Polymeric dioxaphospholanes

Finally, the stereospecificity of the phosphorane-promoted cyclodehydration is adequately demonstrated in the reaction of d,Z-2,3-butanediol (9) with DTPP in CD2CI2 (35 C, 10 h). The stepwise nature of the cyclodehydration process gives exclusively d5-2,3-epoxybutane (10 >99%) by NMR analysis [6 12.9 (CH3) and 52.4 (CHO)] (76). This latter result is consonant with the previous findings of Denney etal. 24) where a mixture containing 88% d,/- and 12% zne5o-4,5-dimethyl-2,2,2-triethoxy-1,3,2X5-dioxaphospholanes (11) gave a mixture of 85% cis- and 15% /rans-2,3-butene oxides (10), respectively, during tiiermolysis (117°C, 42 h) (equations 2 and 3). Polymeric Dioxaphospholanes. 

The following groups of P-containing compounds were cationically polymerized 2-substituted-2-oxo-l,3,2-dioxophospholanes (ODPL) and the corresponding phos-phorinanes (ODPR), 2-substituted-l,3,2-dioxaphospholanes (DPL) and phosphori-nanes (DPR), 2-substituted-l,3,2-oxazaphospholidines (OAP) and 2-substituted-1,2-oxaphospholanes (OPL) ... 

Ring-opening polymerization of 4-methyl-2-oxo-l,3,2-dioxaphospholane yielded the following structures [292] ... 

Table 6.1 Ring-opening polymerization of 2-alk(aryl)o>y-2-oxo-l,3,2-dioxaphospholanes.

Nevertheless, most of the work reported on the post-polymerization modification of poly(all lene H-phosphonate)s concerns the functionalization with reactive pendant groups that include hydroxyl or amino groups, which make possible the introduction of a wide range of (bio)ac-tive molecules and leading to new reactive PPEs with tunable properties for biomedical applications. Most of the post-polymerization functionalization methods involve the corresponding polymeric chlorophosphite, since it was early demonstrated that cyclic allgrlene chlorophosphites such as 2-chloro-2-oxo-l,3,2-dioxaphospholane cannot be polymerized efficiently. ... 

Polyphosphoesters (PPE) is another important class of biomedical polymers [70] that can be prepared by stannous octoate catalyzed coordination-insertion polymerization method. A representative example is the synthesis of polyfethylene ethyl phosphate) (PEEP) as reported by Xiao et al. by the polymerization of the cyclic phosphoester 2-ethoxy-2-oxo-l,3,2-dioxaphospholane (EEP) using stannous octoate and dodecanol [71] (Fig. 2.20). 

Xiao, C.-S., et al. 2006. Kinetics and mechanism of 2-ethoxy-2-oxo-l,3,2-dioxaphospholane polymerization initiated by stannous octoate. Macromolecules 39(20) 6825-6831. 

Poly(phosphoester)s are polyphosphates obtained through ring-opening polymerization of cyclic phosphoester monomers poly(2-methoxy-2-oxo-l,3,2-dioxaphospholane), or poly(methyl ethylene phosphate), is not reported to show the LCST tjehaviour poly(phosphoester)s are biodegradabile and biocompatible [433-438]... 

In contrast, the polymerization of 2-oxo-l,3,2-dioxaphospholane (R = -(CH2>2 ) occurs much more rapidly, and no initiator is needed. This polymerization is approximately 85% complete at 24 C. Unlike the previous equilibrium, this is quite rapid, and the polymer cannot be purified by fractional precipitation. A variable temperature NMR... 

The polymerization of 4-methoxymethyl-2-oxo-l,3,2-dioxaphospholane (R = -CH2CH(CH20CH3)-) is different from either of the above polymerizations. The monomer does not self polymerize, and the polymerization goes to approximately 60 % completion at ambient temperature with tri-isobutylaluminum as an initiator. The polymer cannot be separated from the monomer by fractional precipitation. It was not possible to carry out variable temperature P NMR spectroscopic studies of this polymerization, because of the the variety of phosphorus environments in the polymer cause the P NMR resonance of the polymer to be very complex. 

Some of the freshly distilled monomeric cyclic P compounds polymerize spontaneously at room temperature in bulk or in solution for example, 2-methyl-1,3,2-dioxaphospholane (9) could not be isolated because of its fast oligomerization. ... 

Methoxy-2-oxo-l,3,2-dioxaphospholanes (10) ethoxy-2-oxo-l,3,2-dioxaphospholanes (11) were polymerized over a wide range of temperatures, namely, from -20 to 120 C... 

The same initiating system ((Bu )3Al) gave high polymers (Mw SxlO ) in the polymerization of optically active, as well as racemic 2-hydro-4-methyl-2-oxo-1,3,2-dioxaphospholane (24).The structure of the resulting polymer (H-H, H-T, and T-T) was analyzed in detail. ... 

Polymerization of cyclic phosphates was studied in detail only for 2-alkoxy-2-oxo-l,3,2-dioxaphospholanes and 1,3,2-dioxaphosphorinanes (19)29/44,48 different... 

Scheme 2 Influence of the polymerization conditions of 2-alkoxy-1,3,2-dioxaphospholanes (41) on the structure of the resulting polymers.

Hydroxyethoxy)ethoxy)-2-oxo-1,3/2-dioxaphospholane (51) was polymerized in bulk at temperature < 60 °C without a catalyst As a result, a water-soluble hyperbranched polyphosphate (poly-51), having many hydroxyl groups and degree of branching equal to 0.47, was formed. ... 

Table 1 Thermodynamic parameters of polymerization of 2-methoxy-2-oxo-1,3,2-dioxaphospholane (10) and 2-R-2-X-1,3,2-dioxaphosphorinanes (19, 22, 28)...

As an example of phosphorus-containing heterocyclic monomers, Yan et al. recently presented the first synthesis of a water-soluble hyperbranched polyphosphate by SCROP, using the new inimer 2-[(2-hydroxyethoxy)ethoxy] 1,3,2-dioxaphospholan-2-one (HEEP). Polymerization was... 

Figure 4 Plot of MJMn and Mp vs. monomer conversion for the polymerization of 2-isopropoxy-2-oxo-1,3,2-dioxaphospholane (IPP) by using DBU as the catalyst. Broken lines suggest the theoretical amount of each polymerization condition. Reproduced with permission from Iwasaki, Y. Yamaguchi, E. Macromolecules 43, 2664-2666. ...

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