A Highly Stable Porous Viologen Polymer for the Catalysis of Debromination Coupling of Benzyl Bromides with High Recyclability

Abstract

Abstract A highly stable porous organic polymer bipy‐POP has been prepared from the reaction of 4,4′‐bipyridine and tetrakis(4‐(bromomethyl)phenyl)methane in N ‐methylpyrrolidone at 110 °C. Bipy‐POP exhibited high efficiency in catalyzing the reductive debromination of a variety of benzyl bromides in N , N ‐dimethylformamide with dithionite as reductive reagent. For substrates that bear electron‐donating group(s) on the benzene ring, the reactions selectively afforded dibenzyl sulfone derivatives. Generally, substrates that bear an electron‐withdrawing group on the benzene ring gave rise to coupling products ethane derivatives. As exceptions, F, Cl or CF 3 ‐contained substrates were found to selectively produce sulfone derivatives. The recyclability of bipy‐POP for the catalysis of the reaction of (4‐fluorophenyl)methyl bromide and diphenylmethyl bromide, which afforded the corresponding sulfone or ethane derivative, revealed that, after 40 times of repeated use, the heterogeneous catalysis did not exhibit important decrease of the activity.