Dimethylsilicon Dichloride

Submitted BY Euoene G. Rochow Checked by William S- TATixiCKf 

The products may be analyzed by hydrolyzing in a mixture of ice and ether and titrating liberated hydrochloric acid with standard base. 

Dimethyldichlorosilane is a colorless liquid that freezes at —76.1°, boils at 70.0°, and has a density of 1.06 g./ml. at 25°. It hydrolyzes readily in moist air and reacts with water to form a mixture of polymeric dimethylsiloxanes ( methyl silicone ) containing products possessing both cyclic and linear structures.  

CjHBSiCl, + SO2CI2 ClCjH SiCl, + SO2 + HCl ClC2H4SiCl3 -f- CsHtN CH2=CHSiCl, + C.H7N HCI 

Vinyl silicon compounds have been prepared by the direct reaction of vinyl chloride with elemental silicon and by 

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To titrate alkylchlorosilanes such as trimethylsilicon chloride, dimethylsilicon dichloride, methylsilicon trichloride and silicon tetrachloride, titration in methyl cyanide with 0.05 n phenazone or nitron in methyl cyanide, or with a solution of amidopyrine in benzene by visual and potentiometric methods is suggested173. The indicators used are crystal violet, dimethylaminoazobenzene, bromocresol purple, methyl orange, bromo-phenol blue and gallo sea blue (C.I.-Mordant Blue 14) the addition of benzene, toluene, chlorobenzene or carbon tetrachloride does not effect the results. 

Dimethylsilicondihydroxide, (CH3)2Si(OH)2, can be obtained by the rapid hydrolysis in water, or even in moisture from the air, of dimethylsilicon-dichloride, (CH3)2SiCl2. 

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