Abstract: Process for preparing polyoxymethylene dimethyl ethers having ?3 oxymethylene units (OMEn?3), comprising the steps: (i) introduction of formaldehyde, methanol and water into a reactor R and reaction to give a reaction mixture containing formaldehyde, water, methylene glycol, polyoxymethylene glycols, methanol, hemiformals, methylal (OMEn=1) and polyoxymethylene dimethyl ethers (OMEn>1); (ii) introduction of the reaction mixture into a reactive distillation column K1 and separation into a low boiler fraction F1 containing formaldehyde, water, methylene glycol, polyoxymethylene glycols, methanol, hemiformals, methylal (OMEn=1) and polyoxymethylene dimethyl ethers having from 2 to 3 oxymethylene units (OMEn=2-3) and a high boiler fraction F2 containing polyoxymethylene dimethyl ethers having more than two oxymethylene units (OMEn?3).

Abstract: Process for preparing polyoxymethylene dimethyl ethers having ?3 oxymethylene units (OMEn?3), comprising the steps: (i) introduction of formaldehyde, methanol and water into a reactor R and reaction to give a reaction mixture containing formaldehyde, water, methylene glycol, polyoxymethylene glycols, methanol, hemiformals, methylal (OMEn=1) and polyoxymethylene dimethyl ethers (OMEn>1); (ii) introduction of the reaction mixture into a reactive distillation column K1 and separation into a low boiler fraction F1 containing formaldehyde, water, methylene glycol, polyoxymethylene glycols, methanol, hemiformals, methylal (OMEn=1) and polyoxymethylene dimethyl ethers having from 2 to 3 oxymethylene units (OMEn=2-3) and a high boiler fraction F2 containing polyoxymethylene dimethyl ethers having more than two oxymethylene units (OMEn?3).

Abstract: A process for the preparation of mononitroaromatics and dinitroaromatics, in which a hydrate melt of at least one metal nitrate M(NO3)3 is used as a nitrating medium, it being possible for M to be the metals Fe, Cr, Y, La, Ce, Al, Bi and In, and the metal nitrate having a water content of from 4 to 9 mol of water per M(NO3)3, leads to simplifications of the process and improved yields.

Abstract: The present invention comprises a process for purifying isocyanate-comprising residues.

Abstract: A process for the preparation of mononitroaromatics and dinitroaromatics, in which a hydrate melt of at least one metal nitrate M(NO3)3 is used as a nitrating medium, it being possible for M to be the metals Fe, Cr, Y, La, Ce, Al, Bi and In, and the metal nitrate having a water content of from 4 to 9 mol of water per M(NO3)3, leads to simplifications of the process and improved yields.

Abstract: The invention relates to a process for preparing isocyanates by reacting the corresponding amines with phosgene in the gas phase, optionally in the presence of an inert medium, in which phosgene and amine are first evaporated and then superheated further to reaction temperature, and the superheated phosgene and amine are mixed and fed to a reactor in which the phosgene and the amine are converted to the isocyanate, wherein the residence time of the phosgene at temperatures greater than 300° C. is not more than 5 s, and/or the temperature of heat transfer surfaces in contact with phosgene is not more than 20 K above the phosgene temperature to be established. The invention further relates to an apparatus for preparing isocyanates by reacting the corresponding amines with phosgene in the gas phase.

Abstract: A process for coproducing di- and/or polyisocyanates and glycols, comprising process stages A, B, C and E for preparing glycols and process stages A, C, D, E, F and G for preparing di- and/or polyisocyanates, which comprises accomplishing the material coupling via the separation of the reaction mixture obtained in process stage A into process stages B and C, by in process stage A, reacting an aqueous alkylene oxide with carbon dioxide to give a reaction mixture comprising alkylene carbonate, hydrolyzing a portion of the alkylene carbonate-comprising reaction mixture obtained in process stage A to glycol in process stage B, dewatering the remaining alkylene carbonate-comprising stream of the reaction mixture from process stage A in process stage C, in process stage D, synthesizing amine by hydrogenating an aromatic nitro compound or a nitrile, in process stage E, transesterifying the dewatered alkylene carbonate-comprising mixture from process stage C with a monohydroxy alcohol to give the corresponding dia

Abstract: The present invention relates to a process for preparing polyisocyanates from natural raw material sources, in which a composition comprising low molecular weight aromatics which comprise at least one hydroxy group or at least one alkoxy group per molecule (oxyaromatics) is produced from a biomass material, these oxyaromatics are converted into the corresponding aromatic amines and, optionally after condensation with formaldehyde, reacted further with phosgene to give compounds comprising isocyanate groups.

Abstract: The invention relates to a multistage process for the continuous preparation of organic, distillable polyisocyanates, preferably diisocyanates, particularly preferably aliphatic or cycloaliphatic diisocyanates, by reaction of the corresponding organic polyamines with carbonic acid derivatives and alcohols to form low molecular weight monomeric polyurethanes and thermal dissociation of the latter, in which the polyisocyanates produced and unusable residues are separated off at particular stages of the reaction and reusable by-products and intermediates are recirculated to preceding stages.

Abstract: The present invention relates to a process for preparing an isocyanate, comprising hydrogenating a mixture (Gi) comprising an amine in the presence of a hydrogenation catalyst comprising copper to obtain a mixture (Gii) comprising the amine, and reacting the mixture (Gii) with phosgene to obtain a mixture (Giii) comprising the isocyanate. The present invention further relates to the isocyanate preparable by this process.

