Bayer Aktiengesellschaft

Eckart Waldau

Gerhard Wegener

Herbert Stutz

Udo Birkenstock

Klaus Biskup

Herbert Gebauer

Christian Konig

Harro Witt

Peter Fuhrmann

Hans-Georg Frosch

Dieter Becher

Heinrich Grave

Hans Warlimont

Bodo Temme

Bernd Pennemann

Robert Bankwitz

Uta K&uuml;hn

Christian K Onig

Raney nickel catalysts, a method for producing said raney nickel catalysts and the use of the same for hydrogenating organic compounds

Organic isocyanates are continuously prepared by reacting primary organic amines with phosgene in the presence of an inert, organic solvent, with the reaction mixture being circulated by means of a bubble column at a temperature of from 60.degree. to 100.degree. C. and with the ratio of the quantity of the circulated amine reaction products to the quantity of the amine supplied of from 100:1 to 5:1.

Continuous process for the preparation of organic isocyanates

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%.

Process for the preparation of aromatic diisocyanates

The present invention relates to a process for the preparation of diisocyanates corresponding to the formula

Process for the preparation of (cyclo)aliphatic diisocyanates

Aromatic diamino compounds are produced by hydrogenating the corresponding dinitro compounds in the presence of a modified Raney catalyst. The modified Raney catalyst is obtained by treating an alloy made up of 50-95 wt % of aluminum, 4-45 wt % nickel and/or cobalt and 1-46 wt % of at least one modifying metal with an alkali material. The modifying metal is selected from the metals of the first, fourth, fifth, sixth, seventh and eighth subgroups of the Periodic Table of Elements. The hydrogenation is preferably carried out at from 170.degree. to 250.degree. C. and a pressure of 15-50 bar. The heat generated during hydrogenation is preferably used to produce steam.

Production of aromatic diamino compounds using a modified Raney catalyst

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Düsseldorf, Germany

Eckart Waldau