Phosphonic diisocyanates

Enol ethers from (2-oxoalkyl)phosphonic diesters are themselves highly reactive in hydrolysis and addition reactions. (2-Butoxyethenyl)phosphonic dichloride in CCI4 solution readily adds bromine in the cold, but attempts to distil the resultant (1,2-dibro-mo-2-butoxyethyl)phosphonic dichloride result in dehydrobromination the product 334 is unreactive to further attempted bromination, but suffers ready hydrolysis to (1-hydroxy-2-oxoethyl)phosphonic acid, and similarly, hydrolysis of the precursor dichloride yields (2-oxoethyl)phosphonic acid. Reactions between enol ethers and amides, carbamates or phosphoramidates, under acidic conditions, yield the enamides 335 [R = CO-alkyl, CO-aryl, COO-alkyl or P(0)(0Pr%f (2-Alkoxyethenyl)phosphonic diisocyanates act as precursors to phosphapyrimidines 336 and analogous phosphapurines ... 

A common approach with segmented PUs has been to incorporate a P-containing group (phosphate, phosphonate, phosphine oxide, or phosphazene) into a diol which is then chain-extended with a diisocyanate (e.g., Structures, 5.20 and 5.21).73,74 In one such study,75 phosphonate was found to be a more effective flame retardant than phosphate at the same phosphorus concentration, and in... 

P-Mannich bases arc prepared from phosphonic esters possessing hydroxy groups. -" Representative compounds of this type are 420 (Fig. 160), which give cross-linked polyurethanes of structure 421, by reaction with diisocyanates. 

Only dibutyl H-phosphonate has been reported to be used directly (together with other cocatalysts) for the preparation of isotactic polypropylene [125], Most of the other catalysts based on dialkyl H-phosphonates comprise of their metal and anunonium derivatives. Sodium dialkyl phosphite is used as a catalyst for the cyclotrimerization of 2,4-toluenedi-isocyanate with phenyl, m-chlorophenylene or a-naphthylisocyanates, forming oligomeric diisocyanates containing triisocyanurate cycles [126]. 

Phosphine copolymers can be obtained by heating primary phosphines with non-conjugated dienes (12.173), or condensing them with diisocyanates (12.174), or by reacting aryl phosphonous dihalides with certain aromatic hydrocarbons (12.175). 

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