reported. The Michaelis-Arbuzov reaction has been used in the synthesis of phosphonate-based styrene-divinylbenzene resins and polyphosphonated chelation therapy ligands.Treatment of electron-rich benzylic alcohols dissolved in triethylphosphite with one equivalent of iodine affords a low-temperature one-pot route to the related benzylic phosphonates, compounds which are otherwise difficult to prepare. Upper-rim chloromethylated thiacalix[4]arenes have also been shown to undergo phosphonation on treatment with a phosphite ester in chloroform at room temperature. The nickel(II)-catalysed reaction of aryl halides with phosphite esters in high boiling solvents, e.g., diphenyl ether, (the Tavs reaction), has also... 

This is an area in which the syntheses of functionalized acids (as their esters) has predominated (Chapter 3, Sections VI and VII). Nevertheless, the procedure is not without its uses in non-functionalized systems, and it has also received attention as a means for the synthesis of polyphosphonic acids (as their esters). 

The earliest report on the nonbiological s tithesis of polyphosphonates and polyphosphate ester was by Arvin. (Arvin, 1936). Much of the earlier work in the synthesis of polyphosphate ester was carried out by Millich et al, (Millich, 1969, 1974). One of the earliest re iews in the interfacial s)tithesis of polyphosphonates, polyphosphates and polyphosphites by Millich et al, (Millich, 1977) is highly recommended. 

Interfacial poly condensations for the synthesis of polyphosphonates by reaction of phosphonyl dichlorides with diols can be very rapid and, imder favorable conditions, give high molecular weights (99,100). 

It is clear from these results that the application of phase transfer catalyzed synthesis to polycondensation has high potential value. With the proper choice of conditions, activated dihalides react readily with divalent nucleophiles including bisphenols, dithiols, and active methylene compounds in organic solvent-aqueous alkaline solution system to yield various types of condensation polymers such as polysulfonates, polyphosphonates, polyethers,7 polysulfides,S 10,18,19 and carbon-carbon chain polymers.14,15... 

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