Silicon dichloride polymer

Sundar and Keller have reported the synthesis of linear boron-silicon-diacetylene polymers (31) (Fig. 21) using phenylboron dichloride (PBD) as the source for boron.50 The compositions of the thermally stable boron-silicon-diacetylene copolymers 31a-d are summarized in Figure 21. These polymers were observed to possess exceptional thermooxidative stabilities. 

Both Neish and Speakman Nature, 1945, 156, 176) and Wolsey and Alexander (Brit. Pat. 594901, 1947), showed that wool could be made unshrinkable by depositing upon it a silicon polymer. Alexander (J.S.D.C., 1950, 66, 349) considers that this is the only example of true masking of the scales with no spot welding involved. The process is described in detail by Alexander, Carter, and Earland J.S.D.C., 1949, 65, 107). The wool was treated with a substance of the general formula R.R. SiCl in an organic solvent such as carbon tetrachloride. The experiments were carried out with dimethyl silicon dichloride. The goods were immersed in the solution, hydroextracted, and then soaked in water at room temperature and dried, when the silicon compound was deposited on the surface of the fibres as an insoluble polymer. 

More recently, stable silylenes which are structurally the repeating unit of a polysilane chain have been prepared and characterized [14-15]. Their synthesis involves the reduction of silicon dichlorides. Two methods of synthesis are shown in the Fig. 7.7. Both of these procedures involve the preparation of cyclic compounds containing Si(II). Although these compounds are highly interesting from the point of view of their chemistry, they have not been shown to serve as precursors for polymers. 

A totally different kind of polymer is a poly-silylether. Dimethylsilyl dichloride polymerizes easily on treatment with hydroxide. Silicon is more susceptible to the Sn2 reaction than is carbon and long chains grow quickly. 

Commercially, silicones are thus not produced by polymer analog reaction, but are exclusively manufactured by the polycondensation or addition polymerization of low-molar-mass compounds. In addition to the poly(dialkyl siloxanes), the polycondensation of dialkyl silane dichloride with... 

In search for new oligomers and polymers containing hypervalent silicon chelates, the reactions of bis(trichlorosilyl)ethane (1) with O- and N-trimethylsilylated hydrazides (2 and 3, respectively) have been studied. The reaction of 1 with 3 was reported to lead to ionic binuclear disiliconium dichloride salts (4, Eq. 1) [1]. It was not obvious how the reaction of 2 with 1 might proceed would it form a neutral binuclear hexacoordinate complex, like the mononuclear analogues [2], or would it form ionic complexes, in analogy to 4 ... 

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