Abstract: The invention relates to a process for preparing isocyanates by reacting amines with phosgene in the gas phase in a reaction zone, with the reaction mixture being passed through a zone into which a liquid is sprayed to stop the reaction, wherein the reaction mixture is passed through a zone having a reduced flow cross section between the reaction zone and the zone into which the liquid is sprayed.

Abstract: Isocyanates are produced by reacting an organic amine with phosgene in process which includes at least three stages. The first stage is carried out in a dynamic mixer. The second stage is carried out in at least one reactor. The third stage is carried out in at least one material separating apparatus. The pressure in the reactor of the second stage must be greater than or equal to the pressure in the dynamic mixer. The pressure in the third stage material separating apparatus must be lower than the pressure in the second stage reactor.

Abstract: The invention relates to a process for the production of toluene diisocyanate, in which the crude toluenediamine obtained from the hydrogenation is purified and then phosgenated. The purification step reduces the total amount of cyclic ketones to less than 0.1% by weight, based on 100% by weight of the toluenediamine.

Abstract: A process for the coupled production of chlorine and isocyanates in which the sulfuric acid used for both processes is combined after use, concentrated together and returned to one or both processes.

Abstract: Isocyanates, preferably diisocyanates and polyisocyanates of the diphenylmethane series (MDI), are produced by reaction of amines dissolved in a solvent with phosgene in the same solvent to form the corresponding isocyanates. Hydrogen chloride and excess phosgene are subsequently removed from the reaction mixture to obtain a crude isocyanate-containing solution. Subsequently, the crude isocyanate-containing solution is separated by distillation into isocyanates and solvent. The solvent is recycled and used for the production of solutions of the amines and of phosgene. The solvent being recycled is treated to reduce the phosgene and diisocyanate contents before being used for the production of the solution of the amine.

Abstract: The invention provides a process for the preparation of polyamines of the diphenylmethane series. This process comprises a) reacting aniline and formaldehyde in a molar ratio of 1.5:1 to 6:1, in the presence of an acid catalyst at temperatures of 20° C. to 100° C., in which the water content in the acid reaction mixture is <20 wt. % and a degree of protonation of <15% is established, and b) increasing the temperature of the reaction to a temperature of 110° C. to 250° C. when the ratio of the weight contents of p-aminobenzylaniline to 4,4?-MDA in the reaction mixture falls below a value of 1.00.

Abstract: The invention relates to an improved process for the production of isocyanates by the reaction of an amine or a mixture of two or more amines with phosgene, the improvement involving the phosgene containing less than about 100 ppm of sulfur in elemental or bound form. The inventive process yields light-colored isocyanates that are suitable for the production of polyurethanes or their precursors (e.g. prepolymers) without the treatment processes heretofore required.

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: In a process for preparing isocyanates by reacting the corresponding primary amines with phosgene in an inert solvent, use is made of from 0.01 to 50 mol % of a sulfonamide, based on the total amount of primary amine and isocyanate formed in the reaction solution.

Abstract: Di- and polyamines of the diphenylmethane series are prepared by a) mixing a first portion of aniline with an acid catalyst, b) mixing a second portion of aniline with formaldehyde, and c) mixing and reacting the mixtures prepared in each of steps a) and b). The diamines produced by this process may then be phosgenated to produce the corresponding di-/polyisocyanate.

Abstract: The invention relates to a process for the production of di- and polyisocyanates of the diphenylmethane series and mixtures thereof, in which aniline and formaldehyde are reacted in the presence of an acid catalyst to form di- and polyamines of the diphenylmethane series; the di- and polyamines of the diphenylmethane series are phosgenated, optionally in the presence of a solvent, to obtain a crude di- and polyisocyanate; from the crude di- and polyisocyanate, at least one fraction containing at least 5 wt. % 3-ring and multi-ring MDI and at least one fraction containing at least 95 wt. % 2-ring MDI are separated by distillation, and the acidities of the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt. % 2-ring MDI are determined analytically; and an acidic compound is added to the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt.

Abstract: The present invention relates to a process for the preparation of di- and polyamines of the diphenylmethane series, and to the preparation of di- and poly-isocyanates of the diphenylmethane series from these di- and poly-amines. The di- and poly-amines of the diphenylmethane series are prepared by the reaction of aniline and formaldehyde in the presence of hydrochloric acid. In with the present invention, the hydrochloric acid employed contains less than 0.001 wt. % of metal ions which are divalent and/or more than divalent.

