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- Title
Ring Opening Polymerization of Lactides and Lactones by Multimetallic Titanium Complexes Derived from the Acids Ph 2 C(X)CO 2 H (X = OH, NH 2).
- Authors
Zhang, Xin; Prior, Timothy J.; Chen, Kai; Santoro, Orlando; Redshaw, Carl
- Abstract
The reactions of the titanium alkoxide [Ti(OR)4] (R = Me, nPr, iPr, tBu) with the acids 2,2′-Ph2C(X)(CO2H), where X = OH and NH2, i.e., benzilic acid (2,2′-diphenylglycolic acid, L1H2), and 2,2′-diphenylglycine (L2H3), have been investigated. The variation of the reaction stoichiometry allows for the isolation of mono-, bi-, tri or tetra-metallic products, the structures of which have been determined by X-ray crystallography. The ability of the resulting complexes to act as catalysts for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and r-lactide (r-LA) has been investigated. In the case of ε-CL, all catalysts except that derived from [Ti(OnPr)4] and L2H3, i.e., 7, exhibited an induction period of between 60 and 285 min, with 7 exhibiting the best performance (>99% conversion within 6 min). The PCL products are moderate- to high-molecular weight polymers. For r-LA, systems 1, 3, 4 and 7 afforded conversions of ca. 90% or more, with 4 exhibiting the fastest kinetics. The molecular weights for the PLA are somewhat higher than those of the PCL, with both cyclic and linear PLA products (end groups of OR/OH) identified. Comparative studies versus the [Ti(OR)4] starting materials were conducted, and although high conversions were achieved, the control was poor.
- Subjects
LACTIDES; CARBON dioxide; TITANIUM; LACTONES; X-ray crystallography; RING-opening polymerization
- Publication
Catalysts (2073-4344), 2022, Vol 12, Issue 9, pN.PAG
- ISSN
2073-4344
- Publication type
Article
- DOI
10.3390/catal12090935