Preparation of branched methyloligodiphenylsiloxanes

Methyloligodiphenylsiloxanes are synthesised in two stages. The first stage consists of the catalytic condensation of dihydroxydiphenylsilane in the presence of a catalyst, an aqueous ammonia solution at 100-120 °C  

The second stage consists of the heterofunctional condensation of a, -dihydroxydiphenylsiloxane obtained at the first stage with triacetoxy-methylsilane  

Raw stock dihydroxydiphenylsilane (14.5-16.5% of hydroxyl groups, pH of the aqueous extract is 6-7) triacetoxymethylsilane (toluene solution, the semi-product of polyphenylsilsesquioxane, which is obtained in the acetylation of phenyltrichlorosilane aqueous ammonia (reagent grade, at least 25% of ammonia, not more than 0.002% of carbonates, not more than 0.0001% of chlorides), B brand of coal toluene (at least 95% (vol.) of the 

The production of silicon tetrachloride (Fig. 46) comprises the following main stages the condensation of dihydroxydiphenylsilane and water distillation the heterofunctional condensation of the product of stage I with tri-acetoxymethylsilane the flushing of the obtained product with water and the distillation of the solvent. 

The speed of the distillation of the azeotropic mixture (water + toluene) is regulated by supplying water into the jacket of reactor 1. The distilled water is collected in the lower part of Florentine flask 4, and the separated toluene is sent back into the reactor. To calculate the number of hydroxyl groups, the water poured out of the Florentine flask is measured and sent to biochemical purification. 

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