Aromatic biphenylene polymers: Synthesis via nickel coupling of aryl dichlorides

Abstract

A new method for the formation of high molecular weight aromatic biphenylene polymers via the nickel coupling of aromatic dichlorides is described. Aromatic biphenylene polymers display a number of highly attractive features which are discussed. The novel reaction is performed in a dry aprotic solvent (e.g., in DMAC) using catalytic amounts of zero‐valent nickel, triphenylphosphine ligand and excess zinc metal. The reactions must be performed under an inert atmosphere and in the absence of water. In order to obtain high polymer, one must use low amounts of nickel, high triphenylphosphine/nickel ratios, excess zinc metal, and moderate temperatures (70 °C). Variables such as the choice of ligand or co‐ligand, salt addition, ligand and zinc concentration, etc … allow for optimization of the reaction efficiency. The method is general and allows for the preparation of an almost infinite variety of polymers. Polymerizations and copolymerizations involving aryl dichlorides possessing dissimilar chloro‐moieties are particularly intriguing since a number of sequence distributions are possible. The two prerequisites for a successful preparation of high molecular weight product are solubility of the monomer, and more particularly of the obtained polymer, in the reaction medium; and the necessity that any functional groups present in the monomer(s) (and in the resulting polymer) be inert toward the zinc/nickel system. Critical features of the polymerization mechanism are also reviewed.

Aromatic Symmetric Cyclotrimers and Poly(arylenevinylene)s with Branched Aromatic Substituents in Vinylene Groups. Synthesis and Optical Properties

“…[14,15] Both of these factors determined our strategy for obtaining the polymers without structural defects.…”

Polymers Containing Sulfur, Polysulfones

“…Details of the method have been expounded (14)(15)(16)(17). References 14 and 15 are concerned with the synthesis of the diaryl halide intermediate whereas References 16 and 17 discuss the synthesis of the polymers, with emphasis on the polymerization of PPSF by this route.…”