Anthony C. Swain

Chloromethylation of poly(methylphenylsilane)

The chloromethylation of poly(methylsilane) is readily achieved using chloromethyl methyl ether in a tin(IV) chloride-catalysed reaction in chloroform solution at 0 °C. A convenient, less hazardous reaction, in which chloromethyl methyl ether is prepared in situ, is also reported. The accompanying variations of the polymer molecular-weight parameters are recorded for chloromethylations extending to 95% of the substituent phenyl groups, and discussed in terms of chain scissions arising at isolated siloxane linkages formed adventitiously during the isolation of the parent polymer.

Synthesis and characterization of tricarbonylmolybdenum-functionalized poly(methylphenylsilane)

The synthesis and characterization of a new metal-functionalized polysilane is reported. Treatment of poly(methylphenylsilane) with Mo(CO)(3)(NC5H5)(3) and BF3.OEt(2) affords the novel copolymer, poly(methylphenylsilane-stat-methyl (eta(6)-phenyltricarbonylmolybdenum)silane). The synthesis and characterization of the model compounds, (eta(6)-phenyltricarbonylmolybdenum)trimethylsilane, 1-phenyl-2-(eta(6)-phenyltricarbonylmolybdenum)tetramethyldisilane and 1,2-di(eta(6)-phenyltricarbonylmolybdenum)tetramethyldisilane, are used to support a full structural characterization of the copolymer. Copyright (C) 1996 Elsevier Science Ltd.

The formation of polysilanes from homogeneous reagents in tetrahydrofuran solution at low temperatures

Abstract Poly(methylphenylsilane) has been synthesized through homogeneous reductive dechlorination of dichloromethylphenylsilane using sodium/electron-acceptor complexes in tetrahydrofuran solution at −79°C. The optimization of product molecular weights is considered through analogy to a step-growth polymerization.

Chemical Modifications of Halomethylated Poly(Methylphenylsilane): A New and Facile Route to Functionalized Polysilanes

Soluble polysilanes are most commonly prepared using the Wurtz type reaction between dichloroorganosilanes and molten sodium metal in refluxing toluene1 or by the action of sodium dispersions in refluxing diethylether.2

Structure and mechanism in the cyclopolymerization of diallylsilanes

Abstract 13C- and 29Si-NMR spectroscopy are applied to the structural determination of the low molecular weight cyclopolymer formed from diallylmethylphenylsilane by a cationic mechanism. The ease of transfer to monomer, characteristic of the cyclopolymerization of diallylsilanes, is attributed to the ready formation of a resonance-stabilized chain-end structure.

THE SYNTHESIS, CHARACTERIZATION AND CATIONIC CYCLOPOLYMERIZATION OF DIALLYLSILANES

Abstract The preparation and spectroscopic properties of selected diaryl and alkylaryldiallylsilanes are reported together with a preliminary investigation of their aluminium tribromide initiated cyclopolymerization in toluene solution at various temperatures and monomer and initiator concentrations. Polymer yields and molecular weights are correlated with a simple mechanism for a Lewis acid initiated cationic polymerization. The polymerizations are compared with corresponding radical polymerizations and it is concluded that both types are dominated by degradative chain-transfer.

Poly(methylphenylsilane) with an enhanced isotactic content prepared using the graphite intercalation compound, C8K

Poly(methylphenylsilane) of Mw approaching 105, formed in association with the solid phase in the reaction of the potassium–graphite intercalation compound, C8K, with dichloromethylphenylsilane in THF at low temperatures has a significantly higher isotactic content than that formed using the conventional alkali metal reductive-coupling reaction.

A new insight into the polymodal molecular mass distributions arising in the Wurtz synthesis of polysilanes

In the light of recent understanding of the role and ultimate fate of alkali metals used in Wurtz syntheses of polysilanes, the polymodal nature of the molecular weight distributions that arise in the formation of poly(methylphenylsilane) are shown to be entirely consistent with an anionic mechanism of polymerization and explicable solely in terms of the heterogeneity of the reaction medium.

Low-temperature syntheses of polysilanes and polygermanes in diethyl ether

Both soluble and insoluble polysilanes and an insoluble polygermane have been prepared in high yield and at moderate temperatures from the interactions of alkylaryl-, diaryl-, and dialkyl-dichlorosilanes and diphenyldichlorogermane with sodium sand in the presence of 1,4,7,10,13-pentaoxacyclopentadecane (15-crown-5) in refluxing diethyl ether.

Alternative reducing agents for the Wurtz synthesis of polysilanes

Poly(methylphenylsilane) has been shown to be capable of formation from dichloromethylphenylsilane using metallic reducing agents other than the alkali metals that are invariably used in these Wurtz-type coupling reactions; for these preliminary studies yttrium and pyrophoric lead were chosen on the basis of electrochemical and mechanistic considerations, and their ready availability as powders of controlled particle size, and though these are far from ideal reagents for the purpose, they demonstrate the possibilities for tight control of these reactions being achieved through the use of alternatives to the alkali metals.