Premium
Directed C−H Halogenation Reactions Catalysed by Pd II Supported on Polymers under Batch and Continuous Flow Conditions
Author(s) -
Majeed Maitham H.,
Shayesteh Payam,
Tunå Per,
Persson Axel R.,
Gritcenko Roman,
Wallenberg L. Reine,
Ye Lei,
Hulteberg Christian,
Schnadt Joachim,
Wendt Ola F.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201902949
Subject(s) - palladium , selectivity , halogenation , catalysis , chemistry , pyridine , monomer , leaching (pedology) , polymer chemistry , carbene , organic chemistry , polymer , flow chemistry , combinatorial chemistry , environmental science , soil science , soil water
A new generation of N ‐ heterocyclic carbene palladium(II) complexes containing vinyl groups in different positions in the backbone of the N ‐ heterocycle have been developed. The fully characterised monomers were copolymerised with divinylbenzene to fabricate robust polymer supported NHC‐Pd II complexes and these polymers were applied as heterogeneous catalysts in directed C−H halogenation of arenes with a pyridine‐type directing group. The catalysts demonstrated medium‐high catalytic activity with up to 90 % conversion and 100 % selectivity in chlorination. They are heterogeneous and recyclable (at least six times) with no significant leaching of palladium in batch mode catalysis. The best catalyst was also applied under continuous flow conditions where it disclosed an exceptional activity (90 % conversion) and 100 % selectivity for the mono‐halogenated product for at least six days, with no leaching of palladium, no loss of activity and an ability to maintain the original oxidation state of Pd II .