Process for preparing organopolysiloxanes

A process for the production of an organopolysiloxane of a targeted molecular weight, comprising:

• a) in a first step, reacting one or more chlorosilanes with from 0.002 to 0.6 mol of water per mole of hydrolyzable chlorine and 0.3 to 1.6 mol alcohol per mole of hydrolyzable chlorine at a temperature and a pressure at least one of which is not the ambient temperature or pressure to produce a partial hydrolysate, and regulating the molecular weight of an organopolysiloxane product later isolated by adjusting at least one of the temperature and pressure, an increased pressure elevating said molecular weight and an increased temperature lowering said molecular weight;
• b) in a second step, optionally mixing the partial hydrolysate with a water-insoluble organic solvent having a density of less than 0.9 g/ml, and metering in water in an amount of from 0.2 to 100 mol per mole of hydrolyzable chlorine in the chlorosilane(s);
• and
• c) in a third step, separating an aqueous alcoholic phase from an organopolysiloxane of said targeted molecular weight.