Silane Reagents & Coupling Agents
High-purity organosilane compounds for surface modification, polymer coupling, protective silylation, and advanced synthesis. Engineered for precision in research and industrial applications.
Shop Silane Products →Why Choose UCT Silanes?
UCT’s Petrarch® Specialty Chemicals line offers high-purity organosilane reagents for coupling, blocking, derivatization, and advanced synthesis — versatile compounds that bridge organic and inorganic materials at the molecular level.
Organosilanes are monomeric compounds containing at least one silicon-carbon bond — the essential building blocks used as coupling agents, blocking agents, derivatization reagents, and synthetic intermediates across industries ranging from composite manufacturing to pharmaceutical synthesis to semiconductor fabrication. Unlike silicones (which are polymers with repeating Si-O backbones), silanes are discrete small molecules with precisely defined reactivity, making them ideal for targeted surface modification, functional group protection, and molecular bridging between organic and inorganic materials. All organosilane products ultimately trace back to silicon dioxide — the most abundant compound in the earth’s crust — which is refined to silicon metal and then converted to the chlorosilane precursors that serve as starting materials for the entire product family. The chemistry of organosilanes has been studied systematically since the work of Frederick S. Kipping at the University of Nottingham (1898–1939), honored today by the American Chemical Society’s biannual Kipping Award. UCT manufactures and supplies a comprehensive catalog of high-purity silane reagents through the Petrarch® Specialty Chemicals line — acquired in 1993 specifically to expand UCT’s capabilities in specialty silane synthesis — with products packaged to order from 5 grams to 55 gallon drums.
Coupling Agents
Organosilanes with dual functionality — a hydrolyzable group that bonds to inorganic substrates and an organic group that bonds to polymer matrices — for dramatically improved adhesion in composites.
Blocking Agents
Silylating reagents that protect hydroxyl, amine, thiol, and carboxyl groups during synthetic sequences, with selectivity and stability tunable by steric bulk.
Synthesis Reagents
Hydrosilylation catalysts, reductive silylation agents, and functionalized monomers for building silicon-carbon bonds and custom organosilicon architectures.
Analytical Derivatization
Silylating agents for GC analysis — converting alcohols, acids, amines, and carbohydrates to volatile trimethylsilyl derivatives with improved chromatographic behavior.
Silane Blocking & Protecting Groups
Silyl groups protect reactive functionalities during chemical and synthetic sequences, with selectivity and hydrolytic stability controlled by steric bulk.
Silyl blocking groups have long been employed to derivatize and protect various substrates during synthetic sequences. Replacing active hydrogen atoms with silyl groups affords products that are more chemically stable and undergo subsequent reactions at other sites. Both blocking and deblocking reactions are typically high-yield — often quantitative — which has led to the development of a wide range of specialty blocking agents designed for specific purposes: selectivity for particular functional groups, degree of reactivity for less reactive substrates, nature of the silylation byproduct for sensitive substrates, and stability of the blocked intermediate toward other reagents. UCT offers blocking agents ranging from the standard trimethylsilyl (TMS) group through increasingly hindered groups — triethylsilyl, phenyldimethylsilyl, t-butyldimethylsilyl (TBDMS), triisopropylsilyl (TIPS), and t-butyldiphenylsilyl (TBDPS) — as well as difunctional blocking agents for cyclosilylation of vicinal diols and primary amines. Many of these protecting group silanes are also available through UCT’s Selectra-Sil DR product line.
Trimethylsilyl (TMS) Group
T2950 · H7300 · B2500 · B2570 · T3600The most common blocking group, introduced via trimethylchlorosilane (T2950), hexamethyldisilazane (H7300), or the more powerful bis(trimethylsilyl)acetamide (B2500). Readily removed through acidic or basic hydrolysis. H7300 combined with T2950 in a 2:1 weight ratio rapidly silylates three molar equivalents of substrate with ammonium chloride as the byproduct. Trimethylsilylimidazole (T3600) is specific for hydroxyl groups and will not silylate amines.
t-Butyldimethylsilyl (TBDMS) Group
B2790Relatively stable against deblocking in weakly acidic or basic media, mild oxidizing and reducing conditions. Unaffected by hydrogenolysis over palladium and lithium aluminum hydride, and stable to Grignard reagents. A major factor in developing syntheses of prostaglandins, with extensive use in terpenoid and carbohydrate chemistry. Derivatization is achieved with B2790 in the presence of imidazole using DMF as solvent. Removed with tetrabutylammonium fluoride in THF.