Abstract: The present invention accordingly provides a process for preparing light-colored polyphenylene-polymethylene polyisocyanates comprising the steps (a) providing an amount of chlorine, (b) separating the chlorine provided in the step (a) to obtain a first chlorine fraction having a content of free and bound bromine and iodine of <50 ppm and a second chlorine fraction having an increased content of free and bound bromine and iodine that depends on the original amount of bromine and iodine in the chlorine provided in step (a) and the separation split, (c) reacting carbon monoxide with at least a portion of the first chlorine fraction to form a first phosgene fraction, (d) reacting carbon monoxide with at least a part of the second chlorine fraction to form a second phosgene fraction, (e) reacting at least a portion of a first phosgene fraction with at least one amine of the diphenylmethane diamine series (MDA) to form the corresponding polyphenylene-polymethylene polyisocyanate (PMDI), and (f) reacting at leas

Abstract: Process for preparing aromatic isocyanates by reacting the corresponding formamides with an oxygen-comprising gas over noble metal catalysts at temperatures of from 300 to 600° C. and a contact time of from 1 to 1000 ms, wherein: a. the formamide is vaporized before entering the reaction zone, b. the reaction mixture obtained is quenched with an alcohol-comprising quenching liquid and c. the urethane formed is dissociated into isocyanate and alcohol.

Abstract: The invention relates to a process for preparing isocyanates by reacting the corresponding amines with phosgene in the liquid phase, if appropriate in the presence of at least one inert medium, in which the amine and the phosgene are first mixed in a mixing chamber (1) to give a reaction mixture and the reaction mixture is fed to a reactor, the amine being added through an orifice (3) arranged coaxially to the mixing chamber (1) and the phosgene being added through feed orifices (5) in at least two planes (7, 9) arranged at right angles to the axis (11) of the mixing chamber (1), or the phosgene being added through the orifice (3) arranged coaxially to the mixing chamber and the amine through the feed orifices (5) in at least two planes (7, 9) arranged at right angles to the axis (11) of the mixing chamber (1). At least one plane (9) is arranged upstream and at least one plane (7) downstream of the orifice (3) arranged coaxially to the mixing chamber (1) in main flow direction of the reaction mixture.

Abstract: A process is proposed for preparing isocyanates by thermally cleaving carbamates to obtain a carbamate cleavage gas comprising the corresponding isocyanate and the corresponding alcohol, which comprises quenching the carbamate cleavage gas in the presence of an ether which functions as an inhibitor for the reverse reaction of the isocyanate with the alcohol.

Abstract: Process for preparing isocyanates by phosgenation of amines, wherein phosgene and amine are brought into contact in at least 2 mixing chambers connected in parallel.

Abstract: The present invention relates to a process for the production of isocyanates, preferably diisocyanates and polyisocyanates of the diphenylmethane series (MDI), by reacting an amine with phosgene in the liquid phase or in the gas phase to form the corresponding isocyanates, subsequent removal of the solvent in at least two steps to obtain at least two solvent streams, individual treatment of the at least two solvent streams, and recirculation of at least a portion of the solvent streams.

Abstract: The present invention relates to a process for preparing light-colored polyphenylene-polymethylene-polyisocyanate (PMDI), comprising the steps (a) providing carbon monoxide and chlorine, (b) reacting carbon monoxide with chlorine to form phosgene, (c) reacting the phosgene from step (b) with at least one primary amine with the exception of mono- and polyphenylene-polymethylene polyamines with an excess of phosgene to form an at least one isocyanate containing reaction solution, and hydrogen chloride, (d) separating excess phosgene from the isocyanate-containing reaction solution obtained in step (c), (e) providing at least one polyphenylene-polymethylene polyamine, and (f) reacting at least a portion of the phosgene separated in step (d) with the at least one polyphenylene-polymethylene polyamine to form the light-colored polyphenylene-polymethylene polyisocyanate.

Abstract: The invention relates to a process for preparing methylenediphenyldiamine (MDA), comprising the following steps a) to c): a) converting formaldehyde and aniline to aminal b) removing water from the aminal obtained in step a) to establish a water content of 0 to 5% by weight based on the aminal, and c) adding an acidic catalyst to the aminal having a water content of 0 to 5% by weight, which comprises using formaldehyde in step a) in the form of highly concentrated formaldehyde with a CH2O content of >50% by weight and preparing the formaldehyde by oxidative dehydrogenation from methanol.

Abstract: The invention relates to a process for preparing isocyanates and/or polyisocyanates by reacting the corresponding amines with phosgene, optionally in the presence of an inert medium, in a reactor (1), a first reactant stream comprising the amine being supplied to the reactor (1) in liquid form, and a second reactant stream comprising the phosgene being supplied to the reactor in gaseous form. The reactor is a centrifugal reactor (1) having a packing (9) which rotates about a central axis (7) in a housing (13), the first reactant stream and the second reactant stream being supplied to the rotating packing (9) such that the reactant streams are mixed due to the centrifugal force in the rotating packing (9) and are transported outward, the mixing in the rotating packing (9) resulting in reaction of the phosgene with the amine to give the corresponding isocyanate or polyisocyanate.

Abstract: The invention relates to a process for the preparation of formamides by reacting aromatic amines with a formic acid ester in the presence of a catalyst, wherein the catalyst is a phosphorus-containing acid or a Lewis-acidic metal salt.