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The hydrosilylation of alkynes is a powerful process for producing vinylsilane compounds, which are synthetically versatile organosilicon reagents in organic chemistry. Herein, atomically dispersed Au anchored on g-C3N4 nanosheets is developed as a superior catalyst for the alkyne hydrosilylation reaction. The atomic Au species are in the +1 oxidative state coordinating with three nitrogen atoms observed via X-ray absorption fine structure (XAFS) characterization and analysis. Aromatic alkynes and aliphatic alkynes with various functional groups can effectively produce corresponding β-(E)-vinylsilane products with high conversion and selectivity. The atomically dispersed Au catalyst could be reused at least for five cycles without obvious decline in activity and selectivity. The unique structural and electronic characteristic of AuI–N3 sites are conducive to the successive activation of Si–H bonds, which boost the superior activity and selectivity of the single atom site Au in alkyne hydrosilylation.

International audience; Commercially available Ni(II) and Co(II) complexes – M(acac)2 (acac = acetylacetonate) and M(tmhd)2 (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionato) – exhibit catalytic activity for alkene/vinylsilane dehydrogenative silylation (DS) and hydrosilylation (HS) with tertiary silanes without the use of any external reducing agents. Using the model compounds divinyltetramethylsiloxane a.k.a dvtms and vinylpentamethyldisiloxane a.k.a vpmds, different selectivities (HS, DS, undesired non-C–Si bond-forming reactions…) are observed whether nickel or cobalt catalysts are employed, with Ni being DS-selective and Co yielding bothHS and DS products. All four complexes are efficient at thermally inducing silicone-oil crosslinking under a non-inert atmosphere, and promote metal-dependent selectivity that is slightly different from model reactions, which HR-MAS NMR spectroscopy unveils. Additional observations as well as NMR studies of [Ni(tmhd)2 + reagent] mixtures provide some insights into the possible activation pathways.

The selective, intermolecular, homodimerization and cross-cycloaddition of vinylsilanes with unbiased 1,3-dienes, catalyzed by a pyridine-2,6-diimine (PDI) iron complex is described. In the absence of a diene coupling partner, vinylsilane hydroalkenylation products were obtained chemoselectively with unusual head-to-head regioselectivity (up to >98% purity, 98:2 E/Z). In the presence of a 4- or 2-substituted diene coupling partner, under otherwise identical reaction conditions, formation of value-added [2+2]- and [4+2]-cycloadducts, respectively, was observed. The chemoselectivity profile was distinct from that observed for analogous α-olefin dimerization and cross-reactions with 1,3-dienes. Mechanistic studies conducted with well-defined, single-component precatalysts ((Me)PDI)Fe(L(2)) (where (Me)PDI = 2,6-(2,6-Me(2)-C(6)H(3)N═CMe)(2)C(5)H(3)N; L(2) = butadiene or 2(N(2))) provided insights into the kinetic and thermodynamic factors contributing to the substrate-controlled regioselectivity for both the homodimerization and cross cycloadditions. Diamagnetic iron diene and paramagnetic iron olefin complexes were identified as catalyst resting states, were characterized by in situ NMR and Mössbauer spectroscopic studies, and were corroborated with DFT calculations. Stoichiometric reactions and computational models provided evidence for a common mechanistic regime where competing steric and orbital-symmetry requirements dictate the regioselectivity of oxidative cyclization. Although distinct chemoselectivity profiles were observed in cross-cycloadditions with the vinylsilane congeners of α-olefins, these products arose from metallacycles with the same connectivity. The silyl substituents ultimately governed the relative rates of β-H elimination and C–C reductive elimination to dictate final product formation.

A set of iridium(I) complexes of formula IrCl(κC,η2-IRCouR′)(cod) or IrCl(κC, η2-BzIRCouR′)(cod) (cod = 1,5-cyclooctadiene; Cou = coumarin; I = imidazolin-2-carbene; BzI = benzimidazolin-2-carbene) have beeen prepared from the corresponding azolium salt and [Ir(μ-OMe)(cod)]2 in THF at room temperature. The crystalline structures of 4b and 5b show a distorted trigonal bipyramidal configuration in the solid state with a coordinated coumarin moiety. In contrast, an equilibrium between this pentacoordinated structure and the related square planar isomer is observed in solution as a consequence of the hemilability of the pyrone ring. Characterization of both species by NMR was achieved at the low and high temperature limits, respectively. In addition, the thermodynamic parameters of the equilibrium, ΔHR and ΔSR, were obtained by VT 1H NMR spectroscopy and fall in the range 22–33 kJ mol−1 and 72–113 J mol−1 K−1, respectively. Carbonylation of IrCl(κC,η2-BzITolCou7,8-Me2)(cod) resulted in the formation of a bis-CO derivative showing no hemilabile behaviour. The newly synthesised complexes efficiently catalyze the hydrosilylation of alkynes at room temperature with a preference for the β-(Z) vinylsilane isomer.

