SYNTHESIS OF CYCLOPHOSPHAZENES AND POLYPHOSPHAZENES WITH PYRIDINE SIDE-GROUPS

New types of cyclo- and polyphosphazenes that bear pyridine side group s have been synthesized. The reactions of 2-(2-aminoethyl)pyridine and 2-(2-aminoethyl)amino)-5-nitropyridine with (NPCl2)3 were complex, wi th chlorine replacement being complicated by degradation and the forma tion of mixtures. However, the use of electron-withdrawing cosubstitue nts, such as phenoxy or trifluoroethoxy groups, allows straightforward chlorine replacement reactions induced by the aminoalkylpyridines to occur. The mono(alkylpyridine)-substituted cyclotriphosphazenes N3P3(O C6H5)(5)(NHCH2CH2(C5H4N)) (1) and N3P3(OC6H5)(5)(NHCH2CH2NH(C5H3N)NO2) (2) were synthesized as model compounds for high polymers. Polyphosph azenes of the general formula [NP(OCH2CF3)(x)(NHCH2CH2(C5H4N))(y)](n) were prepared by exposing [NPCl2](n) to sodium trifluorethoxide and 2- (2-aminoethylpyridine in a two-step reaction. All compounds were chara cterized by H-1, C-13, P-31 NMR spectroscopy, and elemental analysis. The cyclic trimers were also identified by mass spectrometry. Molecula r weight estimations of the polymers were carried out by gel permation chromatography, and glass transition temperatures were determined by differential scanning calorimetry.