3- triethoxysilane

Vivekananda Bhatt Indian Institute of Science, Bangalore, India 

Solubility sol diethyl ether, THF, alkanes, aromatic and chlorinated solvents. 

Form Supplied in colorless liquid widely available. 

Handling, Storage, and Precautions is moisture sensitive and should be handled in a well-ventilated hood. Contact with the eyes and skin should be avoided. 

Robert J. R Corriu Christian Guerin Universite Montpellier II, France 

---

ZnCl2 is essential. The reaction was utilized in the synthesis of strophanthidin. Only the q, /3-alkene in the a, fi- and 7, (5-unsaturated ketone 51 is reduced selectively[47], Triethoxysilane is another reducing agent of the enone 52 and simple alkenes[48]. 

Nonlinear Optical Devices. A transparent, optically active, sol—gel-derived organic—inorganic glass has been synthesized (68). This hybrid consists of a 2,4-dinitroaminophenylpropyl-triethoxysilane covalently bound to a siUcon alkoxide-derived siUca network. This hybrid exhibits a strong electric field-induced second harmonic signal and showed no signs of crystallization. 

Use of HRh(CO)[P(CgH )2]3 as the catalyst and an excess of triphenylphosphine improves the y P ratio. For example, reaction of triethoxysilane with allylamine of equivalent moles at 150°C for 10 h, yields the y-form product ia more than 70% and the y P ratio is 26. Compared with this, when H2PtCl3 is used as the catalyst, the y P ratio is 4 (41). Furthermore, when Rh[(p.-P(C3H3)2-(cyclooctadiene)]2 is used as the catalyst, the yield of y-form product is selectively increased to 92% and that of P-form product is decreased to 1.1% (42). 

The reaction is of practical importance in the vulcanization of siUcone mbbers (see Rubber compounding). Linear hydroxy-terrninated polydimethyl siloxanes are conveniently cross-linked by reaction with methyldiethoxysilane or triethoxysilane [998-30-1]. Catalysts are amines, carboxyflc acid salts of divalent metals such as Zn, Sn, Pb, Fe, Ba, and Ca, and organotin compounds. Hydroxy-terrninated polysiloxanes react with Si—H-containing polysiloxanes to... 

The synthesis of triethoxysilane (28) and trimethoxysilane (29) has also been achieved by direct process. In 1980 there were no direct processes for the production of alkoxysilanes. In 1995 Silbond in Weston, Michigan, and Carboline in St. Louis, Missouri, operated processes for the production of tetraethoxysilane in the United States, and OSi/Witco announced start-up of a process to produce triethoxysilane and tetraethoxysilane in TermoH, Italy. 

The two best selectors resulting from Li s screening, DNB-L-ala and DNB-L-leu, were then prepared on a larger scale, attached to silica beads modified with 3-amino-propyl-triethoxysilane, and the CSPs were packed into columns. Respective separation factors of 4.7 and 12 were found for the separation of racemic naphthyl leucine ester 17 using these CSPs. 

The exocyclic C — C double bond in the chlorin can be reduced by catalytic hydrogenation in tetrahydrofuran/water in the presence of palladium(II) acetate with triethoxysilane as hydrogen source to yield under kinetic control cw-stereoisomers, which can be transformed by treatment with /)-toluenesulfonic acid in methanol to the thermodynamically favored trans-isomers.27d... 

Lee [242] studied the dependence of the physico-mechanical properties of Wollastonite-filled polychloroprene rubber on the type of agent used to pre-treat the filler. The composition contained 26.9 part (weight) of the filler per 100 parts (weight) of the rubber (compositions CR-1100, CR-174, CR-151). The finishing agents were y-aminopropyl triethoxysilane (CR-1100 and CR-174) and vinyl triethoxysilane (CR-151). The mechanical properties of the compositions are listed in Table 7 below. The author proposed an empirical equation to relate the modulus with the equilibrium work of adhesion in the following form ... 

In [276] the properties of kaolin-filled polyethylenes were investigated. The filler was pre-treated with silanes of two kinds, vinyl triethoxysilane (VTES) (I) and gamma-methacryloxypropyl trimethoxysilane (II). The results are presented in Table. 9. 

Chitosan membranes can also be superficially modified, for instance with 3-isocyanatopropyl triethoxysilane. Silanol groups and calcium salt acted as nucleation sites and accelerator, respectively, for the formation of apatite crystals therefore, this chitosan membrane is a bioactive guided bone-regeneration material thanks to its apatite-forming ability [341]. 

