Platinum divinyltetramethyldisiloxane

Platinum deposition techniques, 79 157 Platinum dichloride, 79 655 Platinum-divinyltetramethyldisiloxane complex, in silicone network preparation, 22 563 Platinum films, 79 658 Platinum gauze catalyst, 77 180-181 Platinum-group metal compounds, 79 635-667 analysis of, 79 637 economic aspects of, 79 635-636 health and safety factors related to, 79 658... 

A mixture of 1,4-bis-dimethylsilylbenzene (7.9 mmol), the step 1 product (2 mmol), 10 ml toluene, and two drops of a solution of platinum-divinyltetramethyldisiloxane... 

A round-bottom flask consisting of a mixture of 1,4-bis-dimethylsilylbenzene (25.7 mmol), allyl methacrylate (51.4 mmol), 20 ml of toluene, and two drops of platinum divinyltetramethyldisiloxane complex dissolved in xylene were stirred at ambient temperature for 17 hours. The mixture was then loaded onto a silica gel column and eluted with a mixture of ethyl acetate/hexane, 20,80, respectively, and then concentrated and 7.8 g product isolated as a colorless oil having a viscosity of 136 cP. 

Vinyltrimethylsilane (97%), trimethylchlorosilane (98%), chlorodimethylsilane (97%), bromoform (96%), 5-bromo-l-pentene (95%), nBuLi (2.5M solution in hexanes), MeLi (1.6M solution in diethyl ether), n-decane (puriss. p.a., standard for GC, > 99.8%) and hexachloroplatinic(lV) acid hydrate were purchased from Aldrich. Platinum divinyltetramethyldisiloxane complex (Karstedt s catalyst, 3% solution in xylenes), hexamethyl-cyclotrisiloxane (95%), vinylmethyldichlorosilane (97%) and 1,1,3,3-tetramethyldisiloxane (97%) were bought from ABCR. Bromine (puriss) was bought from Eluka. Triethylamine (pure for analysis) and zinc oxide (pure) was purchased from Chempur. Solvents (tetrahydrofurane, diethyl ether, methylene chloride, pentane, ethyl acetate) were supplied by POCh (Polish Chemical Reagents). 

The tris(trimethylsilyl)methyl modified oligosiloxanes bearing also reactive alkoxy side substituents can be made in a simple one-pot/two step hydrosilylation reaction procedure in the presence of a platinum divinyltetramethyldisiloxane complex. 

Transition metal complex catalyzed ring-opening polymerization is fairly general and many other types of ferrocenylsilanes have also been polymerized by this methodology. For example, ferrocenophanes containing acetylide substituents as well as etheroxy substituents have been polymerized by the use of Karstedt s catalyst (platinum-divinyltetramethyldisiloxane complex) (Fig. 8.25) [56]. 

Hydrosilylation is generally catalyzed by Group 8-10 (VIII) metal complexes or supported metal catalysts. Platinum complexes are the most widely used, although rhodium(I) complexes have also been reported (83). Typical industrial catalysts include soluble platinum species such as the platinum-divinyltetramethyldisiloxane complex (Karstedt s catalyst) (221). These catalysts exhibit high turnover rates and are useful in concentrations as low as 1-2 ppm. 

In the Pt(0)-catalyzed hydrosilation, the addition of a catalytic amount of Na(0) appears to be necessary to achieve high levels of regioselectivity (cf., 1,1- vs 1,2-disubstituted vinylsilane). Without the inclusion of Na(0), the reaction yields a minor regioisomer, ( )-2-(dimethylphenylsilyl)-1 -buten-3-ol, 2b, in a ratio of 10-15 1. The checkers found that the reaction was considerably faster and higher-yielding with 60 mg of the catalyst, bis(T(-divinyltetramethyldisiloxane)tri-tert-butyIphosphine-platinum(O). 

Cuadrado et al. reported that hydrosilylation of 1,3,5,7-tetramethylcy-clotetrasiloxane (1) with four equivalents of vinylferrocene (2) in the presence of catalytic bis(divinyltetramethyldisiloxane)platinum(0) yielded tetraferrocenyl compound 3 in 92% yield (Scheme 1). The cyclic voltammogram of 3 exhibited a single reversible oxidation wave and coulometry established that this wave corresponded to the removal of four electrons per molecule, suggesting that the four ferrocenyl units act as independent, non-interacting redox centers. ... 

As shown in Scheme 45, DMSB can undergo polymerization or dimerization in the presence of similar platinum catalysts in good to excellent yields. The course of the reaction is apparently linked to the presence or absence of phosphine ligands platinum complexes that include added phosphines lead to dimerization, whereas polymerization usually occurred under ligandless conditions. Divinyltetramethyldisiloxane also serves as a ligand for the platinum-catalyzed dimerization of SCBs and disilacyclobutanes as reported by Chu and Frye <1993JOM(446)183>. 

Platinum catalyst preparation a mixture of 1 g of chloroplatinic acid hexahydrate, 12.4 mL (22 equiv) of 1,3-divinyltetramethyldisiloxane (an excess), and... 

T-Olefin platinum(O) complexes are important starting materials for oxidative addition see Oxidative Addition) or catalysts. Karstedt s catalysts, which are the most active ones for hydrosilylation, have been structurally characterized and found to show the structure of Pt2(M y M y )3 (9), wherein = divinyltetramethyldisiloxane." A styrene analogue Pt°(styrene)3 provides a convenient route to get an r-alkyne platinum complex by displacement (Scheme 27). DFT calculations indicate that aUcyne in the... 

Further investigations showed that other platinum catalysts can also be used with high yields, for instance, platinumdichloride and the Karstedt catalyst, a plati-num(0)-divinyltetramethyldisiloxane complex [86], Oleochemicals with internal double bonds were also found to be reactive in platinum-catalyzed hydrosilylations [87] methyl linolenate (with two internal double bonds) reacted with chlorohydrosi-lanes giving yields up to 83%. The hydrosilylation of methyl linolenate (with three internal double bonds) gave a mixture of regioisomeric 1 1- and 2 1-hydrosilylation adducts, however, only in total yields of 40%. 

Early concepts regarding the extremely efficient hydrosilylation catalysis by chloroplatinic acid involved the reduction of the complex to colloidal platinum, which was believed to be the real catalyst. However, the reports by Lewis and co-workers (e.g., (131,132)) have shown that the processes leading to colloid formation can account for the high activity of a hydrosilylation catalyst based on the complexes of Pt(0) with olefins and dienes such as divinyltetramethyldisiloxane (Karstedt s catalyst) and cyclooctadiene. The reactivity order of platinum group... 

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