Method for producing organopolysiloxanes

A process for the preparation of organopolysiloxanes, comprising partially hydrolyzing and then further hydrolyzing chlorosilanes by sequential first and second steps consisting of:

• in a first step, partially hydrolyzing chlorosilanes by reacting chlorosilanes and optionally an alkoxysilane in a loop reactor with a liquid component consisting essentially of water and alcohol, containing from 0.002 to 0.6 mol of water per mole of hydrolyzable chlorine and from 0.3 to 1.6 mol of alcohol per mol of hydrolyzable chlorine to form an Si component which is a partial hydrolysate, the molar ratio of water to alcohol being from 0.001 to 1.5, wherein gaseous HCl is generated and withdrawn as a gas from the loop reactor during the first step,
• in the second step, further hydrolyzing the partial hydrolysate of the first step by metering in a chlorosilane hydrolysis component consisting essentially of water and optionally alcohol, in an amount of from 0.2 to 100 mol of water per mol of Si component wherein the reaction mixture obtained in the first step is optionally mixed with a water-insoluble organic solvent having a density of less than 0.9 kg/l, wherein one or more chlorosilanes and/or one or more alkoxysilanes are optionally added in the second step, wherein in the second step, the water of the second hydrolysis component hydrolyzes and condenses the Si component to an organopolysiloxane product, and
• in a third step, forming a two phase mixture comprising an aqueous alcoholic liquid phase and an organopolysiloxane phase containing the organopolysiloxane product, and separating the aqueous alcoholic liquid phase from the organopolysiloxane phase containing the organopolysiloxane product in a liquid/liquid separation, wherein in the second step, at least one of chlorosilane(s), alcohol(s), or alkoxysilane(s) are added.

A process for the preparation of organopolysiloxanes, comprising partially hydrolyzing and then further hydrolyzing chlorosilanes by sequential first and second steps consisting of:

• in a first step, partially hydrolyzing chlorosilanes by reacting chlorosilanes and optionally an alkoxysilane in a reactor with a liquid component consisting essentially of water and alcohol, containing from 0.002 to 0.6 mol of water per mole of hydrolyzable chlorine and from 0.3 to 1.6 mol of alcohol per mol of hydrolyzable chlorine to form an Si component which is a partial hydrolysate, the molar ratio of water to alcohol being from 0.001 to 1.5, wherein gaseous HCl is generated and withdrawn as a gas from the loop reactor during the first step,
• in a second step, further hydrolyzing the partial hydrolysate of the first step by metering in a chlorosilane hydrolysis component consisting essentially of water and optionally alcohol, in an amount of from 0.2 to 100 mol of water per mol of Si component wherein the reaction mixture obtained in the first step is optionally mixed with a water-insoluble organic solvent having a density of less than 0.9 kg/l, wherein one or more chlorosilanes and/or one or more alkoxysilanes are optionally added in the second step, wherein in the second step, the water of the chlorosilane hydrolysis component hydrolyzes and condenses the Si component to an organopolysiloxane product, and
• in a third step, forming a two phase mixture comprising an aqueous alcoholic liquid phase and an organopolysiloxane phase containing the organopolysiloxane product, and separating the aqueous alcoholic liquid phase from the organopolysiloxane phase containing the organopolysiloxane product in a liquid/liquid separation, wherein the aqueous alcoholic liquid phase in the third step is an acidic aqueous alcoholic liquid phase containing dissolved HCl, the acidic aqueous alcoholic phase alkaline to form an alkaline aqueous alcoholic phase, and recovering alcohol from the alkaline aqueous alcoholic phase by distillation, and introducing the alcohol thus recovered into the first step as a source of alcohol in the first step.