An Investigation of Alternate Synthesis for 2,2' -BIS(Phenylethynyl)-5, 5' -Diaminobenzidine

Abstract : Several routes were investigated to develop an improved lower cost synthesis of the cited tetramine; a critical monomer used in forming the polyphenylquinoxaline polymer system with 2,2'-bis(phenylethynyl) moieties for intramolecular cyclization to the fused dibenzoanthracene structure. An immediate precursor to the tetramine 4-bromo-5-phenylethynyl-0-phenylenediamine was prepared in 43% overall crude yield from 0-nitroamide. Activated coupling through the aryl bromide using the tris-(triphenylphosphine) Ni(0) species was unsuccessful. Substrate chelation of the Ni(0) via the 0-diamine functionality was suggested as an inhibiting mechanism.