Abstract: The present invention relates to a process for working up organic secondary components which are formed in the one-stage or two-stage nitration of toluene to dinitrotoluene. These organic secondary components are present in the acidic and alkaline waste water from the dinitrotoluene washing step and in the aqueous distillate from the sulfuric acid concentration step, together with small amounts of mononitrotoluene and dinitrotoluene. This process comprises a) combining the acidic and alkaline waste waters from the washing step and the aqueous distillate from the sulfuric acid concentration step such that the resulting mixture has a pH below 5, b) separating the aqueous and organic phases which form by phase separation, and c) recycling the organic phase from step b) into the nitration process.

Abstract: The present invention relates to a process for working up or treating aqueous waste waters which are formed during the nitration of toluene to dinitrotoluene with nitrating acid. These aqueous waste waters containing acidic wash water and alkaline wash water from the dinitrotoluene washing step, and distillate from the sulfuric acid concentration step. The process comprises, a) combining the acidic and alkaline waste waters from the washing step and the aqueous distillate from the sulfuric acid concentration step such that the resulting mixture has a pH below 5, b) separating the aqueous and organic phases which are formed by phase separation, c) subjecting the aqueous phase from b) to an extraction step, wherein d) the organic components contained in the aqueous phase from c) are extracted with toluene, and e) introducing the toluene phase enriched with the organic components into the toluene nitration.

Abstract: The present invention relates to a process for working up or treating aqueous waste waters which are formed during the nitration of toluene to dinitrotoluene with nitrating acid. These aqueous waste waters containing acidic wash water and alkaline wash water from the dinitrotoluene washing step, and distillate from the sulfuric acid concentration step.

Abstract: The invention relates to a process for the production of dinitrotoluene by the two-stage nitration of toluene.

Abstract: The present invention relates to a process for working up organic secondary components which are formed in the one-stage or two-stage nitration of toluene to dinitrotoluene. These organic secondary components are present in the acidic and alkaline waste water from the dinitrotoluene washing step and in the aqueous distillate from the sulfuric acid concentration step, together with small amounts of mononitrotoluene and dinitrotoluene.

Abstract: Aromatic amines are produced from aromatic hydrocarbons by

Abstract: High boiling contaminants such as chloro-aromatic compounds are removed from a gas by compressing the gas containing the contaminant, cooling the compressed gas to reduce the temperature of the gas to at least 20° C. above the outlet temperature of a second cooling stage but above the freezing point of the highest melting compound in the first cooling stage, further cooling the gas in a second cooling stage to at least −20° C., returning cooled gas from the second cooling stage to the first cooling stage, and recovering condensate streams which contain the contaminant compound from the first and second cooling stages. An apparatus suitable for carrying out this process is also disclosed. The process of the present invention is particularly useful for removing chloro-aromatic compounds from anhydrous hydrogen chloride gas.

Abstract: Toluene diisocyanate is recovered from a crude distillation feed comprising less than 2% by weight of phosgene by

Abstract: High boiling contaminants such as chloro-aromatic compounds are removed from a gas by compressing the gas containing the contaminant, cooling the compressed gas to reduce the temperature of the gas to at least 20° C. above the outlet temperature of a second cooling stage but above the freezing point of the highest melting compound in the first cooling stage, further cooling the gas in a second cooling stage to at least −20° C., returning cooled gas from the second cooling stage to the first cooling stage, and recovering condensate streams which contain the contaminant compound from the first and second cooling stages. An apparatus suitable for carrying out this process is also disclosed. The process of the present invention is particularly useful for removing chloro-aromatic compounds from anhydrous hydrogen chloride gas.

Abstract: Process for the purification of toluenediisocyanate from a crude distillation feed comprising 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.

Abstract: High boiling contaminants such as chloro-aromatic compounds are removed from a gas by compressing the gas containing the contaminant, cooling the compressed gas to reduce the temperature of the gas to at least 20° C. above the outlet temperature of a second cooling stage but above the freezing point of the highest melting compound in the first cooling stage, further cooling the gas in a second cooling stage to at least −20° C., returning cooled gas from the second cooling stage to the first cooling stage, and recovering condensate streams which contain the contaminant compound from the first and second cooling stages. An apparatus suitable for carrying out this process is also disclosed. The process of the present invention is particularly useful for removing chloro-aromatic compounds from anhydrous hydrogen chloride gas.