The functionalization of polysilanes is an important subject in materials science because functionalized polysilanes are expected to exhibit potentially innovative properties. This research aims at the addition of a water-shedding property to polysilanes by introducing perfluoroalkyl groups into their skeleton. The photoinduced iodoperfluoroalkylation of various vinylsilanes takes place successfully upon irradiation with a xenon lamp: vinylmonosilanes undergo iodoperfluoroalkylation with perfluoroalkyl iodides (RfI) regioselectively, and the corresponding perfluoroalkylated silanes are obtained in moderate to high yields. Detailed optimization of the photoinduced iodoperfluoroalkylation has been investigated to apply this method to the functionalization of polysilanes. Polysilanes having vinyl groups can be synthesized by the reductive coupling of dichlorovinylsilanes with samarium diiodide (SmI2) and samarium metal (Sm) upon irradiation with visible light. The synthesized vinylpolysilanes and RfI (about 1.0 mM CHCl3 solution) are coated on a glass plate sequentially, and then the following photoirradiation with light of a wavelength over 300 nm successfully adds an excellent water-shedding property to the glass plate.

The application of 1,3-divinyl-1,3-dimethyl-1,3-diferrocenyldisiloxane [(CH2═CH)FcMeSi]2O (1) as an efficient electroactive vinylsilane precursor for thiol–ene radical reactions is described. In order to determine if steric or electronic limitations due to the redox-active metallocene moiety might affect the bis(hydrothiolation) of the bifunctional vinylsilane, a model reaction was initially performed between 1 and 2-mercaptoethanol, resulting in the formation of the newly sulfur-containing carbosiloxane 2 in excellent yield. The bis(thiol–ene) reaction of 1 was successfully extended to 2,2′-(ethylenedioxy)diethanethiol, affording a series of novel precisely defined, redox-active oxathiacrown macrocycles (3 and 4n) and sulfur-bearing linear oligo-carbosiloxanes (5n and 6n) with a backbone in which the −S(CH2)2–O(CH2)2O–(CH2)2S– chain and the −Si–O–Si– bond, bearing pendant ferrocenes, are alternately linked by ethylene bridges. These reactions have been initiated either thermally (in toluene solution with...

Oxide-supported rhodium catalysts with excellent activity in silylative coupling reactions have been developed. Reductive pretreatment of the catalysts in the presence of 0.5 equiv triphenylphosphine under a hydrogen atmosphere enhanced and stabilized the catalytic activity. Of the catalysts examined, ceria-supported rhodium had the highest activity in the homo-coupling of vinylsilanes to bis(silyl)ethenes at 170 °C. A zirconia-supported catalyst selectively gave E-1-aryl-2-silylethenes by cross-coupling of vinylsilanes with styrenes at 130 °C, and a high turnover frequency of >8200 h−1 was achieved at 170 °C. Spectroscopic studies revealed that well-dispersed surface rhodium(I) species predominantly formed on ceria or zirconia were transformed into rhodium hydride species, which are believed to be responsible for the high activity. These catalysts were recyclable without loss of activity, and leaching of rhodium species from the catalysts was not observed.

A new method for introducing robustly bound organic functional groups on silica surfaces is developed. Compared to conventional monomer immobilization procedures, the new vinylsilane-impregnated polymer based protocol can be employed for the preparation of various organic group functionalized silicas that are stable under both acidic and basic conditions. Organic functional groups can be readily introduced by one-step Rh(I)-catalyzed hydroacylation reaction or appended by Suzuki coupling reactions.

A new ruthenium complex catalyzed procedure for the efficient O -silylation of an SiO–H group on the silica surface of glass beads with controlled pores (CPG) using 1-trimethylsiloxy-3-dimethylvinylsilylpropane leading to Si–O–Si bond formation with the evolution of ethylene is described. The formed linker contains alkyl hydroxyl groups which can be reacted with a nucleoside phosphoramidite unit. The CPG support containing alkyl hydroxyl groups is successfully applied in automatic chemical synthesis of DNA fragments.

PurposeThe purpose of this paper is to improve the anti‐sedimentation of the acrylic resin containing long afterglow phosphors (SrMgAl4O8:Eu2+, Dy3+).Design/methodology/approachThe phosphors were first modified by the vinylsilane coupling agent MPS (3‐(methacryloxypropyl)‐trimethoxysilane). Then, the acrylic resin containing modified phosphors was synthesised by in situ polymerisation. Meanwhile, the compared blend sample was prepared by pure acylic resin with no modified phosphors in the same content. When the two resins were coated on glass, the films were characterised by ATR‐FTIR, SEM and TGA. The sedimentation performances of liquid resins were also observed.FindingsResults showed that anti‐sedimentation of acrylic resin with phosphors by in situ polymerisation was enhanced greatly, because the phosphors have been connected with the macromolecule chain, and dispersed homogeneously with no aggregation, so preventing its sedimentation.Research limitations/implicationsResearchers are encouraged to test the proposed method and enhance the anti‐sedimentation further.Practical implicationsThis method provides an idea to solve the problem of anti‐sedimentation in luminescent paint containing long afterglow phosphors in practical production and application.Originality/valueThis paper introduced the in situ polymerisation to enhance the anti‐sedimentation of acrylic resin containing long afterglow phosphors and it can be applied also to other inorganic powders.

