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(RO)(2)Ta[tris(2-oxy-3,5-dimethylbenzyl)amine]: structure and lactide polymerization activities
Youngjo Kim1, Pramesh N Kapoor, John G Verkade
1Department of Chemistry, Iowa State University, Ames, IA 50011, USA.
Inorganic Chemistry
|September 11, 2002
Summary
Novel tantalum complexes showed no activity in lactide polymerization, unlike related titanium compounds. This finding offers insights into catalyst design for producing polylactic acid (PLA).
Area of Science:
- Organometallic Chemistry
- Polymer Science
- Catalysis
Background:
- Atrane-like complexes are of interest in catalysis.
- Group 5 metal complexes are less explored as polymerization initiators compared to Group 4 metals.
Purpose of the Study:
- To synthesize and characterize novel atrane-like six-coordinate tantalum complexes.
- To evaluate the catalytic activity of these tantalum complexes in lactide polymerization.
- To compare their performance with related titanium analogues and simple metal alkoxides.
Main Methods:
- Synthesis of novel (RO)(2)TaL complexes.
- X-ray crystallography for structural characterization (specifically for the R=Me complex).
- Lactide polymerization experiments using l-LA and rac-LA.
Main Results:
- Successful synthesis and structural characterization of novel atrane-like tantalum complexes.
- The synthesized tantalum complexes were ineffective as single-site initiators for both isotactic and atactic polylactic acid (PLA) production.
- In contrast, tantalum ethoxide and several titanium analogues effectively catalyzed lactide polymerization.
Conclusions:
- Atrane-like tantalum complexes, despite their unique structure, do not initiate lactide polymerization.
- The electronic or steric properties of these specific tantalum complexes may hinder their catalytic activity.
- Titanium-based catalysts and simple metal alkoxides demonstrate superior performance for lactide polymerization.