Abstract: Toluylene diisocyanate is produced by nitration of toluene toy yield dinitrotoluene, hydrogenation of the dinitrotoluene, optionally in the presence of a solvent or diluent, to yield a crude solution of toluylene diamine and reaction water, processing the crude solution of toluylene diamine and water to yield an intermediate mixture of toluylene diamine and water wherein the processing is interrupted to result in a water content of about 1-40% by weight, preferably about 2-10% by weight of the intermediate mixture, transporting this intermediate mixture from a first production facility to a second production facility, whereat the intermediate mixture of TDA and water is completed to yield dry toluylene diamine of commercial quality, and followed by phosgenation of the toluylene diamine to give toluylene diisocyanate. It is optional to additionally process the dry toluylene diamine prior to phosgenation.

Abstract: A mixture of materials having different boiling points is separated into fractions having different boiling points. The separated fraction containing the desired product is stripped using the vapors of a lower boiling fraction. The process of the present invention is particularly useful for recovering a desired isomer or isomer mixture from a technical mixture obtained during production of an aromatic amine such as toluenediamine. Little or no unwanted isomer or by-product is present in the isomer or isomer mixture product of this process.

Abstract: Toluylene diisocyanate is produced by nitration of toluene toy yield dinitrotoluene, hydrogenation of the dinitrotoluene, optionally in the presence of a solvent or diluent, to yield a crude solution of toluylene diamine and reaction water, processing the crude solution of toluylene diamine and water to yield an intermediate mixture of toluylene diamine and water wherein the processing is interrupted to result in a water content of about 1-40% by weight, preferably about 2-10% by weight of the intermediate mixture, transporting this intermediate mixture from a first production facility to a second production facility, whereat the intermediate mixture of TDA and water is completed to yield dry toluylene diamine of commercial quality, and followed by phosgenation of the toluylene diamine to give toluylene diisocyanate. It is optional to additionally process the dry toluylene diamine prior to phosgenation.

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: Crude polyisocyanates are purified by extraction at a temperature from 80.degree. to 180.degree. C. to form a two-phase system. The phases are separated and the phase made up of purified polyisocyanate and solvent is cooled to a temperature which is at least 50.degree. C. below the extraction temperature. Upon cooling, a second two-phase system forms. Purified polyisocyanate containing residual solvent is recovered upon separation of these phases. Solvent in which polyisocyanate is present that is reclaimed during this process may be reused in subsequent extractions. The purified polyisocyanates have a viscosity which is lower than that of crude polyisocyanates having substantially the same isocyanate content and average functionality. These purified polyisocyanates are useful in the production of polyurethane foams and moldings as well as adhesives and coatings.

Abstract: Polyisocyanates are produced by reacting a polyamide solution with a phosgene solution. After the product polyisocyanate has been recovered, the solvent or a portion of the solvent employed is treated with crosslinked polymers insoluble in the solvent which polymers contain primary and/or secondary alcoholic hydroxyl groups and/or primary and/or secondary amino groups. After treatment, the polymer and any reaction products are removed. The solvent may then be reused. Preferred solvents are chlorobenzene and o-dichlorobenzene. The preferred polymers are bead polymers or bead copolymers of (meth)acrylic acid or styrene/divinyl benzene copolymer.

Abstract: The present invention is directed to a process for the production of polyamines of the diphenylmethane series having a high diamine content and a low 2,2'-diamino-diphenylmethane content by condensing aniline with formaldehyde in the presence of hydrochloric acid as catalyst, neutralizing the acid catalyst at the end of the condensation reaction and working up the polyamine mixture thus obtained by distillation, characterized in that(a) in a first reaction stage, from 2.0 to 3.5 moles of aniline are reacted with 1 mole of formaldehyde in the presence of hydrochloric acid or a condensation product produced from 2.0 to 3.5 moles of aniline and 1 mole of formaldehyde in the absence of acid catalyst is reacted in the presence of hydrochloric acid at a degree of protonation maintained at 40 to 60% at temperatures below 50.degree. C.

Abstract: Stable non-aqueous dispersions having a high solids content which can rapidly be dissolved in water without forming lumps consist of water-soluble polymers, dispersing oil, sorbitan fatty acid esters and ehtoxylation products of fatty acids and/or fatty alcohols. The dispersions may be used, for example, as flocculating agents, retention agents, drilling auxiliaries and flooding additive.