Abstract: Crude chlorosilane streams containing lower-boiling chlorosilanes and higher-boiling chlorosilanes are separated by contacting them with a distillation aid. The lower-boiling chlorosilanes are separated from the crude chlorosilane stream, and then the distillation aid and the higher-boiling chlorosilanes are separated from one another. The distillation aid is a mono-cyano-substituted organic compound, a nitro-substituted organic compound, a mono-cyano-substituted organosilicon compound, a nitro-substituted organosilicon compound, or a mixture thereof. These distillation aids increase the relative volatility of crude chlorosilane streams such as methyltrichlorosilane and dimethyldichlorosilane resulting in improved separation at lower capital and/or fixed costs.

Abstract: Linear hydroxy endblocked linear polyorganosiloxanes, linear chloro-endblocked polyorganosiloxanes, and mixtures thereof, are redistributed in a process by contacting the linear polyorganosiloxanes, with a diorganodichlorosilane having the formula R?2SiCl2, wherein R? is an alkyl group containing 1-8 carbon atoms; in the presence of an aqueous hydrochloric acid catalyst; to form a redistributed mixture containing cyclic polyorganosiloxanes and chloro-endblocked polyorganosiloxanes. The process generates less amounts of undesired branched siloxane species than processes which utilize an alumina catalyst.

Abstract: Chemical grade silicon metalloid having improved performance in the direct process for making organohalosilanes is selected by (A) measuring the temperature of each batch of silicon metalloid during both the refining and the casting of the silicon metalloid; (B) measuring the elemental impurity levels in each batch of the silicon metalloid after refining of the silicon metalloid; (C) predicting the properties of the slag phase produced during refining of the silicon metalloid based on equilibrium calculations using the elemental impurity levels and the measured temperatures of each batch of silicon metalloid; and (D) selecting a chemical grade silicon metalloid for use in the direct process for making organohalosilanes based upon the predicted slag properties; such that the slag density, the viscosity, and the melting point of the slag, are within acceptable and predetermined ranges for each individual batch.

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: Polysiloxane hydrolyzates are neutralized by treating polysiloxane hydrolyzates containing residual acidic constituents with carbon, and then the carbon is removed from the treated neutralized polysiloxane hydrolyzate. Some examples of polysiloxane hydrolyzates that can be treated are hydride functional polysiloxane hydrolyzates and polydiethylsiloxane hydrolyzates. The carbon neutralizing agent especially preferred is carbon derived from bituminous coal. The carbon is removed from the treated neutralized polysiloxane hydrolyzate by passing it through solid liquid separation devices such as plate and frame filter presses, polishing filters, and post filters for removing fines.

Abstract: A process for preparing cyclic organohydrogensiloxanes is disclosed. The process comprises the steps of (A) and (B). Step (A) comprising contacting a silane of the formula RHSiCl2, where R is selected from alkyl radicals having 1 to 12 carbon atoms and aryl radicals, with water to form a hydrolyzate. The hydrolyzate formed in step (A) comprising cyclic organohydrogensiloxanes and linear organohydrogensiloxanes. Step (B) comprising contacting the hydrolyzate formed in (A) with an acidic rearrangement catalyst in the presence of an inert liquid diluent to increase the ratio of the cyclic organohydrogensiloxanes to linear organohydrogensiloxanes in the hydrolyzate. The process further characterized by that the acidic rearrangement catalyst is an organic compound containing a strong acid group which is dissolved in the inert diluent present.