Silanes

Tri-substituted Silane Reducing Agent Organosilanes are hydrocarbon-like and possess the ability to serve as both ionic and free-radical reducing agents. These reagents and their reaction by-products are safer and more easily handled and disposed than many other reducing agents. The metallic nature of silicon and its low electronegativity relative to hydrogen lead to polarization of the Si-H bond yielding a hydridic hydrogen and a milder reducing agent compared to aluminum-, boron-, and other metal-based hydrides. A summary of some key silane reductions are presented in Table 1 of the Silicon-Based Reducing Agents brochure. Triphenylsilane; Triphenylsilanlyl hydride More effective radical-based reagent for reduction of organic halides than the trialkylsilanesCompares well with tri-n-butyltin hydride in reduction of enones to ketonesShows good selectivity in the reduction of cyclic hemiacetalsConverts O-acetyl furanoses and pyranoses to deoxy sugarsExtensive review of silicon based reducing agents: Larson, G.; Fry, J. L. "Ionic and Organometallic-Catalyzed Organosilane Reductions", Wipf, P., Ed.; Wiley, 2007

Alkyl Silane - Conventional Surface Bonding Aliphatic, fluorinated aliphatic or substituted aromatic hydrocarbon substituents are the hydrophobic entities which enable silanes to induce surface hydrophobicity. The organic substitution of the silane must be non-polar. The hydrophobic effect of the organic substitution can be related to the free energy of transfer of hydrocarbon molecules from an aqueous phase to a homogeneous hydrocarbon phase. A successful hydrophobic coating must eliminate or mitigate hydrogen bonding and shield polar surfaces from interaction with water by creating a non-polar interphase. Although silane and silicone derived coatings are in general the most hydrophobic, they maintain a high degree of permeability to water vapor. This allows coatings to breathe and reduce deterioration at the coating interface associated with entrapped water. Since ions are not transported through non-polar silane and silicone coatings, they offer protection to composite structures ranging from pigmented coatings to rebar reinforced concrete. A selection guide for hydrophobic silanes can be found on pages 22-31 of the Hydrophobicity, Hydrophilicity and Silane Surface Modification brochure. Dimethyldiacetoxysilane; Diacetoxydimethylsilane Reagent for the preparation of cis-diols and corticosteroids

Bis[m-(2-triethoxysilylethyl)tolyl]polysulfide Sulfur functional dipodal silaneDark, viscous liquid Coupling agent for styrene-butadiene rubber, SBR

Aromatic Silane - Conventional Surface Bonding Aliphatic, fluorinated aliphatic or substituted aromatic hydrocarbon substituents are the hydrophobic entities which enable silanes to induce surface hydrophobicity. The organic substitution of the silane must be non-polar. The hydrophobic effect of the organic substitution can be related to the free energy of transfer of hydrocarbon molecules from an aqueous phase to a homogeneous hydrocarbon phase. A successful hydrophobic coating must eliminate or mitigate hydrogen bonding and shield polar surfaces from interaction with water by creating a non-polar interphase. Although silane and silicone derived coatings are in general the most hydrophobic, they maintain a high degree of permeability to water vapor. This allows coatings to breathe and reduce deterioration at the coating interface associated with entrapped water. Since ions are not transported through non-polar silane and silicone coatings, they offer protection to composite structures ranging from pigmented coatings to rebar reinforced concrete. A selection guide for hydrophobic silanes can be found on pages 22-31 of the Hydrophobicity, Hydrophilicity and Silane Surface Modification brochure. Phenethyldimethyl(dimethylamino)silane; N,N,1,1-Tetramethyl-1-(2-phenylethyl)silanamine; N,N,1,1-Tetramethyl-1-(2-phenylethyl)-silanamine Contains 10-15% α-isomer

N,N-didecyl-N-methyl-N-(3-trimethoxysilylpropyl)ammonium chloride; (trimethoxysilylpropyl)didecylmethylammonium chloride; didecylmethyl[3-(trimethoxysilyl)propyl]ammonium chloride Quaternary amino functional trialkoxy silaneIn combination with TEOS (SIT7110.0), forms high pore volume xerogels with adsorptive capacityContains 3-5% Cl(CH2)3Si(OMe)340-42% in methanol

Olefin Functional Alkoxy Silane Silane coupling agents have the ability to form a durable bond between organic and inorganic materials to generate desired heterogeneous environments or to incorporate the bulk properties of different phases into a uniform composite structure. The general formula has two classes of functionality. The hydrolyzable group forms stable condensation products with siliceous surfaces and other oxides such as those of aluminum, zirconium, tin, titanium, and nickel. The organofunctional group alters the wetting or adhesion characteristics of the substrate, utilizes the substrate to catalyze chemical transformations at the heterogeneous interface, orders the interfacial region, or modifies its partition characteristics, and significantly effects the covalent bond between organic and inorganic materials. Dipodal Silane Dipodal silanes are a series of adhesion promoters that have intrinsic hydrolytic stabilities up to ~10,000 times greater than conventional silanes and are used in applications such as plastic optics, multilayer printed circuit boards and as adhesive primers for ferrous and nonferrous metals. They have the ability to form up to six bonds to a substrate compared to conventional silanes with the ability to form only three bonds to a substrate. Many conventional coupling agents are frequently used in combination with 10-40% of a non-functional dipodal silane, where the conventional coupling agent provides the appropriate functionality for the application, and the non-functional dipodal silane provides increased durability. Dipodal silanes additives enhance hydrolytic stability, which impacts on increased product shelf life, ensures better substrate bonding and also leads to improved mechanical properties in coatings as well as composite applications. 1,2-Bis(triethoxysilyl)ethylene; 4,4,7,7-Tetraethoxy-3,8-dioxa-4,7-disiladec-5-ene ~80% trans isomerForms ethylene-bridged mesoporous silicas