Abstract: The invention provides an optical material being excellent in balance between the heat resistance, Abbe number and refractive index by providing a compound represented by the general formula (1): in the formula, k and n representing integers of 0 to 2 and 0 to 1, respectively, with the proviso that k and n are not simultaneously zero, and k=0 meaning that —(CH2)k- is not included in the formula.

Abstract: Process for the purification of toluenediisocyanate from a crude distillation feed which includes toluenediisocyanate, an organic solvent and less than 2% by weight phosgene by separating the crude distillation feed in a dividing-wall distillation column into at least four product fractions P1–P4. P1 is a phosgene enriched low-boiler product, P2 is a solvent-enriched product, P3 is a high boiler enriched bottoms and P4 is a toluenediisocyanate product stream.

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: Toluene diisocyanate is recovered from a crude distillation feed containing less than 2% by weight of phosgene by (a) fractionating the crude distillation feed containing less than 2% by weight of phosgene to remove the solvent and optionally the reaction residues to produce a crude toluene diisocyanate feed containing less than 20% by weight of solvent and (b) separating the crude toluene diisocyanate feed containing less than 20% by weight of solvent in a divided-wall distillation column into four product fractions P1–P4. P1 is a vapor phase low-boiler and solvent-enriched gas stream, P2 is a low-boiler and solvent-enriched product, P3 is a high boiler-enriched bottoms product containing toluene diisocyanate and P4 is a toluene diisocyanate product stream lean in low-boilers, high-boilers and reaction residues.

Abstract: The invention relates to a method for producing isocyanates by reacting primary amines with phosgene in the gaseous phase. Said method is characterized in that the reaction of amine and phosgene occurs in a reaction channel, the internal dimensions of which have a width/height ratio of at least 2/1.

Abstract: A preparation process of 3-chloro-5-nitrotoluene is provided in mild conditions. It is a process for preparing 3-chloro-5-nitrotoluene, which involves the steps of reacting 2-methyl-4-nitroaniline with a chlorinating agent such as 5-butyl hypochlorite in a neutral condition to obtain 2-chloro-4-nitro-6-methylaniline and deaminating the 2-chloro-4-nitro-6-methylaniline to obtain 3-chloro-5-nitrotoluene.

Abstract: In a process for preparing isocyanates by reacting the corresponding primary amines with phosgene in an inert solvent, use is made of from 0.01 to 50 mol % of a sulfoxide, a sulfone or a mixture thereof, based on the total amount of primary amine and isocyanate formed in the reaction solution.

Abstract: The invention relates to a method of producing polyisocyanates of the diphenylmethane series including the steps of a) reacting aniline and formaldehyde in the presence of HCl to provide a product mixture containing polyamines of the diphenylmethane series, HCl, aniline and water; b) removing excess aniline and water by distillation to provide a product mixture comprising polyamines of the diphenylmethane series, HCl, no more than 10 wt. % aniline based on the polyamines, and no more than 5 wt. % water based on the polyamines; and c) phosgenating the product mixture in (b).

Abstract: A fraction of diisocyanates of the diphenylmethane series containing at least 95 wt. % binuclear methylenediphenyl diisocyanate is obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to produce diamines and polyamines of the diphenylmethane series containing binuclear methylenediphenyl diamine, b) phosgenating the diamines and polyamines produced in a), optionally in the presence of a solvent, to produce a crude diisocyanate and polyisocyanate, and c) separating a fraction containing at least 95 wt. % binuclear methylenediphenyl diisocyanate with a 4,4?-MDI content of over 60 wt. %, a 2,4?-MDI content of 4 to 35 wt. % and a 2,2?-MDI content of 0.01 to 10 wt. %, relative to the mass of the fraction, and a maximum of 20 ppm phenyl isocyanate and optionally a maximum of 50 ppm solvent from the crude diisocyanate and polyisocyanate produced in b) in a single distillation step with optional upstream and/or downstream separation of low-boiling components.

Abstract: The present invention relates to a process for the production of an isocyanate corresponding to the formula R(NCO)n wherein R represents a (cyclo)aliphatic or aromatic hydrocarbon residue having up to 15 carbon atoms, preferably 4 to 13 carbon atoms, provided that there are at least 2 carbon atoms arranged between each of the nitrogens and n represents the number 2 or 3, by a) separately heating an amine corresponding to the formula R(NH2)n, wherein R and n are as previously defined, in vapor form, optionally diluted with an inert gas or the vapors of an inert solvent, and phosgene to temperatures of 200° C. to 600° C.

