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Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
N-halosuccinimide/BF3-H2O, efficient electrophilic halogenating systems for aromatics
G K Surya Prakash1, Thomas Mathew, Dushyanthi Hoole
1Donald P. and Katherine B. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, Los Angeles, California 90089-1661, USA. gprakash@usc.edu
Journal of the American Chemical Society
|December 2, 2004
Summary
N-Halosuccinimides (NXS) are efficiently activated by BF(3)-H(2)O, a cost-effective reagent, enabling the halogenation of deactivated aromatic compounds. This new method offers a practical approach for electrophilic aromatic substitution reactions.
Area of Science:
- Organic Chemistry
- Electrophilic Aromatic Substitution
Background:
- N-Halosuccinimides (NXS) are versatile halogenating agents.
- Activating NXS typically requires strong acids like trifluoromethanesulfonic acid.
- Halogenation of deactivated aromatic compounds remains a synthetic challenge.
Purpose of the Study:
- To develop a more economical and efficient method for activating N-Halosuccinimides.
- To enable the halogenation of deactivated aromatic substrates using NXS.
- To investigate the mechanism of NXS activation and halogenation.
Main Methods:
- Utilizing BF(3)-H(2)O as an activating agent for N-Halosuccinimides.
- Performing electrophilic halogenation reactions on deactivated aromatic compounds.
- Employing Density Functional Theory (DFT) calculations to study reaction mechanisms and intermediates.
Main Results:
- BF(3)-H(2)O efficiently activates NXS, comparable to trifluoromethanesulfonic acid but more economically.
- The NXS/BF(3)-H(2)O system successfully halogenates deactivated aromatic substrates.
- DFT calculations reveal the formation of superelectrophilic species responsible for halogen transfer.
Conclusions:
- The NXS/BF(3)-H(2)O system represents an efficient and cost-effective reagent combination for electrophilic halogenation.
- This method provides a valuable tool for synthesizing halogenated deactivated aromatics.
- Understanding the mechanistic pathways enhances the design of future halogenation strategies.
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