Abstract: Aromatic diamines and polyamines are produced by a continuous process for the catalytic hydrogenation of the corresponding dinitro and polynitro compounds at elevated temperature. Heat removed from the reaction mixture may be used to produce steam with an overpressure of .gtoreq.2 bar.

Abstract: A process for recovering a distillate of tolylene diisocyanate and an isocyanate-group-containing sump product containing less than 200 ppm (by weight) tolylene diisocyanate from A) distillation residues obtained in the production of tolylene diisocyanate by mixing of the distillation residues A) with B) optionally urethane- and/or allophanate-modified polyisocyanates or polyisocyanate mixtures of the diphenyl methane series, heating of the mixture to 190.degree. to 250.degree. C. and simultaneously or subsequently working up by distillation.

Abstract: The present invention is directed to a mixer for mixing at least two free-flowing, reactive or unreactive substances comprising(a) a casing having at least two inlets and at least one outlet,(b) a rotatable shaft extending through the casing,(c) at least one rotor disc attached to the shaft such that the rotor disc is perpendicular to the shaft,(d) at least one stator disc attached to the casing such that the stator disc is parallel to the rotor disc and has an opening such that shaft can pass through the stator disc,(e) optionally at least one running wheel attached to the shaft and containing openings such that when the shaft is rotating, the running wheel provides a pumping effect to the mixture passing through the mixer,(f) at least one inlet through the casing for introducing a first substance axially to the shaft and against the rotor disc and(g) at least one inlet for introducing a second substance against a rotor disc at a point which is radially outward from the introduction of the first substance.

Abstract: The present invention is directed to a process for the production of a mono- and/or polyisocyanate by the phosgenation of a mono- and/or polyamine in a mixer which comprises(a) a casing having at least two inlets and at least one outlet,(b) a rotatable shaft extending through the casing,(c) at least one rotor disc attached to the shaft such that the rotor disc is perpendicular to the shaft,(d) at least one stator disc attached to the casing such that the stator disc is parallel to the rotor disc and has an opening such that the shaft can pass through the stator disc,(e) optionally at least one running wheel attached to the shaft and containing openings such that when the shaft is rotating the running wheel provides a pumping effect to the reaction mixture passing through the mixer,(f) at least one inlet through the casing for introducing a phosgene solution axially to the shaft and against the rotor disc,(g) at least one inlet through the casing for introducing a mono- and/or polyamine amine solution or suspe

Abstract: An amine is separated from an aqueous solution of amine and volatile organic compounds by distillation in a column. The vapors generated during distillation are condensed. The condensed vapors are then passed into a separating device in which the volatile organic compounds are removed. The liquid remaining in the separating device is then fed to the head of the distillation column. Water is removed from the column in a sidestream and diamine is the residue. This process is particularly effective in recovering aromatic diamines from solutions which accumulate during hydrogenation of dinitro aromatic compounds.