Silanes

Trialkylsilyl Blocking Agent Used as a protecting group for reactive hydrogens in alcohols, amines, thiols, and carboxylic acids. Organosilanes are hydrogen-like, can be introduced in high yield, and can be removed under selective conditions. They are stable over a wide range of reaction conditions and can be removed in the presence of other functional groups, including other protecting groups. The tolerance of silylated alcohols to chemical transformations summary is presented in Table 1 of the Silicon-Based Blocking Agents brochure. 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. Triisopropylsilane; Triisopropylsilylhydride; TIPS-H Silylates strong acids with loss of hydrogenSilylates 1° alcohols selectivelySteric bulk allows for selective silylation of compounds with more than one hydroxyl groupSummary of selective deprotection conditions is provided in Table 7 through Table 20 of the Silicon-Based Blocking Agents brochureVery sterically-hindered silaneBlocking agent forming derivatives stable in presence of Grignard reagentsSelectively silylates primary alcohols in presence of secondary alcoholsUsed as a cation scavenger in the deprotection of peptidesExtensive 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. 1,5-Dichlorohexamethyltrisiloxane; Hexamethyldichlorotrisiloxane; 1,5-Dichloro-1,1,3,3,5,5-hexamethyltrisiloxane ΔHvap: 47.7 kJ/molVapor pressure, 50 °C: 1 mm

2-(4-Pyridylethyl)triethoxysilane, 4-(triethoxysilyl)pyridine Monoamino functional trialkoxy silaneAmber liquidForms self-assembled layers which can be “nano-shaved” by scanning AFMUsed in microparticle surface modification

Fluoroalkyl 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. Nonafluorohexyltrimethoxysilane; (1H,1H,2H,2H-Perfluorohexyl)trimethoxysilane Viscosity: 2 cStImproves hydrolytic stability of dental compositesTrialkoxy silane

(N,N-Diethylaminomethyl)triethoxysilane; (3-(triethoxysilyl)methyl)diethylamine Tertiary amino functional trialkoxy silaneCatalyst for neutral cure 1-part RTVs

Tipped PEG Silane (438.68 g/mol) PEG3C11 Silane3,3-Dimethoxy-2,15,18,24-pentaoxa-3-silapentacosanePEO, Trimethoxysilane termination utilized for hydrophilic surface modificationPEGylation reagentHydrogen bonding hydrophilic silane

Specialty Silicon-Based Blocking Agent Used as a protecting group for reactive hydrogens in alcohols, amines, thiols, and carboxylic acids. Organosilanes are hydrogen-like, can be introduced in high yield, and can be removed under selective conditions. They are stable over a wide range of reaction conditions and can be removed in the presence of other functional groups, including other protecting groups. The tolerance of silylated alcohols to chemical transformations summary is presented in Table 1 of the Silicon-Based Blocking Agents brochure. Chloromethyldimethylchlorosilane; (Chlorodimethylsilyl)chloromethane; Chloro(chloromethyl)dimethylsilane; CMDMCS Can form cyclic products with appropriate 1,2-difunctional substratesUsed in analytical applications for greater ECD detectabilitySummary of selective deprotection conditions is provided in Table 7 through Table 20 of the Silicon-Based Blocking Agents brochure