Novel homocoupling reactions of vinylsilanes, catalyzed by a mixture of Ir(I) and HCl, were developed. This process leads to exclusive formation of head-to-tail vinylsilane dimers in high yields at room temperature. Synthetic attributes of transformations of the resulting head-to-tail vinylsilane dimers and polymerization of bis(vinylsilane) were investigated.

Compósitos de PP com fibras curtas de coco foram preparados em extrusora, com dois perfis de temperatura, visando avaliar o efeito compatibilizante de PP modificado com vinilalcoxisilano e com anidrido maleico. Foi verificado que os dois agentes de acoplamento melhoraram o módulo elástico, a tensão máxima e a resistência à absorção de água quando os materiais foram processados utilizando‑se um perfil de temperaturas mais elevadas. A morfologia dos compósitos também ficou mais homogênea na presença dos agentes de acoplamento, especialmente naqueles processados na temperatura mais alta. Esses resultados indicam que a temperatura é uma variável fundamental no estabelecimento das interações envolvendo os processos de compatibilização. PP composites filled with coir short fibers were prepared in an extruder using two temperature profiles. The objective was to evaluate the compatibilizing effect of PP modified with vinylsilane and with maleic anhydride. Both coupling agents improved elastic modulus, tensile strength and water absorption resistance when the materials were processed at the highest temperature profile. The composite morphology was more homogeneous in the presence of the coupling agents, mainly in the composites processed at the highest temperatures. These results indicate that temperature is a key variable for the establishment of the interactions involved in the coupling processes.

We synthesized new macromonomers containing vinylsilane moiety by cationic ring-opening polymerization of 2-ethyl-2-oxazoline. Kinetic studies proved that initiation with vinylsilane derivative, bearing chloride counterion, is a fast process followed by a slow propagation and absence of termination. We used the dispersion polymerization of styrene as test for the stabilizing efficiency of the newly synthesized macromonomer. The dispersion polymerization tests allowed the investigation of the effect of the macromonomer concentration on the number average diameter of the prepared polystyrene microspheres and its polydispersity index. In addition, we compared the stabilizing efficiency of commercial poly(N-vinylpyrollidone) with that of our macromonomer. Copolymerization of styrene with 10 wt% oxazoline macromonomer yielded stable and monodisperse microspheres, having the number average diameter of 1.8 μm and a good size polydispersity index of 1.05.

Structurally well-defined end-functionalized syndiotactic polystyrene (sPS) can be prepared by conducting a simultaneous selective chain transfer reaction during the syndiospecific polymerization of styrene in the presence of vinylsilanes. The production of vinylsilane end-capped sPS involves a unique selective chain transfer pathway via the incorporation of a terminal vinylsilane unit at the polymer chain end by 2,1-insertion. This unusual insertion pattern situates the bulky silyl functional group at a closer β-position from the active catalyst center, thus deactivating the propagating chain by a steric jam between the vinylsilane end group and the active catalyst. Subsequently, chain releasing by hydrogen addition (in the presence of H2) or by β-elimination (in the absence of H2) can take place, which leads to the production of end-functionalized sPS with precise controls of stereoregularity and of the location of functionality. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1690–1698, 2010

1,3-Diene-2,3-diyl diesters are synthesized by rhodium-catalyzed homocoupling of (1-acyloxyvinyl)silanes. Double transmetalation between vinylsilane and rhodium intermediate in a single catalytic cycle is the key in this reaction. From the homocoupling products, symmetrical α-diketone and its monoacetal are easily synthesized.

A series of novel oligomers with promesogenic groups on both termini were prepared by a hydrosilylation reac- tion between well-defined telechelic oligocarbosilazanes end-fitted with vinylsilane (SiVi) groups and promesogenic com- pounds containing one reactive hydrosilane (SiH) group. We investigated the correlations between the structure of the resulting mesogen end-capped oligomers and their phase behavior as examined by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM).

Radical (co)polymerization behavior of alkoxyvinylsilanes [tri(isobutoxy)vinylsilane 1, triethoxyvinylsilane 2, di(isobutoxy)methylvinylsilane 3, di(isobutoxy)phenylvinylsilane 4, diethoxymethylvinylsilane 5, and diethoxyphenylvinylsilane 6] was systematically investigated. Homopolymerization and copolymerization with styrene of these alkoxyvinylsilanes were performed under various conditions in order to find appropriate initiating systems for the radical polymerizations. Transformation of some of the copolymers into poly[(vinyl alcohol)-co-styrene]s was examined via oxidative cleavage of the Si-C bonds in the alkoxyvinylsilane repeating units.

