H(OEt2)2[P(1,2-O2C6Cl4)3]: Synthesis, Characterization, and Application as a Single-Component Initiator for the Carbocationic Polymerization of Olefins

Authors

  • Paul W. Siu,

    1. Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1 (Canada), Fax: (+1) 604-822-2847
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  • Khatera Hazin,

    1. Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1 (Canada), Fax: (+1) 604-822-2847
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  • Prof. Dr. Derek P. Gates

    Corresponding author
    1. Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1 (Canada), Fax: (+1) 604-822-2847
    • Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1 (Canada), Fax: (+1) 604-822-2847
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Abstract

The development of novel Brønsted acids featuring the hexacoordinate phosphorus(V) anion [TRISPHAT] {[1]=[P(1,2-O2C6Cl4)3]} are reported. The title compound, H(OEt2)2[1], was synthesized from 1,2-(HO)2C6Cl4 (3 equiv) and PCl5 in the presence of diethyl ether. This compound was fully characterized by 1H, 31P and 13C NMR spectroscopy, X-ray crystallography and elemental microanalysis. Dissolution of H(OEt2)2[1] in acetonitrile results in the slow precipitation of crystalline H(OEt2)(NCMe)[1], which was characterized by X-ray diffraction; however, in CD2Cl2 solution the [TRISPHAT] anion protonated and ring-opened. The weighable, solid H(OEt2)2 [1] was found to be a competent initiator for the polymerization of n-butyl vinyl ether, α-methylstyrene, styrene and isoprene at a variety of temperatures and monomer-to-initiator ratios. At low temperatures, polymers with Mn>105 were obtained for n-butyl vinyl ether and α-methylstyrene whereas slightly lower molecular weights were obtained with styrene and isoprene (104<Mn<105). The poly(α-methylstyrene) synthesized at −78 °C is syndiotactic-rich (ca. 87 % rr) whereas the polystyrene obtained at −50 °C is atactic. The polyisoprene obtained possessed all possible modes of enchainment as well as branched and/or cyclic structures that are often observed in polyisoprene.

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