Hydrosilylation ethylene

Ethylene hydrosilylation with triethoxysilane has not yet been described in the literature. There are data concerning ethylene and propylene hydrosilylation in the presence of ihodium catalyst [RhCl(CO)2]2- However, it is known that a side reaction, dehydrogenating silylation, is typical for rhodium catalysts (Scheme 1). 

On the basis of the obtained results we can conclude that ethylene hydrosilylation reaction by triethoxysilane proceeds on Pt(0) compounds. 

Ethylene hydrosilylation with trimethoxysilane readily proceeds on KC and GC catalysts, synthesis being complete in l.S - 2 h, the ethyltrimethoxysilane content in the mixture being 66 - 76%. Vinyltrimethoxysilane was not identified in either experiment. 

Cyclopentadienyl complexes of Rh —> Rh appeared as valuable examples in the mechanistic study of ethylene hydrosilylation [14, 47]. GC/MS and NMR studies as well as deuterium labeling of the substrates allowed an alternative proposal to the Chalk-Harrod mechanism, initiated by a hydrogen shift to form... 

Ir(I), Ir(II) andlr(V) complexes stabilized by an O-donor ligand (e.g. [Ir(coe)(triso)] and [Ir(C2H4)2(triso)] (triso = tridentatetris(diphenyloxosphosphoranyl)methanides) are effective catalysts for the dehydrogenative silylation and hydrosilylation of ethylene [16-18]. 

The hydrosilylation of ethylene by the early-late transition-metal heterodinuclear complexes [CpTa( t-CH2)2lr(CO)2] has been studied mainly in a bid to recognize the mechanism of reaction, which occurs via a predominant alkene/Ir—H insertion pathway over a minor insertion of ethylene into the Ir—Si bonds [21]. 

Scheme 14.2 Competitive hydrosilylation and dehydrogenative silylation of ethylene and 1-hexene.

Scheme 14.4 Synthesis of poly(phenylene-silylene-ethylene)s via hydrosilylation polymerization process.

Double silylation of the a-diketone 120 with (Me3Si)2 is catalyzed by PdCl2(Me3P)2 to give the l,2-bis(siloxy)ethylene 121 in a good yield] 117]. Hydrosilylation of phenyl isocyanate (122) catalyzed by PdCT affords the N-... 

Detailed mechanistic studies with respect to the application of Speier s catalyst on the hydrosilylation of ethylene showed that the process proceeds according to the Chalk-Harrod mechanism and the rate-determining step is the isomerization of Pt(silyl)(alkyl) complex formed by the ethylene insertion into the Pt—H bond.613 In contrast to the platinum-catalyzed hydrosilylation, the complexes of the iron and cobalt triads (iron, ruthenium, osmium and cobalt, rhodium, iridium, respectively) catalyze dehydrogenative silylation competitively with hydrosilylation. Dehydrogenative silylation occurs via the formation of a complex with cr-alkyl and a-silylalkyl ligands ... 

Iridium complexes with O-donor ligand environments, Ir(triso)(ol)2 [triso = tris(diphenyloxophosphoranyl)methanide ol = C2H4, cyclooc-tene), catalyze the hydrosilylation and dehydrogenative silylation of ethylene with triphenylsilane.35 Diphenylmethylsilane can also be used in the... 

For example, the reaction of ethylene at 30°C yields both 1 and 2, but the major portion of the product mixture is due to hydrosilylation. At 80°C, a higher selectivity for double silylation was observed. Similar temperature dependence was observed in the reaction of oct-l-ene, although formation of 1 is never observed. In contrast, the major pathway for reaction of styrene is 1,1-double silylation, independent of temperature. In general, internal olefins do not react with o-bis(dimethylsilyl)benzene even on heating of the reaction mixture, possibly as a result of steric hindrance. However, 1,2-double silylation does occur for the double bond of dimethyl maleate, which is presumably activated by the two electronegative ethoxy groups. 

Ethylene coordinates too strongly to the ruthenium center to act as a hydrogen acceptor in this system, but slightly larger olefins do show activity. However, reaction selectivity is reduced compared with f-butyl ethylene. Thus, the use of cis and trans 2-pentene as hydrogen acceptor leads to products consisting of 90% carbosilane and 10% hydrosilylated olefin, and 1-hexene yields a carbosilane/hydrosilylation ratio of 4 6. In comparison, no hydrosilylation products are observed for dehydrocoupling in the presence of cyclohexene, but carbosilane formation is accompanied by disproportionation to benzene and cyclohexane as a side reaction. 

Pd(PPh3)4] (103) catalyzes the hydrosilylation of both ethylene and propylene chlorosilane.620 The same complex also catalyzes reaction (170).621... 

Hydrosilylation of hex-l-ene and ethylene with SiH4 occurs in the presence of LiAlH4 as a catalyst. A reaction mechanism involving SiH4 and the alkyl anion, generated by the initial interaction of the olefin with LiAlH4, has been proposed.62... 

The hydrosilylation-polymerization of 1,3-diethenyltetramethyldisiloxane (276) with 1,3-dihydrotetramethyldisiloxane (275) proceeds smoothly in the presence of Karstedt s catalyst to give high molecular weight poly[(l,l,3,3-tetramethyldisiloxanyl)ethylene] (277) (equation 104)273-274. 

Internal acetylenes, Ni-mediated reactions, 10, 546 Internal alkenes, ethylene co-polymers, 4, 1145 Internal alkynes in alder-ene reaction, 10, 567 intermolecular hydrosilylation with ruthenium, 10, 802 with yttrium, 10, 801 silylboration, 9, 163 silylformylation, 11, 483... 

PP-b-PMMA (Mn = 22220, Mw/Mn = 1.14) was produced by CRP via another route. Terminally vinyl PP (Mn = 3100, Mw/Mn = 1.45, isotactic-ity = 32%) prepared using a zirconocene catalyst was converted to terminally brominated PP via PP-SiH prepared by hydrosilylation [70]. The resulting PP-b-PMMA was purified by extraction of unreacted PP with diethyl ether. Poly(ethylene-co-butene)-bZocfc-poly(methyl methacrylate) (EBR-b-PMMA) was synthesized through the bromination of terminally hydroxy-lated EBR (Mw = 3600 g/mol, Mw/Mn = 1.05), which was commercially available [71]. An atactic PP/PMMA had been synthesized by a combination of metallocene catalyses, Cp2ZrCl2 and Me2Si(CpMe4)(.W-f-Bu)TiCl2, and ATRP [72]. 

Heterogcnized complexes have been used to catalyze a great number of reactions, such as hydrogenation [18], hydroformylation [19], ethylene oligomerization [20], hydrosilylation [21, 22], polymerization [23], telo-merization [24], oxidation [25], oligomerization of monoalkenc [26], methanol carbonylation [27], butadiene oligomerization [28], synthesis gas chemistry [29], and isomerization [30],... 

The first cyclolinear organosiloxane polymer with ethylene bridges between rings was synthesized by hydrosilylation of 1-hydro-3-vinylhexamethylcyclotetrasiloxane. 

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