Silaboration of 1,3-enynes catalyzed by group 10 metal complexes affords 1,3-dienes with vinylborane and vinylsilane functions or 1,2-dienes with allylborane and vinylsilane functions. The type of product formed is determined by the size of the alkyne substituent.

Syntheses of vinylsilyl alcohols having one to three vinyl moieties and their use as initiators for ethylene oxide polymerizations are discussed. Poly(ethylene oxide) oligomers with vinylsilanes at one end and a hydroxyl group at the other were prepared in base-catalyzed reactions. Molecular weights determined from 1H NMR and gel permeation chromatography were close to the targeted values. Carboxylic acid functional poly(ethylene oxide) oligomers were prepared from ene-thiol addition reactions of mercaptoacetic acid across the vinylsilane terminus. It is anticipated that these carboxylic acid functional oligomers will complex to magnetite nanoparticles to afford complexes that can be dispersed in aqueous media.

A new ruthenium complex-catalyzed O-silylation of silanols with vinylsilanes leading to siloxane bond formation with the evolution of ethylene is described. A maximum conversion of silanol is reached using an excess of vinylsilane to also yield the product of the homo -coupling of the latter. Under the optimum conditions, when vinylsilane with at least one ethoxy substituent is used, the reaction gives exclusively unsymmetrical siloxanes.

It has been demonstrated that peroxide-initiated grafting of vinylsilanes to polyethylene results in a nonuniform distribution of silane groups on the polymer chain due to a chain-transfer mechanism, leading to inefficient utilization of silane with respect to gel fraction in a crosslinked material. In this article, we demonstrate that grafting a nitroxyl free radical that contains a silane functional group gives a more uniform distribution of silane functionality. Model compounds were synthesized by grafting a silane-functionalized TEMPO derivative and a vinylsilane to cyclooc- tane, and their structures were compared. The product grafted with vinyltriethoxysi- lane consisted of essentially all multigrafted product with an average of 2.26 silane grafts per cyclooctane molecule, which is in close agreement with published data, while the product of grafting the silane-functional nitroxyl consisted of only the monografted species; no multigrafted product was detected. This confirms that graft- ing a silane-functionalized nitroxyl occurs via bimolecular combination of free radi- cals that is not affected by chain-transfer and suggests that the process may lead to more efficient utilization of silane as indicated by higher gel fraction for a given level of grafted silane. Synthetic work to prepare silane-functionalized TEMPO derivatives and preliminary studies to graft them to polyolefins are discussed. V

The reaction of α-chlorine-substituted allylsilanes with primary amines was promoted by CuCl to result in the selective formation of secondary amines bearing the vinylsilane functionality by a probable SN2′-allylation keeping the silyl group intact.

Fluoroalkanoyl peroxide [RF-C(=O)OO(O=)C-RF] decomposes homolytically through concerted three bond radical fission to afford fluoroalkyl radical (RF·) selectively, although the corresponding alkanoyl peroxide [R-C(=O)OO(O=)C-R] decomposes homolytically through stepwise radical fission to afford acyloxy radical [R-C(=O)O·] and alkyl radical [R·]. This decomposition of fluoroalkanoyl peroxide was applied to the direct fluoroalkylation of two end-sites of vinylsilane oligomers and (meth)acrylate oligomers. Fluoroalkyl end-capped trimethoxyvinylsilane oligomers [RF-(CH2CHSi(OMe)3)n-RF] thus obtained were applied to the surface modification on glass and traditional organic polymers such as PMMA and rubbers to exhibit not only strong hydrohobicity but good oleophobicity imparted by fluorine with extremely higher adhesive property on their surface. Fluoroalkyl end-capped actylate and methacrylate oligomers exhibited surface active properties imparted by fluorine, the same as for low-molecular weight fluorinated surfactants, and these fluorinated cooligomers formed the nanometer size-controlled self-assembled molecular aggregates in aqueous and organic media. These fluorinated molecular aggregates interacted with a variety of guest molecules such as low molecular biocides, fullerenes, and carbon nanotubes to afford the corresponding fluorinated oligomers/guest molecules nanocomposites. These fluorinated oligomers were applied to the preparation of fluorinated oligomers/silica gel nanocomposites and cross-linked fluorinated oligomeric nanoparticles.

Pd-catalyzed intra-molecular olefin insertion/carbonylation reaction of optically active α-alkenyl-α-acyloxysilanes is described. The reactions proceeded in a stereoselective manner to give five- and six-membered optically active carbocycles having (E)-vinylsilane in their side chains. Under CO condition, optically active carbocycles containing one-carbon homologated side chain were produced by Pd-catalyzed tandem olefin insertion–carbonylation reaction.

