Abstract: Sulfuric acid contaminated with byproducts of chloromethane scrubbing is regenerated for reuse in the scrubbing process by diluting with water to not lower than about a 55 weight percent concentration, heating the diluted acid to boiling at not more than about 135° C., concentrating the acid to a concentration of minimally 80 weight percent at a temperature of at least 170° C., and reacting the concentrated acid with an oxidizing agent.

Abstract: The invention relates to a process for the preparation of chloromethane from methanol and hydrogen chloride contaminated with Si compounds, the Si compounds being methylchlorosilanes, methoxymethylsilanes and hydrolysis and condensation products thereof, in which some of the Si compounds are removed by condensation from the chloromethane formed and remaining Si compounds are washed out with methanol, the methanol thus obtained and containing Si compounds being used for the further preparation of chloromethane with hydrogen chloride.

Abstract: Sulfuric acid contaminated with byproducts of chloromethane scrubbing is regenerated for reuse in the scrubbing process by diluting with water to not lower than about a 55 weight percent concentration, heating the diluted acid to boiling at not more than about 135° C., concentrating the acid to a concentration of minimally 80 weight percent at a temperature of at least 170° C., and reacting the concentrated acid with an oxidizing agent.

Abstract: The invention relates to a process for the preparation of chloromethane from methanol and hydrogen chloride contaminated with Si compounds, the Si compounds being methylchlorosilanes, methoxymethylsilanes and hydrolysis and condensation products thereof, in which some of the Si compounds are removed by condensation from the chloromethane formed and remaining Si compounds are washed out with methanol, the methanol thus obtained and containing Si compounds being used for the further preparation of chloromethane with hydrogen chloride.

Abstract: In the process, used sulfuric acid which contains, as minor constituents, methylsulfuric acid, dimethyl ether, methanol, aliphatic and olefinic hydrocarbons, chlorinated hydrocarbons and oligomeric siloxanes, in a first step;(1) used sulfuric acid is diluted by introducing steam and optionally by adding liquid water to a concentration of at most 55% by weight sulfuric acid and is heated to boiling at a maximum of 135.degree. C. and in a second step;(2) the sulfuric acid from the first step is reacted with an oxidizing agent at a temperature of from 20.degree. C. to 130.degree. C.

Abstract: The present invention describes a process wherein dimethyldichlorosilane is reacted, in a first step, with water present in hydrochloric acid to give a crude hydrolysate comprising cyclic and linear, chlorine-containing polydimethylsiloxanes and gaseous hydrogen chloride and, in a second step, the crude hydrolysate is treated with steam to reduce the chlorine content and form hydrochloric acid, with the hydrochloric acid formed in the second step being used in the first step.