Synthesis of polyphenylacetylene by iron(III) chloride catalyzed carbonyl olefin metathesis polymerization of chalcone

Carbon-carbon bond formation is a fundamental reaction in organic synthesis, one of its most important applications being synthesis of polymers and copolymers. Studies of the olefin metathesis reaction have resulted in extensive knowledge regarding synthesis of molecules applied in agricultural, petroleum, and pharmaceutical industries. The most commonly used catalysts for this purpose are ruthenium, molybdenum, and tungsten-based complexes. Recently, Ludwig et al. have successfully conducted iron(III)-catalysed carbonyl-olefin metathesis reaction for synthesis of low molecular weight compounds. In this study, we demonstrate for the first time that the carbonyl-olefin metathesis reaction, catalysed by anhydrous iron(III) chloride, can also be effectively applied in polymerization mode by using a single bifunctional monomer as chalcone. Polymerization was performed in a simple and efficient way under mild reaction conditions in solvents of various polarity, such as 1,2-dichloroethane and toluene. The average molecular mass of the synthesized oligomers reached 5000 g.mol −1 , which was higher than reference values so far reported. In situ doping of the as synthesized polyphenylacetylenes with FeCl3 represents another advantage of selected synthetic approach. Obtained products were characterized by gel permeation chromatography, 1 H NMR, and FTIR spectroscopy. The structure of the obtained oligomers was studied by X-ray diffraction analysis.