PROCESS FOR PREPARING CYCLIC DIMETHYLPOLYSILOXANES

摘要

Cyclic dimethylpolysiloxanes are prepared by heating a mixture containing linear or branched organopolysiloxanes consisting of at least 50 mol percent dimethylsiloxane units and aqueous sulfuric acid in which the aqueous sulfuric acid contains from 50 to 85 percent by weight of sulfuric acid in the absence of an organic solvent while simultaneously recovering the cyclic dimethylpolysiloxanes thus formed. This process can be carried out at lower temperature than heretofore possible, and it does not require anhydrous conditions, nor does it necessitate the separation of the catalyst. The process produces higher yields of cyclic dimethylpolysiloxanes than was obtained heretofore in the same size equipment and in a shorter period of time.