Ruthenium Catalyzed Synthesis of Cross-Conjugated Polymers and Related Hyperbranched Materials. Copoly(arylene/1,1-vinylene)s

Abstract

Dihydridocarbonyltris(triphenylphosphine)ruthenium catalyzed copolymerization of acetophenone and 1,4-bis((trimethylsilyl)ethynyl)benzene yields a linear copolymercopoly[2-acetyl-1,3- phenylene/α,α‘-bis((trimethylsilyl)methylene)-1,4-xylenylene]. This reaction involves regioselective catalytic addition of the ortho C−H bonds of acetophenone across the C−C triple bonds of 1,4-bis((trimethylsilyl)ethynyl)benzene such that the hydrogen becomes bonded to the carbon which bears the trimethylsilyl group. A similar ruthenium catalyzed reaction between 1,4-bis((trimethylsilyl)ethynyl)benzene and 2-methylacetophenone has been used to prepare α,α‘-1,4-bis-[β-(trimethylsilyl)-2-acetyl-3-methylstyrenyl]benzene, a monomeric compound which possesses the same type of chromophore as the linear polymer. Analogous ruthenium catalyzed reaction of 4-((trimethylsilyl)ethynyl)acetophenone yields a hyperbranched material. All three of these cross-conjugated unsaturated materials have regularly alternating arylene and 1,1-vinylene units. These materials have been characterized by 1H, 13C, and 29Si NMR and by IR, UV, and fluorescence spectroscopy. Polymer properties have been measured by GPC, DSC, and TGA.