Densmore, C.G. and P.G. Rasmussen, “New Acetylenic Monomers and Polymers from 4 Macromolecules and 5-Dicyano-imidazole”, Macromolecules, Vol. 37, pp. 5900-5910, 2004.
An efficient synthesis of 1-methyl-2-ethynyl-4,5-dicyanoimidazole via Sonogashira coupling is described. Our optimized method generates 1-methyl-2-ethynyl-4,5-dicyanoimidazole in almost 80% yield from 1-methyl-2-bromo-4,5-dicyanoimidazole. Syntheses of the ethyl, propyl, and p-methoxybenzyl derivatives of 2-ethynyl-4,5-dicyanoimidazole are also reported. The polymerization of 1-methyl-2-ethynyl-4,5-dicyanoimidazole with transition-metal catalysts and triethylamine is described. Variation of catalyst concentration, reaction time, and temperature is also described. A more complete mechanistic picture of acetylene polymerizations, especially those with electron-withdrawing substituents, is presented. Solid samples of 1-methyl-2-ethynyl-4,5-dicyanoimidazole oligomers are EPR-active, and the number of free spins was quantified. Cyclic voltammetry was used to investigate the reduction of 1-methyl-2-ethynyl-4,5-dicyanoimidazole oligomers and other dicyanoimidazole derivatives.