The reactivity of aminosilane and vinylsilane with a dihydroxy (Bisphenol AF) crosslinkable fluoroelastomer containing only vinylidene fluoride (VF2) and hexafluoropropylene (HFP) was monitored using Differential Scanning Calorimetry (DSC) and X-ray Photoelectron Spectroscopy (XPS). The DSC results showed that the introduction of an aminosilane, or a combination of aminosilane and vinylsilane solutions, to the cure system of the fluoroelastomer resulted in a peak shift. This shift indicates that crosslinking in fluoroelastomer-silane system occurs at a lower temperature when aminosilane is present. Results also confirm that the organofunctional group on the silane reacts with the elastomer. XPS analysis of the silane-coated fluoroelastomer heated at 120 °C, 160 °C and 200 °C reveals that dehydrofluorination of the polymer is one of the steps in the reaction. It is our hypothesis that the amine group on the aminosilane is a contributor to the dehydrofluorination of the fluoroelastomer.

Fluoroalkanoyl peroxide was reacted with 1,3-divinyltetramethyldisiloxane under very mild conditions to afford the fluoroalkyl end-capped vinylsilane oligomer containing vinyldimethylsiloxane segments. This fluoroalkyl end-capped vinylsilane oligomer was applied to the preparation of novel fluorinated block copolymers by the copolymerizations with traditional radical polymerizable monomers. It was demonstrated that these fluorinated block copolymers thus obtained can form the dendritic-type unimolecular micelles in aqueous solutions, and these fluorinated block copolymers were able to provide suitable host moieties to interact with fullerenes as guest molecules. Copyright © 2006 John Wiley & Sons, Ltd.

Silyl ethers can be produced from alcohols and vinyl-silanes under a rhodium(I) catalyst. The reaction is believed to proceed through an O-H bond cleavage of alcohol by rhodium(I) complex and a subsequent hydride insertion into vinylsilane followed by β-silyl elimination of the resulting β-silylethyl rhodium(III) complex.

The synthesis and characterization of octavinylsilsesquioxane (OVS)-based nanocomposite dendrimers with luminescent and charge transport properties are reported. The nanocomposite dendrimers were prepared in high yield using mild Heck chemistry of mono-haloaromatic compounds with the peripheral vinylsilane groups of OVS. Attachment of 2-naphthalene, 2-(9,9-dimethyl)fluorene, and 2-(4-phenyl)-5-(1-naphthyl)-1,3,4-oxadiazole resulted in materials with blue-violet emission (360–380 nm) and photo-luminescent quantum efficiencies (PLQEs) from 1 to 26%. Blue-green emission was observed for attachment of 1-pyrene, 9-anthracene, and N1-(4-phenyl)-N1,N4,N4-triphenylbenzene-1,4-diamine with PLQEs ranging from 23 to 50%. Despite the planar characteristics of the organic dendrons, the nanocomposite dendrimers are completely amorphous and have high glass transition temperatures (Tg) ranging from 115 to 186°C with decomposition temperatures (Td) exceeding 450°C. Matrix-assisted laser desorption ionization–time of flight shows that unlike traditional Heck chemistry, haloaromatic compounds are adding twice across the vinylsilane groups. Finally, organic light emitting diodes using the aromatic amine-based dendrimer as hole injection layers show 55% improvement in device efficiency over traditional materials (5.16 vs. 3.24 cd A−1) with brightness levels exceeding 40,000 cd m−2. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 157–168; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20080

Many efficient stereo- and regio-selective methodologies for synthesis of substituted vinylsilanes have been reported, involving mostly classical stoichiometric routes as well as, more recently, transition metal catalyzed transformations, in particular, hydrosilylation of alkynes and hydrogenation of silylalkynes. In the last two decades, two new reactions based on transformations of silicon derivatives catalyzed by transition metal complexes have been developed to provide universal routes for synthesis of well-defined molecular and macromolecular compounds with vinyl-silicon functionality commonly used in organic and polymer synthesis. These are the reactions of silylation of alkenes by hydrosilanes and by vinylsilanes. Since the synthetic aspects of these reactions have been recently discussed, this review is focused on the mechanism of homogeneous catalysis, i.e., the way of activation of Cvinyl H bond of alkenes as well as Si H and/or Si Cvinyl of silicon derivatives by late transition metal complexes both leading to vinyl-silicon containing compounds. The two reactions occur via the same active intermediates, i.e., late TM complexes involving M H and M Si bonds (where M is representative at iron- and cobalt-triades: for silylation by hydrosilane also nickel-triad). On the basis of experimental and theoretical studies of the reactivity, structure and catalytic activity of late transition metal complexes in the above mentioned reactions, particularly those reported in the last decade, generalized schemes for catalysis of both reactions have been proposed. The common crucial step of the two reactions catalyzed by complexes containing initially M H and/or M Si bond is an insertion of alkene into M Si bonds followed by β-H transfer to metal with elimination of substituted vinylsilane. In this case, a formation of M Si bond proceeds either via oxidative addition of hydrosilane (silylation by hydrosilane) or via insertion of vinylsilane into M H bond followed by β-Si transfer with evolution of ethylene (silylation by vinylsilane). Yet, if the catalysts contain initially no M H and M Si bond, their formation occurs via oxidative addition of hydrosilane (silylation by hydrosilane) or via preliminary oxidative addition of Cvinyl H of alkene to get M H bond, followed by insertion of vinylsilane to this bond and next β-Si transfer to metal with elimination of ethylene (silylation by vinylsilane).

