Bayer Aktiengesellschaft

Bayer Materialscience Ag

Covestro Deutschland Ag

Bayer Intellectual Property Gmbh

Klaus Biskup

Friedhelm Steffens

Rainer Bruns

Fritz Pohl

Wolfgang Lorenz

Berthold Keggenhoff

Herbert Stutz

Lars Padeken

Bernd Pennemann

Volker Michele

Andreas Karl Rausch

Hartmut Hetzel

Dieter Grenner

Christian Konig

Peter Fuhrmann

Eckart Waldau

Christian Six

Wolfgang Ebner

Peter Keldenich

Andreas Rausch

Meta-toluene-diisocyanate is produced by reacting meta-toluenediamine with phosgene in the gas phase. The meta-toluenediamine to be vaporized for use in this phosgenation process must contain less than 0.5 wt. % of toluenediamine residue, a total of less than 0.2 wt. % of ammonia and cycloaliphatic amines, and less than 20 ppm of heavy metals. At least 0.1 wt. % of the liquid meta-toluenediamine being to be vaporized must not be vaporized. This non-vaporized content of the meta-toluenediamine must not be fed to the phosgenation reactor.

Process for the preparation of isocyanates in the gas phase

Aromatic isocyanates are produced by reacting one or more aromatic primary amines with phosgene in the gas phase. The phosgene and primary aromatic amine(s) are reacted at a temperature above the boiling temperature of the amine(s) in a reactor having a reaction space which is essentially rotationally symmetric to the direction of flow. The flow fate, averaged over the cross-section, of the reaction mixture along the axis of the essentially rotationally symmetric reaction space in the section of the reaction space in which the conversion of the amine groups into isocyanate groups is between 4 and 80% is not more than 8 m/sec. The flow rate averaged over the cross-section of the reaction mixture along the axis of the essentially rotationally symmetric reaction space in the section of the reaction space in which the conversion of the amine groups into isocyanate groups is 4 to 80% is always below the flow rate averaged over the cross-section at the start of this section.

Aromatic diisocyanates are produced by reacting in the gas phase the corresponding primary aromatic diamine with phosgene. The phosgene and the primary aromatic diamine are reacted within a mean residence time of from 0.05 to 15 seconds. The aromatic diamine used contains less than 0.05 mole % overall of aliphatic amine containing no keto groups, per mole of primary amino groups.

Process for the production of aromatic diisocyanates in the gas

Isocyanates are produced by reaction of primary amines with phosgene in the gas phase. In this process, the reaction is terminated by guiding the reaction mixture from the reaction chamber through a cooling stretch into which liquids are injected. Direct cooling takes place in the cooling stretch in one stage in two or more cooling zones connected in series.

An isocyanate is produced by reacting a primary amine with phosgene in the gas phase above the boiling point of the amine over an average contact time of 0.05 to 15 seconds under adiabatic conditions.

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&#xb0; C. to about 600&#xb0; C. and mixed and reacted in a tube reactor characterized in that a number n&#x2267;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.

Process for the manufacture of (poly-)isocyanates in the gas phase

Process for the preparation of toluylene diisocyanate, specific mixtures of toluylene diamine and water, and the use of toluylene diamine and water mixtures to prepare toluylene diisocyanate

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. The invention also relates to intermediate mixtures of toluylene diamine and water which have a solidification point of at most 95.degree. C., and the use of these intermediate mixtures for producing toluylene diisocyanate. It is preferable that the use of these intermediate mixtures to produce toluylene diisocyanate is performed at a site (or location) which is different from the site of production of the intermediate mixtures of toluylene diamine and water.

Process for the preparation of toluylene diisocyanate, specific mixtures

A process and a device are described for separating a solid residue, after separation, from a solution of the residue in evaporable materials and/or solvents with the addition of up to 20% by weight of high-boiling hydrocarbons that are inert under evaporation conditions of the evaporable materials, heating the mixture to evaporation temperature under vacuum, whereby the evaporable materials evaporate, are drawn off and condensed, and the residue is obtained as a free-flowing solid, the residue solution being introduced onto a stirred bed of granular solid material kept at the evaporation temperature.

Process and a device for separating a solid residue from its solution in

A continuous process for the preparation of aromatic diisocyanates by phosgenation of the corresponding diamines, in which the reaction is carried out in the gas phase. The mean contact time for the gaseous reactants is from 0.5 to 5 seconds with a mean deviation of no more than 6%. The product diisocyanate is obtained in yields of over 95%.

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Leverkusen, Germany

Klaus Biskup