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Dimethyldichlorosilane is a tetrahedral organosilicon compound with the formula Si(CH 3) 2 Cl 2. At room temperature it is a colorless liquid that readily reacts with water to form both linear and cyclic Si-O chains. Dimethyldichlorosilane is made on an industrial scale as the principal precursor to dimethylsilicone and polysilane compounds.
The methylchlorosilanes react with water to produce hydrogen chloride, giving siloxanes. In the case of trimethylsilyl chloride, the hydrolyzed product is hexamethyldisiloxane: 2 ((CH 3) 3 SiCl + H 2 O → [(CH 3) 3 Si] 2 O + 2 HCl. The analogous reaction of dimethyldichlorosilane gives siloxane polymers or rings: n (CH 3) 2 SiCl 2 + n H 2 O ...
Stock and Somieski completed the hydrolysis of dichlorosilane by putting the solution of H 2 SiCl 2 in benzene in brief contact with a large excess of water. [3] [5] A large-scale hydrolysis was done in a mixed ether/alkane solvent system at 0 °C, which gave a mixture of volatile and nonvolatile [H 2 SiO] n.
The main and most sought-after product is dimethyldichlorosilane: 2 CH 3 Cl + Si → (CH 3) 2 SiCl 2. A variety of other products are obtained, including trimethylsilyl chloride and methyltrichlorosilane. About 1 million tons of organosilicon compounds are prepared annually by this route. The method can also be used for phenyl chlorosilanes. [17]
Dimethyldichlorosilane (Si(CH 3) 2 Cl 2) is a key precursor to cyclic (D 3, D 4, etc.) and linear siloxanes. [5] The main route to siloxane functional group is by hydrolysis of silicon chlorides: 2 R 3 Si−Cl + H 2 O → R 3 Si−O−SiR 3 + 2 HCl. The reaction proceeds via the initial formation of silanols (R 3 Si−OH): R 3 Si−Cl + H 2 O ...
The following compounds are liquid at room temperature and are completely miscible with water; they are often used as solvents. Many of them are hygroscopic.
The chemical formula of PDMS is CH 3 [Si(CH 3) 2 O] n Si(CH 3) 3, where n is the number of repeating monomer [Si(CH 3) 2 O] units. [4] Industrial synthesis can begin from dimethyldichlorosilane and water by the following net reaction:
Methyltrichlorosilane vapor reacts with water on surfaces to give a thin layer of methylpolysiloxane, which changes the contact angle of the surface to water. This effect arises because of the oriented layer of methyl groups, making a water-repellent film. [ 4 ]