Triisopropylsilyl (TIPS) Group
T2885Provides hydrolytic stability intermediate between TBDMS and TBDPS derivatives under acidic conditions, and greater stability than both under basic conditions. TIPS derivatives of primary and secondary alcohols show different reactivity, allowing selective silylation and desilylation of multifunctional compounds — particularly useful in nucleoside and nucleotide chemistry.
t-Butyldiphenylsilyl (TBDPS) Group
B2805Provides the highest stability of the monofunctional blocking groups. Hydroxyl derivatives are stable to 80% acetic acid (which cleaves TBDMS), 50% aqueous trifluoroacetic acid-dioxane, hydrogenation over Pd, Grignard reagents, and lithium aluminum hydride. Very resistant to hydrolysis and oxidation. Removed with tetrabutylammonium fluoride in THF.
Difunctional Blocking Agents (Cyclosilylation)
D5490 · D5600 · D4368 · T2015Difunctional agents selectively block primary amines, vicinal diols, or other suitable difunctional sites by forming five-, six-, or seven-membered silicon-containing rings that are very stable to hydrolysis, oxidation, and reduction. Dimethyldiacetoxysilane (D5490) and dimethyldimethoxysilane (D5600) are effective for rigid molecules like steroids. 1,3-Dichlorotetraisopropyldisiloxane (D4368) simultaneously protects the 3′- and 5′-hydroxy groups in nucleosides, allowing selective reaction at the 2′-position. 1,1,4,4-Tetramethyl-1,4-dichlorodisilethylene (T2015) protects primary amines with derivatives stable to strong bases and oxidizing agents.
Silane Coupling Agent Chemistry
Coupling agents form a molecular bridge between organic polymers and inorganic substrates, dramatically improving adhesion, mechanical strength, and environmental durability.
The general formula of an organosilane coupling agent is RnSiX(4-n), where X is a hydrolyzable group (typically methoxy or ethoxy) involved in bonding to the inorganic substrate, and R is a non-hydrolyzable organic radical with functionality that enables bonding to the organic polymer matrix. During application, the alkoxy groups hydrolyze to form reactive silanols, which condense with hydroxyl groups on siliceous surfaces to form covalent siloxane (Si-O-Si) linkages. Stable condensation products also form with oxides of aluminum, zirconium, tin, titanium, and nickel. The silane coupling mechanism proceeds in four steps: hydrolysis of the labile X groups, condensation to oligomers, hydrogen bonding with substrate hydroxyl groups, and finally covalent bond formation during drying or curing. Most siliceous substrates have 4–12 silanols per nm², and for most fillers a treatment level of 0.02–1.0% by weight is used. Silanes with three hydrolyzable groups provide maximum hydrolytic stability but tend to be hygroscopic, while mono-functional silanes yield the most hydrophobic interfaces. Contact your local UCT sales representative for help selecting the optimal coupling agent.
| Polymer / Resin System | Recommended Silane Classes | Example UCT Products |
|---|---|---|
| Epoxy | Amine, Epoxy, Chloroalkyl, Mercapto | A0700, A0750, T2910, G6720, E6250, C3300, M8450, M8500 |
| Polyester | Amine, Methacrylate, Styryl, Vinyl | A0700, A0750, T2910, M8550, S1590, V4917, V4910 |
| Polyurethane | Amine, Alkanolamine, Epoxy, Isocyanate | A0700, A0750, T2910, B2408, G6720, E6250, I7840 |
| Polyamide (Nylon) | Amine, Ureido | A0700, A0742, A0750, PS076, T2910, T2507 |
| Polypropylene | Aromatic, Styryl | P0320, P0330, S1590 |
| Polycarbonate | Amine | A0700, A0750, T2910 |
| Phenolic | Amine, Chloroalkyl, Epoxy | A0700, A0750, T2910, C3300, G6720, E6250 |
| Silicone Rubber | Amine, Allyl | A0700, A0750, A0567 |
| Polysulfide Sealants | Mercapto, Amine | B2494, M8500, M8450, A0699, A0700, A0742, A0750, T2910 |
| Polyethylene | Amine, Styryl, Vinyl | A0700, A0750, A0742, V4910, V4917, S1590 |
Silylation & Application Methods
Practical guidance on silylation of molecular species and surface treatment with silane coupling agents.
