S5505

Silica, fumed

powder, 0.2-0.3 μm avg. part. size (aggregate)

• Synonym(s): Silica, Silicic anhydride, Silicon dioxide, Silicon dioxide amorphous
• Linear Formula: SiO₂
• CAS Number: 112945-52-5
• Molecular Weight: 60.08
• MDL number: MFCD00011232
• UNSPSC Code: 12352103
• PubChem Substance ID: 24899656
• NACRES: NA.22

Properties

• form: powder
• surface area: 200 m²/g (±25 m²/g)
• refractive index: n20/D 1.46 (lit.)
• avg. part. size: 0.2-0.3 μm (aggregate)
• density: 2.3 lb/cu.ft at 25 °C (bulk density)(lit.)
• SMILES string: O=[Si]=O
• InChI: 1S/O2Si/c1-3-2
• InChI key: VYPSYNLAJGMNEJ-UHFFFAOYSA-N

Description

Application

Fumed Silica (SiO₂) has been used as a precursor to synthesize:

• Chlorosilanes via silanization, which are used to prepare silica/polydimethylsiloxane membranes to study permeation performance.
• Silicon carbide (SiC) nanoparticles by sol-gel method.
• Calcium silicate hydrate (C-S-H) by treating with CaO and water via hydrothermal reaction.
• Si/PtO₂ catalyst for the selective conversion of cinnamaldehyde to cinnamic acid by aerobic oxidation.

It can be also used in the preparation of:

• Silica sulfuric acid catalyst used in the synthesis of 3,4-dihydropyrimidin-2(1H)-ones via one-pot three-component Biginelli reaction.
• HClO₄-SiO₂ heterogeneous catalyst used in the synthesis of tetrasubstituted imidazoles.

Features and Benefits

Has interesting thickening and thixotropic properties, and an enormous external surface area.

Other Notes

Particle sizes are for primary particles, which form branched, chain-like aggregates a few tenths of a micron long.

Safety Information

• Storage Class: 11 - Combustible Solids
• wgk_germany: WGK 2
• flash_point_f: Not applicable
• flash_point_c: Not applicable
• ppe: Eyeshields, Gloves, type N95 (US)