The electrochemical synthesis and characterisation of poly(methyl vinylsilane) and a series of poly(methyl vinylsilane-co-metallocenes) network polymers are described in detail. This class of polymers are not accessible through Wurtz coupling reaction and are however prepared by electro-reduction of dichloro methyl vinylsilane in a non-aqueous system using aluminum electrodes in a single compartment cell. These polymers have been characterised using UV, FTIR, XRD, SEM and NMR spectral techniques. Cyclic voltammetric studies of the above polymers reveal their conducting behavior. These polymers show optical properties as explained from the results. Polymers of this type are proposed as potential soluble precursors for SiC and metal doped SiC materials.

[reaction: see text] A two-step approach that involves the synthesis of vinylsilane from allyl(isopropoxy)dimethylsilane (6) and the subsequent Pd-catalyzed cross-coupling of the resulting vinylsilane is applied in developing a novel diversity-oriented, three-component synthesis to homoallylic alcohols of common structure 1. Upon treatment of 6 with s-BuLi, the silylallylmetal 5 is generated and reacted with carbonyl compounds to produce functionalized vinylsilanes, which can couple with aryl/vinyl halides in the presence of palladium catalyst to afford 1.

New graft copolymer was prepared by incorporating tris(2-methoxyethoxy)vinylsilane (TMEVS) on ethylene-propylene-diene terpolymer (EPDM) by using dicumyl peroxide (DCP) as initiator, in Haake Rheocord 90 torque rheometer. The effect of EPDM concentration, TMEVS concentration, reaction time, reaction temperature and initiator concentration on the graft co polymerization was studied. The grafting efficiency of TMEVS on EPDM was confirmed by Fourier Transform infrared (FT-IR) spectroscopy. The grafting efficiency increased with increase in the silane concentration upto 6% by weight. The grafting efficiency decreased beyond 6% by weight due to homopolymerization of TMEVS and non-availability of carbon–carbon double bond in the EPDM terpolymer. The thermal properties of peroxide cured EPDM and hot water cured EPDM-g-TMEVS were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. The results show thermal properties like degradation tempertature and glass transition temperature of the EPDM-g-TMEVS were increased due to introduction of TMEVS on to EPDM terpolymer as well as the formation of thermally stable three-dimensional network. Copyright © 2004 John Wiley & Sons, Ltd.

The substitution of a carbon atom by silicon provides an attractive, novel approach to modification of the thermal stability and volatility of metal-organic chemical vapor deposition precursors supported by β-diketonate ancillary ligands. The low temperature reaction of the lithium enolates of acetyltrialkylsilanes with acyl chlorides affords the sila-β-diketones, R′C(O)CH2C(O)SiR3 (R′=Me, Et, n-Pr, i-Pr, n-Bu, i-Bu, s-Bu, t-Bu; SiR3=SiMe3, SiEt3, SiMe2(t-Bu), SiMe2(t-hexyl), Si(i-Pr)3), in good yields. Multinuclear NMR studies suggest that the sila-β-diketones exist as the enolic tautomer with a vinylsilane isomeric structure. Homoleptic Cu(II) sila-β-diketonate complexes were prepared in a first pass study to evaluate how precursor performance is affected by modulation of the peripheral substituents in the ligands. Thermal analyses, (TGA, DSC) show that the silylated Cu(II) precursors (SiR3=SiMe3; R′=t-Bu or i-Bu) have greater volatility than the corresponding carbon analogues. Some of the new Cu(II) complexes exist as liquids or low melting solids, which are preferred states for industrial deposition processes. X-ray diffraction studies of selected copper complexes showed them to have typical, square planar geometry; calculations of molecular volumes suggest that packing in the solid-state is less efficient for the silicon-containing complexes than for the non-silylated analogues.

