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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.
2 CH 3 Cl + Si → (CH 3) 4−n SiCl n + other products. While this reaction is the standard in industrial silicone production and is nearly identical to the first direct synthesis of methyltrichlorosilane, the overall process is inefficient with respect to methyltrichlorosilane. [2]
Tetramethylsilane is the accepted internal standard for calibrating chemical shift for 1 H, 13 C and 29 Si NMR spectroscopy in organic solvents (where TMS is soluble). In water, where it is not soluble, sodium salts of DSS, 2,2-dimethyl-2-silapentane-5-sulfonate, are used instead.
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 relevant reactions are (Me = CH 3): x MeCl + Si → Me 3 SiCl, Me 2 SiCl 2, MeSiCl 3, Me 4 Si 2 Cl 2, ... Dimethyldichlorosilane (Me 2 SiCl 2) is of particular value as a precursor to silicones, but trimethylsilyl chloride (Me 3 SiCl) and methyltrichlorosilane (MeSiCl 3) are also valuable.
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: n Si(CH 3) 2 Cl 2 + (n+1) H 2 O → HO[Si(CH 3) 2 O] n H + 2n HCl. The polymerization reaction evolves ...
TMS is a contaminant in the atmospheres of spacecraft, where it arises from the degradation of silicone-based materials. [5] Specifically, it is the volatile product from the hydrolysis of polydimethylsiloxane, which are generally terminated with trimethylsilyl groups: (CH 3) 3 SiO[Si(CH 3) 2 O] n R + H 2 O → (CH 3) 3 SiOH + HO[Si(CH 3) 2 O] n R
rn(si(ch 3) 3) 2 + h 2 o → o(si(ch 3) 3) 2 + rnh 2 where X is a halogen and R is an alkyl . This method has been extended to aminomethylation via the reagent CH 3 OCH 2 N(Si(CH 3 ) 3 ) 2 , which contains a displaceable methoxy group CH 3 O –.