Structure of Silica Gel
- Inorganic macropolymer made of [SiO4]4- tetrahedra
- Polar Si-OH (silanols) groups on the surface
Functionalized Silica Gels
- Functional moieties grafted on the silanol groups (-OH) of silica
- End-capping of residual (-OH) to remove binding capacity
- No non-specific binding
- High yields
Advantage over Polymer:
- Consistent Loading Lot-to-Lot
- Rigid Porous Structure; No swelling, Solvent Independent and Fast kinetics
-Easily Scalable. works on the microgram to the multi-ton scale
- Easier to Handle; Free flowing, No static Charge. It does not require extensive washing for high recoveries and will not stick to glasware. Easy to Automate.
- Higher Density; Small volume of Silica required
SiliaBond® alphabetical listing:
Thermal Stability (Comparing Silica to Polystyrene (PS) resin)
Most functional Silica's can withstand temperatures of over 200°C and are suitable for use in microwave synthesizers.
1. SiliaBond C1 stirred for 4h at 110°C in Toluene
2. PS resin stirred for 1h at 110°C in Toluene
Mechanical Stability; Works well with overhead stirring and can be used with a bottom coupled spin bar for up to four hours.
Limits of Use
Si-O-Si bond susceptible to hydrolysis under certain conditions:
- Aqueous solution at high or very low pH
- Keep the pH between 2 and 12 when using water