Abstract: Chlorosilanes such as dimethyldichlorosilane are hydrolyzed in a first super-azeotropic hydrochloric acid distillation column A to produce cyclosiloxanes, chlorosiloxanes, and hydrogen chloride gas. The cyclosiloxanes and the chlorosiloxanes are washed and separated according to their volatility in a second sub-azeotropic hydrochloric acid distillation column B, to produce a substantially chloride free volatile cyclosiloxane stream and a substantially chloride free non-volatile siloxane stream. The process is substantially chloride efficient.

Abstract: Chlorosilanes such as dimethyldichlorosilane are hydrolyzed in a first super-azeotropic hydrochloric acid distillation column A to produce cyclosiloxanes, chlorosiloxanes, and hydrogen chloride gas. The cyclosiloxanes and the chlorosiloxanes are washed and separated according to their volatility in a second sub-azeotropic hydrochloric acid distillation column B, to produce a substantially chloride free volatile cyclosiloxane stream and a substantially chloride free non-volatile siloxane stream. The process is substantially chloride efficient.

Abstract: Chlorosilanes are hydrolyzed to a hydrolysate in a looped system containing a hydrolysis reactor, an HCl purifier, a wash means, and a separator. The steps of the method comprise: (i) feeding chlorosilanes from an external source to the hydrolysis reactor, (ii) feeding water from an external source to the wash means, (iii) feeding a high concentration aqueous HCl of at least 10 percent by weight HCl from an external source to the hydrolysis reactor between the wash means and the hydrolysis reactor, (iv) removing anhydrous hydrogen chloride from the HCl purifier, (v) removing hydrolysate from the wash means, and (vi) removing a low concentration aqueous hydrogen chloride of 0.1 to less than 10 percent by weight HCl from the looped system.