UBC Theses and Dissertations
From molecular to macromolecular and back : investigation of hexacoordinated phosphorus(v) anions and poly(methylenephosphine)s Siu, Paul Wai-Man
Alkali metal salts of tris(benzenediolato)phosphate –, K and Na, were prepared and examined as halide abstraction reagents. Compound K reacts with (dppp)PdCl₂ [dppp = 1,3-bis(diphenylphosphino)propane] (1:1 ratio) or [(cod)RhCl]₂ (2:1 ratio) to afford [(dppp)Pd(μ-Cl)]₂₂ and (cod)Rh, respectively. Brønsted acids H(DMSO)₂ and H(DMF)₂ were isolated as crystalline solids. The basicity of – was examined using IR spectroscopy and determined to be comparable to [BF4]–. Brønsted acid H(DMF)₂ is effective in the protonolysis of late transition metal-alkyl bonds. Its stoichiometric reaction with (dppe)PdMe₂ [dppe = 1,2-bis(diphenylphosphino)ethane] affords either [(dppe)Pd(NCMe)Me] (1:1 ratio) or [(dppe)Pd(NCMe)₂]₂ (1:2 ratio). Brønsted acid H(DMF)₂ initiates the cationic polymerization of n-butyl vinyl ether at 17 °C to afford moderate molecular weight poly(n-butyl vinyl ether) (Mn = 10,000 g mol-¹, PDI = 2.80). Brønsted acids of tris(tetrachlorobenzenediolato)phosphate –, H(OEt₂)₂ and H(OEt₂)(NCMe), were isolated as crystalline solids. Brønsted acid H(OEt₂)₂ was shown to be an effective initiator for the cationic polymerizations of n-butyl vinyl ether, styrene and isoprene. High molecular weight poly(n-butyl vinyl ether) was isolated from polymerization at –78 °C (Mn = 122,000 g mol-¹, PDI = 1.19). Atactic polystyrene of moderate molecular weight was isolated from polymerization at –50 °C (Mn = 55,400 g mol-¹, PDI = 1.62). Moderate molecular weight trans-polyisoprene was isolated from polymerization at –38 °C (Mn = 77,000 g mol-¹, PDI = 1.34). Poly(methylenephosphine) and poly(methylenephosphine) oxide were coated onto paper sheets made from thermomechanical pulp. TAPPI (Technical Association of Pulp and Paper Industry) Standard Method T461 cm-00 was used to evaluate the flame retardant properties of the polymers. Paper samples coated with the phosphorus-based polymers exhibited a higher degree of charring when compared to untreated paper and were comparable to paper treated with the monobasic ammonium phosphate standard. The microstructure of the 1-(2,2,6,6-tetramethylpiperidinyloxy)-1-phenylethane initiated poly(methylenephosphine) was examined by NMR spectroscopy. Evidence suggests the occurrence of 1,5-hydrogen abstraction rearrangement during the propagation step of polymerization. The unexpected microstructure was modeled using PhCH₂P(Mes)CHPh₂.
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