C-13 NMR-STUDY OF POLY(PROPYLENE OXIDE)S PREPARED WITH ORGANOTIN-ALKYL PHOSPHATE CONDENSATES OF VARIOUS DEGREES OF CONDENSATION

Polymerizations of (S)- and (RS)-propylene oxides were carried out wit h various organotin-alkyl phosphate condensates derived from dibutylti n oxide (Bu2SnO) and tributyl phosphate (Bu3PO4) as initiators. Regioi rregularity of poly((S)-(-)-propylene oxide) was studied by C-13 NMR s pectroscopy based on revised peak assignments. The results suggest the presence of alternating irregular units as well as isolated ones, in contrast with poly((S)-(-)-propylene oxide)s formed with ZnEt2-H2O and AlEt3-H2O-(acetylacetone), in which only isolated irregular units exi st. The benzene-hexane insoluble fraction of poly((RS)-propylene oxide ) initiated with BU2SnO-Bu3PO4 (1 : 2) condensate, which was insoluble in a variety of organic solvents, had isotactic diad of 94% and isota ctic triad of 91%. The reactivity of Bu2SnO-Bu3PO4 (1 : 2) condensate was higher than that of BU2SnO-Bu3PO4 (1 : 4) condensate or Bu2SnO Bu3 PO4 (1 : 1) Condensate. Among the Bu2SnO-Bu3PO4 (1 : 2) condensates, h igh molecular weight condensate showed higher reactivity than the low molecular weight one.