Abstract: The present invention relates to a process for the manufacture of diisocyanates by phosgenation of the corresponding diamines in which the vaporous diamines, optionally rarefied with an inert gas or with the vapors of an inert solvent, and phosgene are heated separately to temperatures of about 200° C. to about 600° C. and mixed and reacted in a tube reactor characterized in that a number n?2 of nozzles directed parallel to the axis of the tube reactor are arranged in the tube reactor, the diamine-containing stream being fed into the tube reactor through the n nozzles and the phosgene stream being fed into the tube reactor through the remaining free space.

Abstract: The present invention relates to a process for preparing arylsulfonyl isocyanates by reacting an arylsulfonamide with phosgene in the presence of a catalytically effective amount of an alkyl isocyanate.

Abstract: The invention relates to a process for the preparation of isocyanates in the gas phase, in which the possibilities for back-mixing and byproduct formation are reduced by improving the mixing of the starting materials in a tubular reactor.

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: In a process for mixing reactant streams (1, 2; 5) to produce a product stream (10) using a mixing configuration (15, 16) having a number of reactant feed points, an excess component stream of one reactant is divided into two reactant substreams (1, 2) and fed into the suction region (3, 4) of a mixing space (12) at right angles to a deficient component (5) entering the mixing space (12).

Abstract: Starting material streams are mixed in a mixer (13) for the phosgenation of amines by a process in which the reaction product (3) is removed in a closed loop and the starting material streams (1.2) contain organic solvents. The main streams (1.1, 2.1) and/or part-streams (1.2, 2.2) of the starting materials (1, 2) come into contact with one another according to the countercurrent principle.

Abstract: In a process for preparing isocyanates by reacting the corresponding primary amines with phosgene in an inert solvent, use is made of from 0.01 to 50 mol % of a sulfonamide, based on the total amount of primary amine and isocyanate formed in the reaction solution.

Abstract: In a process for preparing isocyanates by reacting the corresponding primary amines with phosgene in an inert solvent, use is made of from 0.01 to 50 mol % of a phosphine oxide, based on the total amount of primary amine and isocyanate formed in the reaction solution.

Abstract: The invention relates to a process for the production of isocyanates by reaction of primary amines with phosgene, in which isocyanate is used as solvent, wherein some or all of isocyanate used as solvent is added to the reaction mixture only after the amine and phosgene have been physically combined.

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: In a process for preparing isocyanates by reacting the corresponding primary amines with phosgene in an inert solvent, use is made of from 0.01 to 50 mol % of a sulfoxide, a sulfone or a mixture thereof, based on the total amount of primary amine and isocyanate formed in the reaction solution.

Abstract: A process for the purification of toluenediisocyanate by fractionating a crude distillation feed containing toluenediisocyante, an organic solvent and less than 2% by weight of phosgene in a heat integrated system having an upstream distillation column, an interchanger and a downstream distillation column which are connected in series. The vapor which is recovered from the upstream distillation column is used to reboil the bottoms product of the downstream distillation column or the feed to the downstream distillation column in the interchanger. The crude distillation feed comprising less than 2% by weight of phosgene is fractionated into three product fractions P1-P3 and optionally a fourth fraction P4. P1 is a noncondensible gas stream enriched with phosgene and/or low-boilers. P2 is a solvent-enriched product. P3 is a high boiler enriched bottoms product comprising toluenediisocyanate, and P4 is a toluenediisocyanate enriched stream lean in highboilers and reaction residues.

Abstract: Isocyanates are produced in the gas phase in a manner such that temperature fluctuations over time and temperature distribution asymmetry are prevented. In this improved process, performance of the reaction in tubular reactors is accomplished by flow-related measures such as homogenization and centering of the educt streams. The formation of polymeric secondary products, which result in baked-on deposits in the reactor and a reduction in reactor service life, is consequently prevented.

Abstract: The present invention provides a process for quenching a gaseous reaction mixture during the phosgenation of diamines in the gas phase to produce diisocyanates. The gaseous reaction mixture contains at least a diisocyanate, phosgene and hydrogen chloride. The quenching liquid is injected into the gas mixture continuously flowing out of a cylindrical reaction zone into the downstream cylindrical quenching zone with the aid of at least two spray nozzles which are arranged at the entrance to the quenching zone at equal distances along the circumference of the quenching zone.

