Abstract: Diastereomers can be separated with good industrial success with the aid of extractive distillation. The separation process is characterized in that an auxiliary which changes the partial pressure of the various diastereomers to be separated to a different degree and thus allows easier separation of the diastereomers by distillation is added during the distillation. Using the present process diastereomic cis/trans-permetric acid methyl esters and mixtures of menthol and isomenthol can be separated with isolation of 99% pure product.

Abstract: With the extraction method, a material exchange column with an ordered packing 2a or 2b on the basis of a plurality of layers 3 stacked parallel to the column axis and making point contact with one another is used. The packing 2a, 2b is perfused by a continuous and a dispersed phase in a counter current. The packing has a very large specific surface area of at least 300 m.sup.2 /m.sup.3 of packing volume. At the periphery of the packing 2a, 2b, the two phase streams are re-circulated into the packing at regular intervals through a rim seal composed of an elastic material not wettable by the dispersed phase. The rim seal is placed round the packing in the form of an elastic tube or pipe and seals the intermediate space between the internal column wall and the packing. A further improvement in the separating capacity can be achieved if pulsating operation is adopted.

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 According to the invention, a first side stream is withdrawn from the extractive distillation column, passed in heat exchange with the bottoms from the extractive distillation column en route to the regeneration column and returned to the extractive distillation column at a point below the point at which it is withdrawn. A second side stream from the extractive distillation column is withdrawn, passed in heat exchange with the bottoms of the regeneration zone and returned to the extractive distillation column.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 thin layer evaporator which has a vapor lock above the solvent inlet is used for the preparation of distillate-free sump product which is obtained as solid from the concentration of solutions of water, organic substances and non-volatile constituents and dissolved in solvents.

Abstract: The combination of valves consists of a double passage cross-over spherical valve with which at least one other single passage spherical valve is connected in series. The passage of the cross-over spherical valve under high pressure is connected to the partition column of a gas chromatograph or liquid chromatograph while the other passage is intended for introducing the sample and is under atmospheric pressure when the sample is injected.

Abstract: The purification of high-melting organic products, such an anthraquinone and substituted anthraquinones, which is substantially free from lower-boiling impurities, by melting the product to be purified by heating, while mechanically conveying the same along a path with a screw conveyer, as for example, in a melting screw; degassing the melt at a reduced pressure in a column, as for example, at a pressure of 50 to 400 mm Hg; passing the degassed melt through a thin film evaporator at a reduced pressure of, for example, 5 to 250 mm Hg to evaporate the high-melting organic product and discharging the remaining high-boiling impurities and such impurities which are not capable of being distilled from the evaporator through a conically tapering sump, while mechanically scraping residue from the sump wall, preferably with the use of a rotating helical screw in the sump; the discharge from the sump being effected into and through an enclosed path at a rate sufficient to prevent liquid accumulating in the sump, while

Abstract: Process for the separation or purification of heat-sensitive compounds by carrier-vapor distillation, wherein the superheated solvent vapor which is loaded with the compound to be distilled is cooled by treatment with condensed solvent in counter-current and the amount of condensed solvent is measured in such a manner that a saturated solution of the compound which is almost at boiling point is formed from the superheated, loaded vapor. The process being especially apted for separating or purifying 4-hydroxybenzaldehydes optionally substituted by one or more C.sub.1 -C.sub.4 -alkoxy groups.