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Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid
Published on: November 15, 2017
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Directed C-H Halogenation Reactions Catalysed by PdII Supported on Polymers under Batch and Continuous Flow
Maitham H Majeed1, Payam Shayesteh2, Per Tunå3
1Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, 221 00, Lund, Sweden.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|August 17, 2019
Summary
New polymer-supported N-heterocyclic carbene palladium(II) catalysts enable efficient and recyclable C-H halogenation of arenes. These robust catalysts show high activity and selectivity in both batch and continuous flow systems, with no palladium leaching.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Polymer Science
Background:
- N-heterocyclic carbene (NHC) ligands are crucial in organometallic chemistry.
- Palladium(II) complexes are widely used as catalysts.
- Heterogeneous catalysts offer advantages in separation and recyclability.
Purpose of the Study:
- To develop novel polymer-supported NHC-Pd(II) complexes.
- To evaluate their efficacy as heterogeneous catalysts for directed C-H halogenation.
- To assess catalyst stability and recyclability in batch and flow conditions.
Main Methods:
- Synthesis and characterization of vinyl-functionalized NHC-Pd(II) monomers.
- Copolymerization with divinylbenzene to form polymer-supported catalysts.
- Application in directed C-H halogenation of arenes and performance evaluation.
Main Results:
- Developed robust polymer-supported NHC-Pd(II) catalysts.
- Achieved up to 90% conversion and 100% selectivity in chlorination.
- Demonstrated high recyclability (≥6 times) with minimal palladium leaching in batch mode.
- Exhibited exceptional activity and selectivity in continuous flow for ≥6 days without leaching or activity loss.
Conclusions:
- Polymer-supported NHC-Pd(II) complexes are effective heterogeneous catalysts for C-H halogenation.
- The catalysts are robust, recyclable, and suitable for both batch and continuous flow processes.
- These findings offer a sustainable approach to arene functionalization with minimal environmental impact.
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