Catalysts Speiers’ catalyst

Dimethyl- and 3,3-diethyl-l,3-thiasilacyclobutanes are obtained by intramolecular cyclization of the bis(chloromethyl)silane with hydrosulfide ion, as exemplified by the synthesis of 522 or by an intramolecular hydro-silation, as exemplified by the synthesis of 523. A chloroplatinic acid catalyst (Speiers catalyst) also has been used for the hydrosilation... 

Under the same reaction conditions traditional catalysts, such as H2PtCl6 in PrOH (Speier catalyst) and Pt2(divinyltetramethyldisiloxane)3 (Karstedt Catalyst) are completely inactive. 

The CVD method can form a polymethylsiloxane layer of 0.6-0.8 nm on the inorganic particles (Table 12.1.2). Especially, the polysiloxane-modified titanium oxide has been used for the additives to cosmetics. Moreover, residual Si-H group grafted on the particles reacted with unsaturated organic compounds in the presence of Speier catalyst (47), H2PtCl6, to be functionalized by organic pendant group [Reaction (11 ). ... 

Hydrosilylation. In addition to the two most prominent catalysts, Speier s catalyst (H2PtCl6 in 2-propanol) and the catalyst developed by Karstedt ([Pt(CH2=CHSi Me2)3], and Group VE metals, new families of catalysts have been developed and... 

It is well known that hydrosilylation of ethylene by trichloro- and methyldichlorosilanes easily proceeds in the presence of Speier catalyst (SC), wherein platinum is in the divalent state, at room temperature with practically quantitative adduct yield. Under similar conditions, triethoxysilane does not bond to ethylene. 

The studies of the interaction with these compounds were carried out using the hydridesilicas obtained through the chemisorption of methyidichlorosilane. The sSiH groups content was 2.4 pmol/m. The interaction between hydridesilicas and functional olefins was studied at the boiling temperature (82.4°C) of the solvent in the presence of the Speier catalyst. In order to do it a hydridesilica sample was placed into the glass reactor... 

Figure 4. IR spectra for hydridesilica with = Si-0-Si-H groups (1), treated with vinyl-trichlorosilane (2) or vinyltrimethylsilane (3) in the presence of the Speier catalyst and evacuated at 300°C for 1 hr. Curves (4) and (5) are IR spectra for vinyltrichlorosilane and vinyltrimethylsilane respectively.

Figure 7. IR spectra of hydridesilica (1), after the interaction with acrylamide in the presence of the Speier catalyst and evacuation at 300 C for 1 hr (2). (3)-IR spectrum of acrylamide.

The hydrosilylation reaction was effected using a liquid-phase process without any solvent, without access for light at 100°C for 3 hr in the presence of the Speier catalyst. Then the modified silica was washed with carbon tetrachloride for Ihr in a Sohxlet apparatus and evacuated at 300°C for 2 hr. As a result of this reaction the IR spectrum of the modified silica (Fig.8, spectrum 2) displayed a considerable decrease in the intensity... 

Figure 9. IR spectra of silica evacuated at 400°C for 2 hr (1), after the treatment with methyl alcohol at 380 C for 3 hr and evacuation at 300°C for 1 hr (2), after thermoevacuation at 700°C for 40 min (3), treated with hexamethyldisilazane at 100°C for 1 hr and evacuated at 400°C for 1 hr (4), after the treatment with 1-octene in the presence of the Speier catalyst and evacuation at 300°C for 1 hr (5).

In order to elucidate the nature of the possible influence of the phase state (in a solution or on surface) of H2C=CH- groups on the hydrosilylation reaction we carried out the studies [123,129] of the interaction between silica with attached =SiCH=CH2 groups and methyldichlorosilane using the Speier catalyst. 

Figure 12. Transmission electronic spectra for the system hydridesilica + Speier catalyst (silica plate 30 mg, 1=2 mm 0.001 N solution of H2PtCl6 in isopropyl alcohol) in 5 (1), 15 (2), 25 (3) and 35 min (4) after the addition of the catalyst 35 min after the addition of 1-decena to the system hydridesilica -h Speier catalyst (5). Spectrum (6) corresponds system starting silica -f Speier catalyst on 35 min.

Figure 13. Electronic spectra of the Speier catalyst (1) and of the system Speier catalyst + 1-decene (2) and Speier catalyst + hydridesilica (3) (-f- -- - experimental spectrum — differential components - - - integral envelope).

The contact of the Speier catalyst with hydridesilica and / or 1-decene leads to the... 

With allowance for the obtained spectral results the scheme of the solid-phase hydrosilylation process may be visualized as follows. Upon the contact with the Speier catalyst the hydridesilica forms complex I on its surface, then complex becomes coordinated with a molecule of 1-olefin, which gives structure II ... 

Transmission differentiated electronic spectra for systems containing hydridesilica, Speier catalyst, and 1-decene... 

Attempts to study the system =SiOSiCH=CH2 + Speier catalyst + hydride silica by electron spectroscopy failed for the impossibility to carry out experiments on hydridesi-lane in cells of optically transparent quartz. However, the IR spectroscopy data about the possibility of coordinating the Speier catalyst on the silica surface with vinyl groups and the results obtained when studying the mechanism of solid-phase catalytic hydrosilylation on silica surface allow us to suggest the following schemes of the catalytic hydrosilylation with the participation of vinyl-containing silica ... 

The hydrosilylation of 1-alkenes can be carried out with catalysts of subgroup VIII. Platinum compounds (especially, e.g., the Speier catalyst (H2PtCl6 H20) and the... 

Karstedt solution, a complex compound of H2PtCl6 (H20)6) and vinyl-substituted disiloxanes are well known and very active catalysts [19]. Several other catalytic systems, e.g., Pt(cod)2, leading to the formation of platinum colloids have been examined [20]. More recently, hydrosilylation with the Speier catalyst has been tested both under single- and two-phase conditions. The hydrosilylation reaction was thereby optimized for technical realization [21]. 

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