Dimethyldiethoxy silane

Solvents which swell these siloxanes are usually hydrocarbons-such as toluene. Soln is obtd in ethyl acetate and CC14 (Ref 4). Prepn of the cy do dimethyl siloxanes is accomplished by the complete hydrolysis of dimethyldiethoxy-silane. The silane is heated with a mixt, in equal volumes, of 95% ethanol and coned HC1 (1 1) at bp for 4—8 hrs. The reaction product is washed, dried under reduced pressure at 120°, and the volatile dimethyl siloxanes are then distd off up to 250° (at 4mm). The mixt which has been distd off is again treated with 20% HQ at bp,... 

Cohydrolysis of 1,2-diethoxytetramethyldisilane with dimethyldiethoxy-silane yields as the major product a seven-membered cyclic compound (XI) in which two dimethylsiloxy units are incorporated, but no traces of a five-membered product (XII) (109). 

Silanes used for treatment dimethyldiethoxy silane, 3-(methacryloxy) propyltrimethoxy silane, vinyl triethoxy silane, amino silane. Silane coating was estimated to be 0.2 wt%. Treatment with epoxy silane has been used followed by PS-maleic anhydride grafting through amine spacer. 

The interaction between dimethyldiethoxy silane and trimethylethoxy silane with water, in the presence of 1 NaOH per 100 silicon atoms, gives rise to the formation of simethicone with the elimination of a calculated amount of ethanol. The presence of NaOH, as a catalyst, ensures the formation of only straight chain polymers. 

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