write short notes on: -> synthesis of silicones -> silicon dioxide or silica -> geolites

Asked by GARIMA SRIVASTAVA | 4th Mar, 2011, 02:39: AM

Expert Answer:

Dear Student

 

1. Silicones :-- 

Silicones are interesting and commercially important class of polymers can be synthesised by the hydrolysis of suitably functionalized silicon derivatives. Note that leaving groups (halides, alkoxides, carboxylates, or amines) attached to silicon react readily with water, and hydrolyze to silanols. These silicon-analogs of alcohols are also unstable, and in most cases quickly dimerize to produce siloxanes. Difunctional variations lead to linear polymers, as shown below for the polymerization of dimethyl dimethoxy silane.

 

Silica:The chemical compound silicon dioxide is also known as silica. It is an oxide of silicon with the chemical formula SiO2. It has been known for its hardness. Silica is used primarily in the production of glass for windows, drinking glasses, beverage bottles, and many other uses. The majority ofoptical fibers for telecommunications are also made from silica. It is a primary raw material for many whiteware ceramics such asearthenware, stoneware, porcelain, as well as industrial Portland cement.

Zeolites: Zeolites are microporous crystalline solids with well-defined structures. They contain silicon, aluminium and oxygen in their framework and cations, water and/or other molecules wthin their pores.

Many of them occur naturally as minerals, and are extensively mined in many parts of the world. Others are synthetic, and are made commercially for specific uses, or produced by research scientists trying to understand more about their chemistry.

We hope that clarifies your query.

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Answered by  | 4th Mar, 2011, 12:54: PM

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