Recently Sahoo and Bhowmick [75] synthesized hydroxyl-terminated POSS in their laboratory starting from (3-aminopropyl) triethoxysilane (APS) and phenylglycidylether (PGE) and used it as a curative in carboxylated nitrile mbber (XNBR). This has been a newer class of material where the nanofiller simultaneously cures the mbber and promotes solvent resistance, as well as mechanical and dynamic mechanical properties. Table 3.3 illustrates some of these findings. 

The sol-gel technique was also used to prepare solid electrolytes containing MEEP, triethoxysilane (TEOS) and lithium triflate. Homogeneous, transparent and mechanicaUy stable materials have been obtained by Gughelmi [611] from a partially hydroxylated MEEP and TEOS, which after doping with LiSOjCFj exhibited a conductivity in the range 3x10 S cm at 60 °C. 

Rechavi and Lemaire reported the heterogeneization of copper bis(oxa-zoline) catalysts through covalent grafting onto silica via functionalization of indaBOX ligand by triethoxysilane groups [117] (84 in Scheme 47). 

Rh colloids were isolated during the hydrosilylation of trimethy(vinyl)silane with triethoxysilane using RhCl3 in EtOH as pre-catalyst. The colour changes observed during the catalytic reaction (from yellow, to red and black) are due to the formation of colloids as demonstrated by TEM this fact was in agreement with the catalytic activity behaviour observed [14]. 

This test was successfully applied for the hydrosilylat-ion of trimethyl(vinyl)silane by triethoxysilane catalysed by Rh or Pt colloids. The addition of mercury to catalytic mixture led to catalytic activity loss, consistent with a heterogeneous catalyst [12,14]. 

The compounds benzonitrile, p-methylbenzonitrile, /)-methoxybenzonitrile, p-trifluoromethyl-benzonitrile, /)-methoxycarbonylbenzonitrile, and triethoxysilane are commercial products and are degassed and stored under argon before use. Trimethylsilane was prepared according to a literature report [38]. The nitrile (9.8 mmol) and the hydrosilane (49 mmol) are added to the rhodium catalyst (0.1 mmol) contained in a Carius tube. When using trimethylsilane, the operation is performed at —20°C. The tube is closed and the mixture stirred at 100 °C for 15h. The liquid is separated by filtration and the excess of hydrosilane removed under vacuum to leave the N, Wdisilylamine derivative. If necessary, a bulb to bulb distillation is performed to obtain a completely colorless liquid. The yields obtained in the different runs are reported in Table 6. The product have been characterized by elemental analysis, NMR spectroscopy, and GC-MS analysis. 

The hydrogenation of alkenes and alkynes in water can also use silanes as hydrogen sources. Tour reported that by using palladium acetate as catalyst, triethoxysilane reduced C-C unsaturated bonds to saturation in a mixture of THF and water.18 The reaction showed excellent chemo- and stereoselectivity. Water was essential to the reaction. In the absence of water, 95% of the starting alkene remained unchanged (Eq. 3.3). 

Although the reaction scheme shows a complete hydrolysis before condensation begins, this is likely not correct as stated earlier. The relative rates and extents of these two reactions will particularly depend on the amount of water added and the acidity of the system (10,11). The high functionality of the triethoxysilane endcapped PTMO oligomer should enhance the incorporation of PTMO molecules into the TEOS network. It was also assumed that the reactivities would be the same between silanol groups from silicic acid and endcapped PTMO. Therefore, no preferential condensation was expected and the deciding factors for which type of condensation (self- or co-) took place would be the diffusivities and local concentrations. 

Table IV lists the mechanical stress-strain data for a series of hybrid TEOS-PTMO materials containing different levels of Ti-isop in the starting reaction mixture. These materials, with the exception of the first one, were all made using a modified reaction scheme (see experimental section) in order to incorporate the titanium into the network. The starting reaction mixtures in all cases contained 50% by weight of the glass precursors (TEOS and Ti-isop) and 50% by weight of PTMO(2000) (endcapped with triethoxysilane). One set of samples without titanium was made in order to compare the effects of the reaction scheme on the observed mechanical properties.

Hybrid materials with TEOS and triethoxysilane encapped PTMO have been successfully prepared by the sol-gel process. High transparency is observed for most samples, and many of the mechanical properties are considerably improved relative to the earlier reported TEOS-PDMS systems. 

---