Synthesis and characterization of Ti(Tbse)2 and its application as a catalyst for ROP of rac-Lactide

A novel bis(3,5‐di‐ tert‐butylsalicylaldehyde‐co‐ethanolamine) titanium(IV) complex (Ti(Tbse)2) was synthesized and structurally characterized. The X‐ray diffraction results showed that the titanium ion was bonded with two 3,5‐di‐tert‐butylsalicylaldehyde‐co‐ethanolamine ligands (Tbse ligands) in O,N,O‐tridentate mode. Experimental results revealed that the Ti(Tbse)2 complex could efficiently catalyze the ring‐opening polymerization (ROP) of rac‐lactide and showed a well‐controlled manner at 160 °C, and the polymers obtained had a controlled molecular weight and low polydispersity indices. Kinetic studies showed that the polymerization reaction was second order in monomer concentration and first order in catalyst concentration, and the apparent activation energy (Ea = 77.0 kJ mol−1) and frequency factor (A = 3.3 × 1011) were obtained according to the Arrhenius equation. 13C nuclear magnetic resonance spectra and thermogravimetric and differential scanning calorimetry analysis indicated that the polylactide was essentially a heterotactic and thermally stable polymer. Copyright © 2012 Society of Chemical Industry The crystal structure of Ti(Tbse)2 complex showed that the titanium ion was bonded with two 3,5‐di‐tert‐butylsalicylaldehyde‐co‐ethanolamine ligands (Tbse ligands) in O, N, O‐tridentate mode. The Ti(Tbse)2 complex could efficiently catalyze the ring‐opening polymerization (ROP) of rac‐lactide and showed a well‐controlled manner.