Silica Precipitated from Organic Liquids

Silica of low bulk density, 0.016 g cm , and area of 300 ni g useful as a rubber filler is made by precipitating silica from alcohol, generated from ethyl silicate (444). Thus 6.8 ml of (CjHgO) Si and 20 ml of concentrated NH4OH are reacted in 280 ml of alcohol. The process is closely related to one developed by Stbber (445) for making sols. 

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Instead of drying silica gels from water, other liquids of lower surface tension are sometimes employed. Behrman (297) dehydrated silica ge4 from ammonia. Teter (298) washed a silica-alumina gel with methanol and dried it in an autoclave. Kearby (299) produced a pulverulent low density, finely divided gel by treating precipitated gel with water-miscible organic liquids such as alcohols or ketones and... 

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