Silanes
The simplest silicon hydride is silane (SiH4). This molecule provides the basis for silicon nomenclature. Silane has the general formula SinH2n+2 and contains Si-H single bonds. Typically, SiH4 is used as the starting material for all other silicon compounds that can be either linear or cyclic, where the general formula for cyclic compounds is (SinH2n, n>2).
The term silanes are also defined based on the substitution pattern of atoms that surround the central silicon atom. Such substitution can be a combination of almost any four organic or inorganic reactive or non-reactive atoms/groups. One such example is tetrachlorosilane, SiCl4, which is classified as a halosilane with a bonding structure of Si-X, where X is a halogen. A silane that contains at least one carbon-silicon bond (Si-C) is known as an organosilane such as trimethylsilane (CH3)3SiH. In addition to other compound classifications, some silanes can also be used as intermediates that react to produce silicates and siliconates.
When comparing Si-H to C-H bonds, C-H bonds are polarized towards carbon due to carbon being more electronegative than the hydrogen, however, silicon is more electropositive and changes the polarity of the bond towards the hydrogen. Thus, the resulting reactivity of the molecules is vastly different. First, due to the hydridic nature of the hydrogen, the reaction typically proceeds through an anti-Markovnikov addition to olefins when a catalyst is present. Second, nucleophilic reactions at Si center are typically easier than the equivalent molecule with a carbon center. Third, silicon has greater bond energies with more electronegative elements. Finally, Si-C bond can stabilize carbocations and carbanions in the beta position – also known as the beta silicon effect.
Proper handling of certain silanes demands careful awareness and understanding that water can have a huge impact on the successful use of the various silanes. In the presence of water, silanes can undergo irreversible hydrolysis, and they can react with themselves and any hydroxyl groups within an inorganic substrate. In some cases, proper Schlenk line technique or a glovebox is recommended for proper uses.
Applications
Various silanes provide reactive chemistry at interfaces to improve performance and durability of composites. They are ideal for high-performance paints, inks and coatings due to their unique properties. These compounds offer improved adhesion and filler dispersion, and provide water, stain, and chemical repellent properties to surfaces. In addition, the are also resistant to ultraviolet radiation and abrasion. These qualities make silanes an excellent choice for
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Coupling agents
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Adhesion promoters
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Hydrophobic and dispersing agents
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Moisture scavengers
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Silicate stabilizers and precursors
Coming Soon!!!
We offer custom synthesis of various silanes, and we will be providing a catalogue of compounds that will be readily available upon request.