Continuous Ligand-Free Catalysis Using a Hybrid Polymer Network Support

Area of Science:

• Chemical Engineering
• Materials Science
• Organic Chemistry

Background:

• Traditional batch homogeneous reactions face limitations in pharmaceutical and fine chemical industries.
• Continuous flow reactors offer potential improvements but require effective heterogeneous catalysis.
• Developing robust and versatile catalytic systems is crucial for intensified chemical synthesis.

Purpose of the Study:

• To design and evaluate a versatile network-supported palladium (Pd) catalyst for continuous flow synthesis.
• To optimize the catalyst and process parameters for Suzuki-Miyaura cross-coupling and nitroarene hydrogenation.
• To demonstrate the industrial applicability of the developed heterogeneous catalytic system.

Main Methods:

• Synthesis of a hybrid polymer network using poly(methylvinylether-alt-maleic anhydride) and branched polyethyleneimine.
• Immobilization of palladium (Pd) onto the hybrid polymer support.
• Utilizing automated exploration for parameter and substrate scope screening in continuous flow reactors.
• Performing Suzuki-Miyaura cross-coupling and nitroarene hydrogenation reactions.

Main Results:

• Achieved steady-state yields up to 92% for Suzuki-Miyaura cross-coupling with aryl bromides in 20 min residence time.
• Demonstrated high activity and mechanical stability with no detectable Pd leaching up to 95 °C.
• Obtained >99% yields for nitroarene hydrogenation in <2 min residence time at room temperature, with over 20 h of continuous operation without deactivation or leaching.

Conclusions:

• The hybrid network-supported Pd catalyst is effective for intensified continuous flow synthesis of complex organic compounds.
• The catalytic system offers high yields, stability, reusability, and environmental benefits, making it suitable for industrial applications.
• This versatile heterogeneous catalyst system addresses shortcomings of traditional batch processes and enables efficient chemical transformations.