A review on synthesis of tetraethoxy silane, used in surfase coatings

Organic silicates can be considered formally as esters of orthosilicic acid Si(OH)4. Thus Si(OEt)4 can be called tetraethyl orthosilicate (TEOS). Alternatively, Si(OEt)4 can be regarded as a derivative of silane SiH4 and called tetraethoxysilane. Alkoxy silanes, particularly tetraethoxy silane, are widely used as adhesion promoters, crosslinkers and hydrophobic compounds and have now great scientific and technological interest due to their novel properties. Previously, manufacturing of tetraethoxy silane from reaction between silicon tetrachloride and ethanol was prevalent. Difficulties with control of pollution and plant corrosion make some alternative method, such as direct reaction between silicon and ethanol. Ultimately the ethyl orthosilicate can undergo hydrolysis and condensation polymerisation to give ethyl polysilicates. The intent of this paper is to briefly review different approaches to synthesize tetraethoxy silane in recent five decades contains their process in terms of reaction efficiency, ease of process, raw materials accessibility, existence of by-products and environmentally aspects.