Abstract: The invention relates to a process for the production of isocyanates by reaction of primary amines with phosgene, in which isocyanate is used as solvent, wherein some or all of isocyanate used as solvent is added to the reaction mixture only after the amine and phosgene have been physically combined.

Abstract: MDI is prepared by a process comprising the following steps:

Abstract: A preparation process of 3-chloro-5-nitrotoluene is provided in mild conditions. It is a process for preparing 3-chloro-5-nitrotoluene, which comprises reacting 2-methyl-4-nitroaniline with a chlorinating agent such as 5-butyl hypochlorite in a neutral condition to obtain 2-chloro-4-nitro-6-methylaniline and deaminating the 2-chloro-4-nitro-6-methylaniline to obtain 3-chloro-5-nitrotoluene.

Abstract: The present invention relates to novel aromatic isocyanates obtained by partially hydrogenating naphthalene as well as the processes for preparing the same, and to their use as an isocyanate component in the production of polyurethanes.

Abstract: A description is given of polyisocyanates of the formula I in which R and R′ are identical or different and are alkyl groups having 1-4 carbon atoms and n is on average from 1.5 to 5 and also of a process for preparing these polyisocyanates in which a polyamine of the formula II in which R, R′, and n are as defined above, is reacted with phosgene. The new polyisocyanates are suitable for producing crosslinked polyurethanes from reaction mixtures with low solvent content and for producing coating compositions or adhesives. Also described are the coating compositions and adhesives, and their use.

Abstract: Polyisocyanates of the diphenylmethane series are produced by a) reacting aniline and formaldehyde in the presence of an acidic catalyst to produce a polyamine, b) neutralizing the reaction mixture from step a) with a base at a temperature of more than 110° C. or neutralizing the reaction mixture from step a) with a base and heating the neutralized mixture to a temperature of more than 110° C., and c) phosgenating the polyamine from step b) to convert it to the corresponding polyisocyanate.

Abstract: The present invention provides a process for quenching a gaseous reaction mixture during the phosgenation of diamines in the gas phase to produce diisocyanates. The gaseous reaction mixture contains at least a diisocyanate, phosgene and hydrogen chloride. The quenching liquid is injected into the gas mixture continuously flowing out of a cylindrical reaction zone into the downstream cylindrical quenching zone with the aid of at least two spray nozzles which are arranged at the entrance to the quenching zone at equal distances along the circumference of the quenching zone.

Abstract: The present invention relates to a novel process for preparing (cyclo)aliphatic diisocyanates and triisocyanates by phosgenation of (cyclo)aliphatic diamines and triamines in the gas phase by accelerating the flow of at least one of reactants in the region where the reactants are mixed.

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

Abstract: The present invention relates to a process for the preparation of aliphatic, cycloaliphatic, araliphatic and aromatic mono- and oligoisocyanates by phosgenation of the corresponding primary amines at atmospheric pressure, which comprises a) introducing a catalytic amount of a monoisocyanate (isocyanate a) into an inert solvent together with phosgene; b) adding the primary amine, and c) reacting the resulting reaction mixture with phosgene.

Abstract: A process for working up distillation residues from the synthesis of tolylene diisocyanate by reaction of the distillation residues with water comprises reacting the TDI distillation residues with water in a continuous or semicontinuous process in a backmixed reactor in the presence of hydrolysate.

Abstract: Disclosed herein is a process for preparing a reaction product containing methylene diphenylamine, comprising reacting aniline and formaldehyde in the presence of an acid catalyst wherein the acid level of the resulting reaction mixture is reduced during digestion of the reaction mixture.

Abstract: Isocyanates are produced in the gas phase in a manner such that temperature fluctuations over time and temperature distribution asymmetry are prevented. In this improved process, performance of the reaction in tubular reactors is accomplished by flow-related measures such as homogenization and centering of the educt streams. The formation of polymeric secondary products, which result in baked-on deposits in the reactor and a reduction in reactor service life, is consequently prevented.

Abstract: Polyisocyanates of the diphenyl methane series having reduced color values are obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to form a polyamine, b) neutralizing the reaction mixture containing polyamine with a base, c) separating the neutralized mixture into the aqueous and the organic phases, d) adding a base to the organic phase and then e) phosgenating the resulting polyamine to produce the corresponding polyisocyanate.