Abstract: Isocyanates are prepared by reacting primary amines with phosgene in a reactor by a process in which a reaction discharge is present in the form of a suspension which contains the isocyanate to be prepared, as a liquid, and carbamyl chlorides as a solid, and the suspension is worked up in a film evaporator, and this process is carried out in a production plant.

Abstract: The invention relates to a process for preparing aromatic diisocyanates by reaction of phosgene with diamines in the gas phase, in which the reaction is carried out in a reaction zone at moderate pressures, i.e. the pressure in this reaction zone is more than 3 bar and less than 20 bar.

Abstract: The present invention relates to a continuous process for preparing isocyanates by reacting primary amines with phosgene, wherein the reaction is carried out in a cascade of at least two tube reactors and the gas phase formed in the reaction is separated off in a phase separator after each reactor and only the liquid phase is passed to the next reactor or to product purification and the reaction volume of the first tube reactor is only a fraction of the total reaction volume.

Abstract: The present invention relates to a process for the continuous preparation of chlorine by reaction of hydrogen chloride with oxygen in the presence of a heterogeneous catalyst, in which the conversion of hydrogen chloride in a single pass through the reactor is restricted to from 15 to 90%.

Abstract: A process for preparing trioxane by trimerization of formaldehyde in aqueous acidic solution and subsequently removing trioxane from a mixture substantially comprising trioxane, water and formaldehyde (crude trioxane product), which comprises a) distilling the crude trioxane product from the trimerization, b) crystallizing the trioxane out and c) removing it from the mother liquor and d) subsequently melting it and e) distilling off further by-products.

Abstract: An arrangement for carrying out chemical reactions comprises at least one distillation column and/or at least one container and at least one circulation evaporator, which are connected to one another via connecting elements, liquid being taken off completely or partly from a tray or from a stacked packing bed or from a dumped packing bed or from a liquid collector of the distillation column or being fed as an external feed stream below the lower tube sheet of the circulation evaporator to said evaporator.

Abstract: A process for preparing methylenedianiline by reacting aniline with formaldehyde in the presence of acid catalysts comprising, in a semicontinuous process, introducing aniline with or without acid catalyst, feeding formaldehyde with or without acid catalyst through a mixing element into a circuit in which aniline with or without acid catalyst and with or without previously added formaldehyde is circulated and, after feeding in at least 50% of the total amount of formaldehyde to be fed in, heating the reaction mixture to a temperature above 75° C. In addition, the invention relates to a process for preparing polyisocyanates by phosgenation of amines obtainable in this manner and to the polyisocyanates obtainable by this process.

Abstract: The invendon relates to a method for the production of a salt-free aqueous hydroxylamine solution by distilling an aqueous solution of an hydroxylammonium salt and a base in a plate column having at least two mechanical plates. The invention is characterized in that packings or structured packings are placed above at least one of the plates of the plate column along the cross section of said column.

Abstract: A process for preparing a salt-free aqueous hydroxylamine solution by reacting an aqueous solution of a hydroxylammonium salt with a base to give a mixture and separating from said mixture by distillation a salt-free aqueous hydroxylamine solution, comprises using as a base an aqueous solution of a mixture of NaOH and KOH in a molar ratio Na+:K+ in the range from 70:30 to 95:5 and with a total concentration of Na+ and K+ in the range from 0.1 to 10 m/m % based on the total amount of the mixture.

Abstract: A process is proposed for the distillation or reactive distillation of a mixture that comprises at least one toxic component, the process being carried out in a column containing a structured packing, having at least one packing layer (1) having a lower end (2) and an upper end (3), the packing layer having an internal geometry varying over its height, in such a manner that in the distillation or reactive distillation, in a first, lower region (6) of the packing layer (1) a bubbling layer having a predominantly disperse gas phase can be established and simultaneously in a second, upper region (7) of the packing layer (1) a film flow having a predominantly continuous gas phase can be established.

Abstract: The invention relates to a method for producing a highly pure, aqueous hydroxylamine solution by distilling an aqueous solution, devoid of salt, of a hydroxyl ammonium salt in a plate column comprising at least two mechanical plates. Said method is characterised in that packing bodies are arranged between at least two plates of the plate column over the cross-section of said column.

Abstract: A process for preparing chlorine by gas-phase oxidation of hydrogen chloride by means of a gas stream comprising molecular oxygen in the presence of a fixed-bed catalyst, which is carried out in a reactor (1) having a bundle of parallel catalyst tubes (2) which are aligned in the longitudinal direction of the reactor and are fixed at their ends into tube plates (3), with a cap (4) at each end of the reactor (1) and with one or more annular deflection plates (6) which are arranged perpendicular to the longitudinal direction of the reactor in the intermediate space (5) between the catalyst tubes (2) and leave circular passages (8) free in the middle of the reactor and one or more disk-shaped deflection plates (7) which leave annular passages (9) free at the edge of the reactor, with an alternating arrangement of annular deflection plates (6) and disk-shaped deflection plates (7) with the catalyst tubes (2) being charged with the fixed-bed catalyst, the hydrogen chloride and the gas stream comprising molecular o

Abstract: A process for preparing chlorine by gas-phase oxidation of hydrogen chloride by means of a gas stream comprising molecular oxygen in the presence of a fixed-bed catalyst, which is carried out in a reactor (1) having a bundle of parallel catalyst tubes (2) which are aligned in the longitudinal direction of the reactor and are fixed at their ends into tube plates (3), with a cap (4) at each end of the reactor (1) and with one or more deflection plates (6) which are arranged perpendicular to the longitudinal direction of the reactor in the intermediate space (5) between the catalyst tubes (2) and leave passages (7) located alternately on opposite sides of the reactor free next to the interior wall of the reactor (1), with the catalyst tubes (2) being charged with the fixed-bed catalyst, the hydrogen chloride and the gas stream comprising molecular oxygen being passed from one end of the reactor via a cap (4) through the catalyst tubes (2) and the gaseous reaction mixture being taken off from the opposite end of

Abstract: Process for preparing chlorine by catalytic gas-phase oxidation of hydrogen chloride over a fixed catalyst bed, which comprises the steps:

Abstract: Process for preparing organic isocyanates, which comprises the steps

Abstract: A process is described for preparing metal formate/formic acid mixtures comprising the following steps:

Abstract: Compounds of the formula (I)

Abstract: A process for preparing methylenedianiline by reacting aniline with formaldehyde in the presence of acid catalysts comprising, in a semicontinuous process, introducing aniline with or without acid catalyst, feeding formaldehyde with or without acid catalyst through a mixing element into a circuit in which aniline with or without acid catalyst and with or without previously added formaldehyde is circulated and, after feeding in at least 50% of the total amount of formaldehyde to be fed in, heating the reaction mixture to a temperature above 75° C.

Abstract: A very pure aqueous solution of free hydroxylamine is prepared by a process in which the dilute, aqueous hydroxylamine solution is concentrated in a column by removing hydroxylamine-containing vapors via a side take-off in the bottom of the column, and very pure hydroxylamine is obtained by condensing the vapors. The novel process can be carried out simply, in a gentle manner and on a large scale and gives electronic grade hydroxylamine.