Shape-selective activation of C-H bonds in synthesis of biaryls
Two researchers of the Department of Inorganic Chemistry and Technology (D-09) participated in an interesting study of the shape-selective activation of inert C-H bonds to oxidatively couple two toluene molecules.
Oxidative coupling of simple aromatics allows for a cost-effective synthesis of biaryls. However, utilization of this technology is severely hampered by poor regioselectivity and by the limited stability of state-of-the-art homogeneous Pd catalysts. The authors showed that confinement of cationic Pd in the pores of a zeolite enables a selective activation of C-H bonds, where selectivity is determined by the shape of the zeolite pores. The concept was demonstrated with the synthesis of 4,4'-dimethylbiphenyl using the Pd-zeolite Beta as guest-host heterogeneous catalytic system. Out of six possible isomers, 4,4'-dimethylbiphenyl is produced with high selectivity (80%).
Andraž Krajnc and Gregor Mali from D-09 relied on NMR measurements to determine the proximities of neighbouring Pd(OAc) fragments and their bonding to the zeolite framework. The work was described in an article published in Nature Catalysis (IF=30,5).
Full text is available at https://www.nature.com/articles/s41929-020-00533-6
Contact for more information: gregor.mali(at)ki.si