Silane reaction products

Many filler materials are treated chemically to improve the adhesion between the filler and resin. The most widely known of these treatments are used on glass fibers and include silane reaction products and chromium complexes. Glass fibers are often flame treated. Several of the treatments are summarized in Table 3-3. Improved versions of these treatments have resulted in major improvements in the performance of fiber glass reinforced plastics so that a large fraction of the potential strength of these materials is realized in practice. 

The addition—reaction product of bisphenol A [80-05-07] and glycidyl methacrylate [106-91-2] is a compromise between epoxy and methacrylate resins (245). This BSI—GMA resin polymerizes through a free-radical induced covalent bonding of methacrylate rather than the epoxide reaction of epoxy resins (246). Mineral fillers coated with a silane coupling agent, which bond the powdered inorganic fillers chemically to the resin matrix, are incorporated into BSI—GMA monomer diluted with other methacrylate monomers to make it less viscous (245). A second monomer commonly used to make composites is urethane dimethacrylate [69766-88-7]. 

Kinetic hindrance of the silanization reaction due to high concentration of the reaction product, ethanol, in the compound... 

Nowadays silenes are well-known intermediates. A number of studies have been carried out to obtain more complex molecules having Si=C double bonds. Thus, an attempt has been made to generate and stabilize in a matrix 1,1-dimethyl-l-silabuta-l,3-diene [125], which can be formed as a primary product of pyrolysis of diallyldimethylsilane [126] (Korolev et al., 1985). However, when thermolysis was carried out at 750-800°C the absorptions of only two stable molecules, propene and 1,1-dimethylsilacyclobut-2-ene [127], were observed in the matrix IR spectra of the reaction products. At temperatures above 800°C both silane [126] and silacyclobutene [127] gave low-molecular hydrocarbons, methane, acetylene, ethylene and methylacetylene. A comparison of relative intensities of the IR... 

After dosing methyl radicals and chlorine molecules onto CuaSi samples which were cooled to 180 K, mass spectrometry was used to identify the gas phase reaction products upon heating. The silane products have been identified by monitoring their characteristic ions, which include SiCU" " (m/e=168), CHaSiCla (m/e=148), SiCla" " (m/e=133), (CHa)2SiCl2+ (m/e=128), CHaSiCl2+ (m/e=113), (CHa)2SiCl+ (m/e=93), SKCHala" " (m/e=73). All of these ions are detected. On the other hand, no CHaCl (m/e=53) or SiH4+ (m/e=32) are observed. 

Bowen, R. L. (1962). Dental filling material comprising vinyl silane treated fused silica and a binder consisting of a reaction product of bisphenol and glyddyl acrylate. US Patent 3,066,112. 

Not only the silane depletion, but also the hydrogen production can be used to obtain information on the reaction products of the decomposition process. In Figure 33 the silane depletion and the corresponding hydrogen production are shown for a number of experiments, with process parameters such as to cover both the a- and the y -regime [163, 301], A clear correlation exists. In addition. 

The incorporation of silyl substituents not only provides for specific reaction products but can also improve the effectiveness of polyene cyclization. For example, although cyclization of 2a gave a mixture containing at least 17 products, the allylic silane 2b gave a 79% yield of a 1 1 mixture of stereoisomers.13 This is presumably due to the enhanced reactivity and selectivity of the allylic silane. 

An asymmetric variant of this reaction was developed using chiral Pd complex 111 with either silanes or disiloxanes [66-68]. Both relative and absolute stereochemistries were controlled in this system and good yields (60-85%) were obtained after oxidation (Eq. 18). Formation of the silane-containing product was inhibited by the presence of water due to competitive formation of the palladium hydrides and silanols [68]. The use of disiloxanes as reductants, however, provided expedient oxidation to the alcohol products without decreasing the isolated yields enantioselectivity was 5-15% lower in this more robust system [66]. Benzhydryldimethylsilane proved to be a good compromise between high yield and facile oxidation [66]. Palladium com-... 

The most important process so far has been the reductive elimination of halogens with the formation of Si-Si bonds. Kipping used this reaction and discovered the first perphenylated cyclosilanes, yielding polysilanes as a by-product [8]. Similarly dodecamethylcyclohexasilane was found using dimethyldichlorosilane as a starting material for this reaction by Burkhardt in 1949, but 90% of the yield appeared as poly silane by-products [9]. 

