Cross with vinyl silane

Shah, G.B. Fuzail, M. Answar, J. Aspects of cross-linking of polyethylene with vinyl silane. J. Appl. Polym. Sci. 2004, 92, 3796-3803. 

Radical-mediated silyldesulfonylation of various vinyl and (a-fluoro)vinyl sulfones 21 with (TMSlsSiH (Reaction 25) provide access to vinyl and (a-fluoro)vinyl silanes 22. These reactions presumably occur via a radical addition of (TMSlsSi radical followed by /)-scission with the ejection of PhS02 radical. Hydrogen abstraction from (TMSlsSiH by PhS02 radical completes the cycle of these chain reactions. Such silyldesulfonylation provides a flexible alternative to the hydrosilylation of alkynes with (TMSlsSiH (see below). On oxidative treatment with hydrogen peroxide in basic aqueous solution, compound 22 undergoes Pd-catalyzed cross-couplings with aryl halides. 

Cross-linked beads made by vinylic polymerisations usually have some residual polymerisable functionalities [8], which allows the secondary imprinting polymerisation to covalently attach to the bead structure giving very stable particles. Where glass or silica is used a pretreatment with vinyl [9] or methacryloxy [2] silane derivatives ensures stable covalent attachment, while at the same time blocking surface silanol groups which might otherwise interfere with imprinting. 

The same reaction conditions were applied to the coupling reaction of Trimethyl(vinyl)silane [Eq.(3)] with limited success [3], Thus, the mechanism of these silicon-based reactions appears to be different from those of the cross-coupling reactions using the main-group metal reagents. 

The reaction of vinyl-substituted silanes and octavinylsilsesquioxane with vinyl-substituted amides, amines (carbazole) as welt as boronates catalyzed by I proceeds effectively to yield under optimum conditions stereo- and/or regio-selectively l-silyl-2-/V- and 1,1-silylboryl-substituted ethenes. 1-silylvinyl carbazole can also be obtained via cross-metathesis of vinylsilane with vinylcarbazole, but only in the presence of the 2nd generation Grubbs catalyst (IV). 

Palladium-catalyzed cross couplings of organofluorosilanes with vinyl [37] and aryl [38] halides and triflates are known, where the activation of the Si—C bond by fluoride ion plays an essential role in the coupling. The pentacoordinated fluoroorganic silanes promote the transmetallation to the aryl halide-palladium complexes strongly. At least one fluorine... 

We sought to examine the enzymatic dioxygenation of aryl silanes using a number of different aromatic dioxygenases in order to determine if such transformations were possible and to define the substrate-specificity profile. We were also motivated by the rich chemistry of silicon-based materials, which includes the hydrosilylation of alkenes and ketones, the addition of electrophiles to vinyl and allyl silanes, and palladium catalyzed cross-coupling of vinyl silanes with aryl halides (13). As a result, silyl functional cw-diols have potential as chiral intermediates for drug development, as polymer precursors/modifiers and as elements in non-linear optical materials. 

In the vinyl silane cross-linking process Sioplas process) developed by Dow, an easily hydrolysable trialkoxy vinyl silane, CH2=CHSi(OR)3, is grafted onto the polyethylene chain, the site activation having been achieved with the aid of a small amount of peroxide. The material is then extruded onto the wire. When exposed to hot water or low-pressure steam, the alkoxy groups hydrolyze and then condense to form a siloxane cross-link ... 

For further improvement of thermal properties of the polymer, some functional groups, such as vinyl, hydride, hydroxy, and epoxy groups, instead of a methyl group on the silylene unit were introduced into the polymer structure. Tris(penta-fluorophenyl)borane [B(CgF5)3] was also found very effective for the formation of siloxane bond by cross-condensation between silane and silanol or alkoxysUane. We used this catalyst to synthesize polysiloxanes with cage silsesquioxane in place of... 

Some alkenes with heteroatoms can be used in cross-coupling reactions. Vinyl boranes are an important group, as the carbon-boron bond can subsequently be converted into so many other functional groups, such as halides (Scheme 8.97). ° An example of cross-metathesis of a vinyl borane, followed by Suzuki coupling, can be found in Scheme 11.40. An example of a vinyl silane metathesis can be found in Scheme 2.110. 

Whereas the vinyl groups of Da are accessible for functionalization by hydroboration or hydrosilylation, they are inert to functionalization by cross-metathesis. Alternatively, formal metathesis products can be obtained by the ruthenium-catalyzed silylative coupling reaction. This method involves the combination of a vinyl silane and an olefin in the presence of a ruthenium catalyst, to provide an alkenylsilane (see eq 7). The application of this reaction to Da provides substitution at each of the four vinyl groups, resulting in a cyclic tetraalkenyltetramethylcyclote-trasiloxane. The silylative coupling reaction of both Da and has been demonstrated with styrenes and enol ethers. ... 

The basic chemistry of this process is that a silane such as tri-methoxy vinyl silane is grafted on to polyethylene and following extrusion the insulated wire or pipe is exposed to hot water or steam. The silane groups react with the water to form cross links with the elimination of methanol (Figure 12.13) [11]. A tin catalyst such as dibutyl tin dilaurate speeds up the crosslinking reaction. 

The synthesis of vinyl iodides and bromides starting from unactivated styrenes has been achieved using a silylative coupling reaction, followed by trapping with NXS (Scheme 7.125) [188]. The authors focused on the preparation of vinyl iodides and bromides due to their popularity in transition metal-catalyzed cross-coupling reactions. The first step in the synthesis was a ruthenium-catalyzed silylative coupling using the vinyl silane. The intermediate vinyl... 

Gross-Linking. A variety of PE resins, after their synthesis, can be modified by cross-linking with peroxides, hydrolysis of silane-grafted polymers, ionic bonding of chain carboxyl groups (ionomers), chlorination, graft copolymerization, hydrolysis of vinyl acetate copolymers, and other reactions. 

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