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Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
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Primary Anion-π Catalysis and Autocatalysis.
Xiang Zhang1, Xiaoyu Hao1, Le Liu1
1Department of Organic Chemistry , University of Geneva , Geneva CH 1211 , Switzerland.
Journal of the American Chemical Society
|December 14, 2018
Summary
Anion-π interactions enable epoxide-opening ether cyclizations on aromatic surfaces, showing autocatalytic amplification. This catalysis is enhanced by π-acidity, with significant rate increases observed on fullerenes and through product-mediated catalysis.
Area of Science:
- Organic Chemistry
- Supramolecular Chemistry
- Materials Science
Background:
- Epoxide-opening ether cyclizations are fundamental reactions in organic synthesis.
- Activating aromatic surfaces for catalysis often requires specific functional groups.
- The role of non-covalent interactions in catalysis is an area of active research.
Purpose of the Study:
- To investigate epoxide-opening ether cyclizations on π-acidic aromatic surfaces.
- To explore the potential for autocatalytic amplification in these reactions.
- To elucidate the mechanism of catalysis, particularly the role of anion-π interactions.
Main Methods:
- Experimental study of epoxide-opening ether cyclizations on various π-acidic surfaces (benzenes, NDIs, PDIs, fullerenes).
- Kinetic analysis to determine rate enhancements and catalytic efficiency.
- Computational studies (e.g., DFT) to model reaction mechanisms and transition states.
Main Results:
- Epoxide-opening ether cyclizations occur on π-acidic aromatic surfaces without additional activators.
- Catalytic activity increases with the intrinsic π acidity of the aromatic systems.
- Significant rate enhancements were observed, up to 270-fold for anion-π catalysis on fullerenes and 5100 M⁻¹ for autocatalysis.
- Autocatalysis was confirmed by increased initial rates in the presence of product.
Conclusions:
- Anion-π interactions are key to the observed catalytic activity.
- Autocatalysis plays a significant role, facilitated by hydrogen bonding between the transition state and product.
- The findings open new avenues for designing efficient catalytic systems based on non-covalent interactions on π-acidic surfaces.
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