Both materials were tested as catalysts in the anisole acylation (Scheme 1). The conventional Beta sample showed a slightly higher activity than the Beta (PHAPTMS). At 3 hours, the conversions were 26.8 and 22.8 % for the conventional and seed silanized catalysts, respectively. This behavior is explained as a consequence of the relatively small size of the anisole molecule, which allows this compound to diffuse without significant hindrances through the zeolitic micropores, and of the slightly weaker acidity of the Beta (PHAPTMS) sample. In both cases, p-methoxyacetophenone (p-MAP) was the main reaction product, being obtained with a high selectivity (> 97%). 

A mixture of exo- and endo-isomers of 5-methylbicylo[2.2.1]hept-2-ene is hydrogenated with the aid of five equivalents of triethylsilane and 13.1 equivalents of trifluoroacetic acid to produce a 45% yield of < <7o-2-methylbicylo[2.2.1] heptane (Eq. 71). The same product is formed in 37% yield after only five minutes. The remainder of the reaction products is a mixture of three isomeric secondary exo-methylbicylo[2.2.1]heptyl trifluoroacetates that remains inert to the reaction conditions. Use of triethylsilane-l-d gives the endo-2-methylbicylo-[2.2.1]heptane product with an exo-deuterium at the tertiary carbon position shared with the methyl group. This result reflects the nature of the internal carbocation rearrangements that precede capture by the silane.230... 

Dibenzyl Ether [Brpnsted Acid Promoted Reduction of an Aldehyde to a Symmetrical Ether].311 To a stirred solution of benzaldehyde (5.4 g, 0.05 mol) and TFA (11.4 g, 0.1 mol) under argon was added dropwise, with cooling, Et3SiH (8.1 g, 0.07 mol) at a rate such that the temperature of the reaction mixture did not exceed 40°. The solution turned a crimson color that gradually disappeared. Analysis by GLC showed the complete absence of the aldehyde immediately after addition of all of the silane. The products were separated by vacuum distillation at 20 Torr, collecting the fractions up to 125°. Dibenzyl ether was obtained from the residue by freezing out 4 g (0.02 mol, 80%) mp 3-6° nD25 1.5608. 

Recently, the silane-mediated reductive cyclization of activated alkynes with tethered ketones using Stryker s reagent as a catalyst was reported.112,90b Alkynyl ketone substrate 84a was treated with a catalytic amount of Stryker s reagent in the presence of polymethylhydrosiloxane (PMHS) to afford the cA-fused hydrindane 84b as a single diastereomer. This method is applicable to both five- and six-membered ring formation, but often suffers from competitive over-reduction of the reaction products (Scheme 59). 

Tamao et al,83 found that a higher coordinated silylene 119 can be formed from penta-coordinated silane 118 (Scheme 31). Warming a solution of 118 in toluene or dimethylformamide in the presence of diphenylacetylene or 2,3-dimethyl-l,3-butadiene resulted in the formation of silylene-trapping products 120 and 121. Interestingly, no 1 1 reaction product between the silylene and the acetylene was isolated. Thus, it must be concluded that the insertion of silylene 119 into a Si-C bond of initially formed silacyclopro-pene is faster than the addition to the triple bond of the acetylene so that the silacyclopropene cannot be isolated under the reaction conditions. 

It is important to note that catalysts for alkoxysilane hydrolysis are usually catalysts for condensation. In typical silane surface treatment applications, alkoxysilane reaction products are removed from equilibrium by phase separation and deposition of condensation products. The overall complexity of hydrolysis and condensation has not allowed simultaneous determination of the kinetics of silanol formation and reaction. Equilibrium data for silanol formation and condensation, until now, have not been reported. 

Abstract—The nature of the product of the reaction between an aminated silane and carbon dioxide was re-examined with the aid of simple model compounds, several amines, and several aminosilanes. Since the reaction products previously proposed include the amine bicarbonate and a carbamate derived from the amine, ammonium bicarbonate and ammonium carbamate were studied as models for the anions. Carbon dioxide adducts of neat model amines were prepared and studied. Results from a variety of techniques are summarized. Among the most useful was Fourier transform infrared (FTIR) spectroscopy of fluorolube mulls. FTIR spectra were distinctive and assignments characteristic of the two species were extracted from the spectral data. Comparisons of these assignments with the products of the reaction between carbon dioxide and various amines were made. The results indicate that alkylammonium carbamates are the principal product. Nuclear magnetic resonance (NMR) spectra in D20 indicated much dissociation and were not helpful in defining the products. 

It has also been shown that the Sakurai-Hosomi reaction of methallylsilanes with glyoxylates is catalyzed by the BINOL-Ti complex (1) to give the products, surprisingly, in an allylic silane (ene product) form with high enantioselecdvity (Scheme 8C.22) [53],... 

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