[Mg].II.ClC(C)C.[CH3:8][O:9][Si](OC)(OC)OC.CO.C([Si:22]([CH:28]([CH3:30])[CH3:29])([CH:25]([CH3:27])[CH3:26])[O:23][CH3:24])(C)C>COC(C)(C)C>[CH:25]([Si:22]([CH:28]([CH3:30])[CH3:29])([O:9][CH3:8])[O:23][CH3:24])([CH3:27])[CH3:26]Under an inert gas, 24.2 g magnesium chips (1.0 mol) were combined with about 20 ml methyl-tert-butylether, an iodine crystal and 3.1 g 2-chloropropane (0.04 mol). To start the reaction a solution of 61.9 g tetramethoxysilane (0.41 mol) and 75.4 g 2-chloropropane (0.96 mol) in 140 ml methyl-tert-butylether was added dropwise, with stirring, to the first mixture at a rate to maintain a moderate reflux. After addition of the solution, the reaction was allowed to reflux for six more hours. After cooling the reaction mixture, 6.0 g methanol (0.19 mol) was added, the mixture was stirred for a few minutes and then the resulting precipitate was removed by filtration. After washing the filter cake with several portions of methyl-tert-butylether, the solvent was distilled from the combined filtrates. The remaining residue consisted of 70.5 g diisopropyldimethoxysilane (98% of the theoretical yield) which had a purity of 98% according to GC. Triisopropylmethoxysilane was not detected by GC.
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