Silylation is the replacement of an active hydrogen with a substituted silicon atom. For molecular species, this is performed to produce blocked intermediates for synthesis or volatile derivatives for GC analysis. For macromolecular structures, functional silane groups are applied to impart specific surface properties — wettability, surface energy, adhesion, and covalent reactivity. The most widely used reagents employ the trimethylsilyl group (Me₃Si–), while increased hydrolytic stability is available with bulkier groups such as phenyldimethylsilyl, t-butyldimethylsilyl, and triisopropylsilyl. For coupling agent applications, deposition from aqueous alcohol solutions is the most common method: a 2% silane concentration in 95% ethanol / 5% water adjusted to pH 4.5–5.5 with acetic acid, with cure at 110°C for 5–10 minutes or 24 hours at room temperature. Aminofunctional silanes (A0700, A0750) do not require additional acid.
Molecular Silylation Methods
- Chlorosilane/Base: 20% molar excess of silane and base (triethylamine, pyridine, or imidazole for TBDMS). Room temperature to 2-hour reflux.
- HMDS (H7300): 0.6 molar equivalent neat or in solvent. Reflux until ammonia evolution ceases. Add catalytic H₂SO₄ or 10% T2950 for less reactive substrates.
- Silylamides (B2500/B2570): Slight molar excess in DMF or acetonitrile. Complete in 5 min at 65–70°C or 20–30 min at room temperature. Most powerful TMS donors.
- Silylimidazole (T3600): Specific for hydroxyl groups — will not silylate amines. Rapidly blocks hindered alcohols in steroids and is very effective for complete blocking of sugars.
Coupling Agent Deposition Methods
- Aqueous Alcohol: 2% silane in 95% ethanol / 5% water, pH 4.5–5.5. Dip 1–2 min, rinse with ethanol, cure 110°C for 5–10 min. Deposits 3–8 molecular layers.
- Aqueous Solution: 0.5–2% in water (add 0.1% nonionic surfactant for less soluble silanes). Spray or dip, cure 110–120°C for 20–30 min.
- Bulk Powder Treatment: 25% in alcohol, sprayed into high-intensity mixer with the substrate. Complete within 20 min. Dynamic drying most effective.
- Integral Blend: 0.2–1.0 wt% silane added to dry-blend of polymer and filler before melt compounding. Vacuum devolatilization required.
- Primer Deposition: 50% in alcohol with 1–3 equivalents water, equilibrate 15–20 min, dilute to 10%, cure 110–120°C for 30–45 min.
Infrared Spectra-Structure Correlations
Characteristic infrared absorption frequencies for identifying organosilicon functional groups in research and QC applications.
The infrared spectrum reveals vibrations of atoms in molecules, and certain groups have characteristic frequencies that persist across different compounds. For organosilicon chemistry, IR spectroscopy is an indispensable tool — the Si-CH₃ group is easily recognized by a strong, sharp band at about 1260 cm⁻¹ together with strong bands in the 865–750 cm⁻¹ range, while Si-H shows a distinctive strong band at 2280–2080 cm⁻¹ with virtually no interference from other absorptions. These correlations are most accurate for liquids or solutions; crystalline solids may show shifts and splitting compared to liquid-state spectra, though non-crystalline solids (amorphous polymers, glasses) tend to have spectra similar to their solution spectra.
