Phenylsilane, polymerization

Unlike pentamethylphenyldisilane, the photolysis of compound 5 in the presence of methanol in hexane gave no products arising from the reaction of a silene with methanol, but polymeric substances were obtained as main products, in addition to small amounts of bis-(trimethylsiloxy)phenylsilane (6) (4%) and bis(trimethylsiloxy)-phenylmethoxysilane (7) (5%). 

The functionalization of polymers is another useful feature of the hydrosilation reaction. The introduction of highly fluorinated alkyl chains by the hydrosilation of Si-H groups of the polymer with fluorinated aUcenes is a typical example. Poly(phenylsilanes) obtained by the dehydrocouphng polymerization of phenylsilane undergo AIBN initiated free radical hydrosilation with aUcenes, ketones and aldehydes. Cross-linking and branching of polymers can also be easily accomplished using hydrosilation. 

The mixture of CpTiCl3, ZnPh2, and MAO has been used to initiate the polymerization of styrene and its copolymerization with 1-hexadecene and with />-/rz -butylstyrene.471 (Ind)TiCl3 combined with ZnPh2 as additive and MAO has been used for the co-polymerization of styrene with 1-alkenes (1-hexene, 1-decene, 1-hexadecene).472 Similarly, CpTiCl3 has been used for the co-polymerization of styrene and p-tert-butylstyrene.473 The syndiotactic polymerization of styrene with Cp TiCl3 and octahydrofluorenyl trimethoxo titanium complexes in the presence of phenylsilane has been investigated.474... 

Fig. 1), is prepared by a dehydrogenalive coupling polymerization reaction between phenylsilane and r -dietbynyl benzene in the presence of magnesium oxide, which has an extremely high thermal stability by curation. 2 ... 

The polymer 17, prepared by the ADMET polymerization of neat diallyldi-phenylsilane using Mo(=CHCMe2Ph)(=NAr)[OCMe(CF3)2]2 (Anhaus 1991), can be degraded by diluting the living polymer solution with sufficient toluene. This gives a 30% yield of the tt cyclic dimer 18, which separates as a white precipitate. When this is isolated and placed in contact with further initiator, an equilibrium is established between the cyclic monomer 19 and the three cyclic dimers (cc ct ft = 73 21 6), eqn. (3) (Anhaus 1993). The formation of the tt cyclic dimer in the initial degradation of 17 is thus kinetically favoured. 

Poly(dimethylsilane) can be synthesized by electrochemical reduction of dimethyldichlorosilane in 30% yield [87] and poly(methylphenylsilane) has also been synthesized by reduction of PhMeSiCl2 [88]. In this method the problem is the oxidation of the anode by elemental chlorine to form metal chlorides, or the formation of corrosive hydrogen chloride [89]. Therefore the electrochemical polymerization of hydrosilanes like phenylmethylsilane, phenylsilane, or hexylsilane has also been investigated. Relatively low molecular weight polymers could be obtained in 32-70% yield [90] ... 

Also phenylene units have been introduced into polycarbosilane chains either by polymerization of a para-bromo phenylsilane [103] ... 

Of course, a mechanism involving initial reaction of metal hydride with phenylsilane will be most important early in the polymerization, when the monomer concentration is highest. Later in the reaction, the slower coupling of polysilanes may become more important. A process of the latter type is a cyclization, which would proceed via the transition state shown here ... 

The study was extended by polymerizing olefins with monomer containing a dimethylphenylsilane group. The phenylsilane moiety was separated from the double bond by six methylene groups [7-octenyl-Si(CH3)2Ph] and that was... 

Following the development of group 2 complexes for the controlled polymerization of styrene, in 2006 Harder and coworkers reported the hydrosilylation of a series of activated alkenes with Ph SiH4 (n = 2 or 3) catalyzed by [ (Me2N-o-C6H4) CHSiMes 2M(THF)2] (M = Ca, Sr) and isolated the first calcium-hydride complex [ (ArNCMe)2CH Ca p-H)(THF)]2, a species relevant to the catalytic reaction [116, 117], In related studies, Okuda and coworkers have isolated a cationic trinuclear calcium hydride cluster and demonstrated its competency for the hydrosilylation of styrene with phenylsilane (Fig. 10) [118]. 

Marks reported that phenylsilane CeHsSiHs acts as a chain transfer agent for homogeneous olefin polymerization catalysts [16]. Newman found that CeHsSiHs increased the catalytic activity in the styrene polymerization [17]. The polymerization conversions with time are shown in Table 4.3. The data... 

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