Abstract:
The invention relates to a process for preparing polyisocyanates by reacting organic amines with phosgene, wherein the reaction is carried out in at least three stages, with the first stage being carried out in a mixing apparatus, the second stage in at least one residence apparatus and the third stage in at least one separation apparatus and the pressure in each successive stage being lower than that in the previous stage.
Abstract:
The invention relates to a process for preparing polyisocyanates by reacting organic amines with phosgene, wherein the reaction is carried out in at least three stages, with the first stage being carried out in a mixing apparatus, the second stage in at least one residence apparatus and the third stage in at least one separation apparatus and the pressure in each successive stage being lower than that in the previous stage.
Abstract:
A process is provided for preparing light-colored isocyanates which can be used for preparing urethane compounds, in particular polyurethanes, for example polyurethane foams.
Abstract:
The invention provides a process for preparing diphenylmethanediamine, comprising the steps of: a) reacting aniline with formaldehyde in the presence of an acid, b) neutralizing the predominant part of the acid with ammonia and/or aqueous ammonia solution, c) separating the reaction mixture from step b) into an aqueous phase and an organic phase, d) neutralizing the other part of the acid, present in the organic phase, with aqueous alkali metal hydroxide solution, e) separating the reaction mixture from step d) into an aqueous phase and an organic phase, f) treating the aqueous phase obtained in step c) or optionally the combined aqueous phases from steps c) and e) with at least one oxide or hydroxide of an alkaline earth metal, g) removing the ammonia obtained in step f).
Abstract:
The invention relates to a process for preparing isocyanates by reaction of amines with phosgene in the presence of inert organic solvents in a reactor and subsequent work-up of the reaction mixture leaving the reactor, wherein the solvent is separated off in a two-stage or multistage, preferably two-stage, distillation process in which the solvent is separated off at a pressure of 0.1-15 bar in a first apparatus and at 1-900 mbar in a second apparatus or further apparatuses, with the heat of condensation of the solvent vapor from the first apparatus being used for partial or complete vaporization of solvent in the second apparatus.
Abstract:
The present invention provides a liquid methylene bis(phenylisocyanate) composition including a high concentration of methylene bis(phenylisocyanate) which has an improved storage stability. The invention further provides a method of making the liquid methylene bis(phenylisocyanate) compositions of the present invention.
Abstract:
The present invention provides a liquid methylene bis(phenylisocyanate) composition including a high concentration of methylene bis(phenylisocyanate) which has an improved storage stability. The invention further provides a method of making the liquid methylene bis(phenylisocyanate) compositions of the present invention.
Abstract:
A reactor (1) for preparing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a solid catalyst, which reactor has a bundle of parallel catalyst tubes (2) aligned in the longitudinal direction of the reactor whose ends are fixed in tube plates (3) and have a cap (4) at each end of the reactor (1), and has deflection plates (6) which are aligned perpendicular to the longitudinal direction of the reactor in the intermediate space (5) between the catalyst tubes (2) and leave free passages (7) located alternately opposite one another on the interior wall of the reactor, and in which the catalyst tubes (2) are charged with the solid catalyst, the gaseous reaction mixture is passed from one end of the reactor via one cap (4) through the catalyst tubes (2) and is taken off from the opposite end of the reactor (1) via the second cap (4) and a liquid heat transfer medium is passed through the intermediate space (5) around the catalyst tubes (2), where the reactor (1) has no tubes in the region of the passages (7), is proposed.
Abstract:
The invention provides a process for preparing diphenylmethanediamine, comprising the steps of: a) reacting aniline with formaldehyde in the presence of an acid, b) neutralizing the predominant part of the acid with ammonia and/or aqueous ammonia solution, c) separating the reaction mixture from step b) into an aqueous phase and an organic phase, d) neutralizing the other part of the acid, present in the organic phase, with aqueous alkali metal hydroxide solution, e) separating the reaction mixture from step d) into an aqueous phase and an organic phase, f) treating the aqueous phase obtained in step c) or optionally the combined aqueous phases from steps c) and e) with at least one oxide or hydroxide of an alkaline earth metal, g) removing the ammonia obtained in step f).
Abstract:
A reactor (1) for preparing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a solid catalyst, which reactor has a bundle of parallel catalyst tubes (2) aligned in the longitudinal direction of the reactor whose ends are fixed in tube plates (3) and have a cap (4) at each end of the reactor (1), and has deflection plates (6) which are aligned perpendicular to the longitudinal direction of the reactor in the intermediate space (5) between the catalyst tubes (2) and leave free passages (7) located alternately opposite one another on the interior wall of the reactor, and in which the catalyst tubes (2) are charged with the solid catalyst, the gaseous reaction mixture is passed from one end of the reactor via one cap (4) through the catalyst tubes (2) and is taken off from the opposite end of the reactor (1) via the second cap (4) and a liquid heat transfer medium is passed through the intermediate space (5) around the catalyst tubes (2), where the reactor (1) has no tubes in the region of the passages (7), is proposed.