New aryloxy and benzyloxy derivatives of titanium as catalysts for bulk ring-opening polymerization of ε-caprolactone and δ-valerolactone

A variety of aryloxy compounds and benzyloxy derivatives of TiIV were synthesized from. Ti(iP:rO)4 using the alcoholysis route, These compounds were characterized using various analytical methods and single-crystal X-ray diffraction, MuItinuclear NMR studies prove high degree of fluxional behavior of these compounds in solution. They adopt a dimeric structure in the solid state as seen from. X-ray diffraction studies on a few of them., These compounds are powerful catalysts for the ring-opening polymerization of e-caprolactone (CL) and δ-valerolactone (VL) resulting in high polymers with good number average molecular weights (Mn), Signifi-cant control can be achieved by performing such polymerizations in the presence of benzyl alcohol (BnOH). This is reflected by higher Mn and much narrower molecular weight: distributions (MWDs) of the resulting polymers. Kinetic studies reveal that the rates of such polymerizations are much higher in the presence of BnOH, 1H NMR and MALDI-TOF studies of low molecular weight oligomers suggest: that these polymerizations proceed by the activated monomer mechanism in the presence of BnOH, © 2009 Wiley-VCH Verlag GmbH & Co, KGaA.