Vinylsilane monomers (vinyltrimethoxysilane (VTMOS) and vinyltriethoxysilane (VTEOS)), methyl methacrylate (MMA), tert-butyl acrylate (tBA) and N-vinyl-2-pyrrolidone (VP) were used in the synthesis of functionalized vinyl copolymers. By using these monomers, VTMOS-co-MMA, tBA-co-VP and VTEOS-co-VP, with various compositions, were synthesized. The copolymers were characterized by viscometry, 1H-NMR, FTIR and elemental analysis. The monomer reactivity ratios were estimated by the Fineman–Ross and Kelen–Tudos linear procedures. These parameters were also estimated by using a computer program based on a non-linear minimization procedure known as Reactivity Ratios Error in Variables Model. Random copolymers and others containing blocks of one of the monomer units were obtained, depending on the chemical nature of the comonomers. The estimated comonomer sequence and distribution are discussed in terms of structural properties of the monomers such as molecular volume of the side groups, electronegativity of the substituents and steric hindrance. Analysis by comparison with other copolymers with analogous structures was also performed. Copyright © 2003 Society of Chemical Industry

Polypropylene (PP)/polyamide blends were compatibilized with PP modified with vinylsilane or maleic anhydride and ethylene–propylene random (EPR) copolymer modified with maleic anhydride. The thermal behavior, mechanical properties, and morphology of the blends were investigated. Thermal analysis showed that the polyamide crystallization temperatures shifted downward with all compatibilizers, whereas its melting behavior did not change. On the other hand, polypropylene crystallization temperatures shifted upward in all cases, except for blends containing EPR modified with maleic anhydride. Tensile strength and elongation at break increased for blends compatibilized with modified PP. Blends containing up to 7% of EPR modified with maleic anhydride did not show good yield stresses. The morphology of the blends showed a finer dispersion of the polyamide minor phase in the PP matrix. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2492–2498, 2003

A review, mainly of last 5 years, on the subject of fundamentals as well as technology of polyolefins' crosslinking with vinylalkoxysilanes (Fig. 1) on the background of other methods of such polymers' crosslinking. Threebase steps of this technology have been detaily presented, as follows: preparing of the polymer being able to crosslink (either by grafting of vinylsilane onto polyolefin or by copolymerization of olefin with vinylsilane), hydrolysis of alkoxysilane groups to silanol groups and condensation of the last ones with creation of -C-Si-O-Si-C- bonds connecting individual macromolecules. Thermal and mechanical properties of the products obtained this way (mainly all of PE-HD, PE-LD, PE-LLD and PP products) as well as their practical importance have been also described.

Novel siloxane tethered para divinylarene cyclophanes, containing phenyl, biphenyl and naphthalene rings as the aromatic nuclei, were prepared by the hydrolytic condensation of the corresponding bis{[dimethyl(i-propoxy)silyl]vinyl}arenes under basic conditions.The photophysics of the cyclophanes were investigated using UV and fluorescence spectroscopy.

A technique has been examined for reducing the extent of crosslinking resulting from 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane (L-231) initiating melt grafting of vinyltriethoxysilane (VTEOS) onto poly(ethylene-co-vinyl acetate) (EVA). Using measurements of crosslink density and VTEOS conversion, a standard of selectivity for the EVA/VTEOS/L-231 system at 145 °C was defined and used to assess the influence of a range of additives (0.25 mol per mole VTEOS). The data indicated that compounds such as 4-nonene, N,N-dimethylaniline, and cumene improve reaction selectivity, whereas dodecane and cyclohexyl acetate have no effect. A strong correlation between the minimum CH bond dissociation energy and the influence of a given compound is evident, suggesting that a labile CH bond is the key element of an effective additive. A mechanism of additive function on the basis of hydrogen atom donation is proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2397–2402, 2002

The ruthenium hydride complex-catalyzed N-silylation of primary and secondary amines with substituted vinylsilanes, with the general formula R(1)CH=CHSiR (where R(1) = H, Ph, n-Bu, Si(OEt)3), leading to the formation of a Si-N bond with the evolution of olefin is described. Vinylsilane acts as a silylative reagent and hydrogen acceptor. Under optimum conditions, the reaction offers an attractive route for the synthesis of silylamines. The preliminary mechanistic view of this novel general silylation reaction based on catalytic and deuterium labeling experiments, using NMR and GC-MS methods, confirm the synthetic observations.

Polymer-supported electrophilic halogenate(I) complexes 2 and 3 promote smooth addition to vinyl and allylsilanes without loss of the silyl group. In conjunction with Amberlyst A26 (OH− -form) vinyl silanes are converted into epoxysilanes. Fonds der Chemischen Industrie Novabiochem (Switzerland)

Nine new kinds of thermosetting polymers with the Si(H)CC unit were synthesized by dehydrogenative polycondensation reactions between hydrosilanes and diethynyl compounds in the presence of a magnesia catalyst. Phenylsilane, silane, vinylsilane, and n-octylsilane were used as the hydrosilanes, and 1,3-diethynylbenzene, 1,4-diethynylbenzene, 4,4′-diethynyldiphenyl ether, and 1,3-diethynyl-1,1,3,3-tetramethyldisiloxane were used as the diethynyl compounds. All the polymers were thermosetting, highly heat-resistant, easily soluble in a solvent, and moldable. In particular, Si(R)HCCC6H4CC (R = H or CHCH2) showed high thermal stability; the temperature of 5% weight loss was greater than 800 °C, and the residue at 1000 °C was over 90%. The thermal stabilities of the polymers were attributed to the crosslinking reaction of the SiH and CC bonds. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2658–2669, 2001