| Functional Group | Frequency (cm⁻¹) | Notes |
|---|---|---|
| Si–CH₃ | 1275–1245, 865–750 | Strong, sharp band at ~1260 cm⁻¹ is the signature. Some (CH₃)₃Si– compounds show the 1250 cm⁻¹ band split into two components. |
| Si–CH=CH₂ (vinyl) | 1600, 1410, ~1010, ~960 | If aryl groups absent, C-H bands at 3060 and 3020 cm⁻¹ help confirm vinyl on silicon. |
| Si–C₆H₅ (phenyl) | 1600–1590, 1430, 1130–1110, 700–690 | Two phenyl groups on silicon typically split the 1120 cm⁻¹ band into a doublet. |
| Si–O–Si (siloxane) | 1130–1000 | Very strong. Disiloxanes show single band at 1080–1040 cm⁻¹. Long chains show two bands at ~1090 and ~1020 cm⁻¹. |
| Si–H | 2280–2080, 950–800 | Strong band with virtually no interference. Position very sensitive to electronegativity of attached groups. |
| Si–OH (silanol) | 3690 (free), 3400–3200 (H-bonded) | Free Si-OH at 3690 cm⁻¹ is significantly higher than free C-OH. Also shows broad absorption at 950–810 cm⁻¹. |
| Si–OCH₃ | 2840, 1190, 1100–1080 | Sharp 2840 cm⁻¹ band plus strong doublet-like absorption. May be masked by Si-O-Si in mixed samples. |
| Si–OCH₂CH₃ | 1170–1160, 1100 & 1075 | Strong characteristic doublet at 1100 and 1075 cm⁻¹ distinguishes ethoxy from methoxy. |
| Si–Cl | 625–425 | SiCl₂ and SiCl₃ compounds show two or three bands in this range. |
| Si–NH₂ / Si–NH–Si | 3500–3390, 1550–1540, 950–920 | NH₂ appears as a doublet. Tris(trimethylsilyl)amine has strong Si-N-Si band at 915 cm⁻¹. |
| Si–N=C=O | 2280 | Very strong N=C=O band, close to the 2275–2250 cm⁻¹ range for N=C=O on carbon. |
Frequently Asked Questions
Common questions about silane reagents, coupling agents, and silylation techniques.
What is the difference between a silane and a silicone?
Silanes are monomeric organosilicon compounds — small molecules with one silicon atom bonded to organic and/or hydrolyzable groups. Silicones (polysiloxanes) are polymers with repeating Si-O-Si backbones. Silanes serve as building blocks, coupling agents, and blocking agents, while silicones are the finished polymeric materials used as fluids, elastomers, and resins. Learn more about UCT’s silicone polymer products on our Silicone Reagents Guide.
How do I select a silane coupling agent for my application?
Match the organic functional group on the silane to your resin chemistry — amino silanes for epoxies and nylons, methacrylate silanes for polyesters, mercapto silanes for polysulfide sealants, and vinyl silanes for polyethylene. Then choose the number of hydrolyzable groups: three for maximum hydrolytic stability, two for more flexible interfaces (elastomers), or one for the most hydrophobic surfaces. Contact your local UCT sales representative for application-specific recommendations.
Which blocking agent should I use?
For routine derivatization and GC analysis, trimethylsilyl (TMS) reagents like H7300 or B2500 are the standard choice. When you need the blocked derivative to survive subsequent synthetic steps involving mild acid, base, or reducing conditions, use t-butyldimethylsilyl (B2790). For maximum stability, use t-butyldiphenylsilyl (B2805). Triisopropylsilyl (T2885) offers intermediate stability with useful selectivity between primary and secondary alcohols. Many of these are also available through the Selectra-Sil DR product line.
What solvents can I use for silylation reactions?
All solvents for silylation must be aprotic — water will compete with the substrate for the silylating reagent. Common choices are dimethylformamide (DMF), acetonitrile, tetrahydrofuran, hexane, and toluene. When a basic proton acceptor solvent is needed, pyridine and triethylamine are preferred. For TBDMS blocking with B2790, DMF with imidazole as base is the standard protocol.
How do I apply a silane coupling agent to a filler or substrate?
The most common method is deposition from a 2% silane solution in 95% ethanol / 5% water adjusted to pH 4.5–5.5 with acetic acid. Dip or spray the substrate, rinse with ethanol, and cure at 110°C for 5–10 minutes. For powders and fillers, use a 25% solution in alcohol sprayed into a high-intensity mixer. For aminosilanes like A0700 and A0750, omit the acid adjustment. A treatment level of 0.02–1.0% by weight is typical for most fillers.
What is hydrosilylation?
Hydrosilylation is the addition of a Si-H bond across a carbon-carbon multiple bond, and it is one of the most important methods for forming silicon-carbon bonds. The reaction is typically catalyzed by chloroplatinic acid (Speier’s catalyst), which is effective at very low concentrations (10⁻⁵ M) and tolerant of a wide range of organic functionality. The reaction proceeds with anti-Markovnikov selectivity, placing silicon on the terminal carbon. It is the foundation of addition-cure silicone elastomer systems.
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