Chirality-Induced catalyst aggregation: insights into catalyst speciation and activity using chiral aluminum catalysts in cyclic ester ring-opening polymerization
File(s)
Author(s)
Gesslbauer, Sami
Hutchinson, George
White, Andrew
Burés, Jordi
Romain, Charles
Type
Journal Article
Abstract
A series of chiral-at-metal aluminum complexes have been synthesized using chiral catam ligands. Reactivity studies demonstrate the importance of alkoxide bulkiness and complex chirality in inducing catalyst aggregation. This has been exploited in cyclic ester ring-opening polymerization (ROP). For ε-Cl ROP, enantiopure catalysts were found to outperform a racemic mixture of catalysts, as the racemic mixture resulted in lower activity heterodimeric catalytic species and reduced polymerization rates. In the case of L-LA, one catalyst enantiomer was found to be the most active of the series and outperformed both the other enantiomer and the corresponding achiral catalyst. Very high activities were observed and up to 9,200 equivalents of L-LA were polymerized in 4.5 min at 150 °C with TOF > 100,000 h–1 under industrially relevant conditions. Analysis of the catalyst orders for these reactions provided a meaningful catalyst speciation-activity relationship enabling improved understanding of both catalyst speciation and the activity of each catalytic species involved in cyclic ester ROP using chiral aluminum catalysts.
Date Issued
2021-04-02
Date Acceptance
2021-02-24
Citation
ACS Catalysis, 2021, 11 (7), pp.4084-4093
ISSN
2155-5435
Publisher
American Chemical Society
Start Page
4084
End Page
4093
Journal / Book Title
ACS Catalysis
Volume
11
Issue
7
Copyright Statement
© 2021 American Chemical Society.
Subjects
Science & Technology
Physical Sciences
Chemistry, Physical
Chemistry
chiral aluminum catalyst
catalyst aggregation
ring-opening polymerization
lactide
epsilon-caprolactone
kinetic analysis
0302 Inorganic Chemistry
0305 Organic Chemistry
0904 Chemical Engineering
Publication Status
Published
Date Publish Online
2021-03-17