For controlling a reactive extrusion process in the subsequent study, the model equations of reaction kinetics and shear viscosity were studied. We focused on a free radical reaction between the molten polyethylene and vinylsilane. The kinetics model was expressed as a reaction rate equation with an apparent rate constant. The shear dependent of reacted polyethylene was formulated by employing the modified Cross model proposed in our early study. In addition, the average molecular weight was considered to correlate the shear viscosity with the reaction kinetics, leading to a series of rheo-kinetics formulas. The experiments were carried out in a specific batch mixer suitably designed for sampling in arbitrary periods. Their reaction conversions, molecular weight distributions, and shear viscosity were measured, respectively, with an induced coupled plasma (ICP) emission spectrochemical analyzer, a high temperature gel permeation chromatography (GPC), and a capillary rheometer. Determining the parameters in each model, a simulator is set to investigate an engineering extrusion process.

(Trimethylsilyl)ethylene-titanium alkoxide complex (1) was generated from trimethyl(vinyl)silane, Ti(O-i-Pr)(4), and i-PrMgCl as a preformed alkene-titanium complex and reacted with several unsaturated compounds such as aldehyde, imine, other vinylsilane, and acetylene to give the corresponding coupling products 4a-f, 6, 8, and 10a-d in a regioselective manner. Both of the two carbon-titanium bonds of the complex 1 reacted successively with esters to afford silylcyclopropanols 11a-j, 13, and 15, some synthetic applications of which were illustrated in the preparation of beta-silyl ketones 16 and cyclopropenes 17. Asymmetric addition of 1 to a chiral acyloxazolidinone 19 gave optically active cyclopropanol (+)-11a of 50% ee.

Peroxide initiated vinylsilane grafting of polypropylene in an intensive mixer, and the subsequent water crosslinking process were studied. Different concentrations of vinyl trimethoxysilane and dicumyl peroxide were used. The materials obtained after mixing in the rheocord were hot pressed at 190°C. The melt viscosity of the obtained sheets, the melting enthalpy and melting temperature (DSC, differential scanning calorimetry), the mechanical properties and the thermal decomposition behavior (TG, thermogravimetric analysis) were studied. No evidence of grafting during the rheocord processing was observed. Nevertheless, for the hot pressed sheets with concentrations higher than 4 phr of vinyl silane an important increase in the melt viscosity was observed. This increase agrees with the change observed in the mechanical properties, which show a maximum for the water crosslinked samples containing 4 phr of vinyl silane. The modulus increases by 39% at 90°C and 33% at 130°C, while the tensile strength rises by ∼22% at both temperatures. The silane grafted water crosslinked samples show a more stable thermal behavior than both the silane grafted samples and the unmodified polypropylene.

Functionalization of poly(ethylene-co-vinyl acetate) (EVA) with vinyltriethoxysilane (VTEOS) has been carried out by a free-radical melt-grafting procedure in the presence of added comonomers. The influence of comonomers on silane graft yield and crosslink density has been assessed. Experiments were performed on masterbatches of EVA, VTEOS (5 wt %), peroxide initiator (L-231, 0.05 wt %), and comonomer (0–1 comonomer : VTEOS mole ratio) prepared at 90°C. Melt-grafting experiments were carried out at 145°C in an oscillating disk rheometer (ODR), which measured crosslink density during the grafting process. Silane graft yields were determined by proton NMR spectroscopy. Comonomers evaluated were maleic anhydride (MAn), 1-vinyl-2-pyrrolidone (VP), and 1-dodecene (DD). At the comonomer ratios examined, MAn suppressed both silane grafting and peroxide-initiated crosslinking. Both VP and DD, however, exhibited greater selectivity in suppressing crosslinking than silane grafting; optimum performance was found at a comonomer : vinylsilane mole ratio of 0.2. None of the comonomers studied enhanced the level of silane grafting. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1308–1314, 2000

Polybutadiene (I) containing 91% 1,4-(cis/trans) units and 9% of 1,2 units, in the presence of vinyltriethoxysilane and ruthenium catalysts Cl2(PCy3)2Ru=CHPh (II) and [RuCl2(p-cymene)]2/N2CHSiMe3/PCy3 (III) at 60°C and at room temperature undergoes partial degradation and functionalization. At a ratio [vinylsilane]/[total >CC CC CC

Three methods have been employed in the synthesis of 2-trialkylsilylaziridines. Firstly, reacting α-chloro-α-silyl carbanions with imines. Secondly, from the corresponding vinylsilane, via addition of bromoazide to give the 1-bromo-2-azide, followed by reduction. Finally, by the addition of organoazides to vinylsilanes using thermochemical and photochemical conditions. Using these three strategies a range of substitution patterns have been achieved.