Abstract: This present invention relates to a process for thermally cracking carbamic acid esters into the corresponding isocyanate and hydroxyl compounds in the liquid phase, wherein the reaction proceeds as a reactive rectification in the stripping zone of a column and in an inert, high-boiling solvent, which acts as a buffer to keep the reaction away from the evaporator region of the column.

Abstract: The invention relates to a method for the purification by distillation of p,p-bisphenol A from the melt.The p,p-bisphenol A melt thus obtained is highly heat-stable, stable in storage and colour-stable, is free from high-boiling components and no longer contains any surface-active or non-distillable metal, salt, acid or polymer components and no sulphur-containing components; o,p-BPA and phenol are removed and the low-boiling components are scarcely detectable.

Abstract: The preparation of dimethyl carbonate by reaction of methanol, carbon monoxide and oxygen in the presence of Cu compounds is carried out in distillation units and the water of reaction is removed at least partially from the stripping region or the bottom phase.

Abstract: A method of controlling a heat exchanger wherein the enthalpy flow into the heat exchanger serves as a correcting variable. The robust and versatile control method is particularly suitable for use in endothermic reactions and for distillation.

Abstract: In a distillation column with vaporous sidestream removal, the vaporous product removed is condensed in a condenser. The vapor pipe provided for the removal of product opens into a dip tank of which the upper end is connected to the condenser while its lower end is connected to a discharge pump. Inert gas present in the condensate is returned to the column above the sidestream removal through an inert gas pipe arranged at the upper end of the condenser.

Abstract: A process and apparatus for the separation of components from a mixture which forms an azeotrope is disclosed by subjecting the mixture to extractive distillation to remove one of the components and regeneration to separate another component from the extracting agent added to the extractive distillation column. According to the invention, a first side stream is withdrawn from the extractive distillation column, passed in heat exchange with the bottoms from the extractive distillation column en route to the regeneration column and returned to the extractive distillation column at a point below the point at which it is withdrawn. A second side stream from the extractive distillation column is withdrawn, passed in heat exchange with the bottoms of the regeneration zone and returned to the extractive distillation column. For this purpose, separate heat exchangers are used for the respective side streams.

Abstract: A process for preparing monochloropinacoline (1-chloro-3,3-dimethyl-butan-2-one) by contacting a stoichiometric excess of pinacoline with chlorine at a temperature of -20.degree. to +70.degree. C.