Bayer Aktiengesellschaft

Dietrich Liebsch

Kuno Wagner

Otto Immel

Werner Kubitza

Peter Fischer

Jurgen Lahrs

Hans-Joachim Hennig

Heinz Sauer

Joachim Zirner

Winfried Dell

Stephan Wendel

Johannes Eimer

Rainer Raab

Hans-H Schwarz

Helmut F Porkert

This invention relates to a process for the preparation of an iron catalyst used for the hydrogenation of organic compounds comprising partially oxidizing iron or an iron alloy in particulate form at an elevated temperature in the presence of gaseous oxygen until a weight gain of from 5% to 32% is obtained; and then reducing the partially oxidized iron or iron alloy at an elevated temperature in a stream of hydrogen. The invention also relates to a process for the preparation of primary amines comprising catalytically hydrogenating nitriles corresponding to said primary amines in the presence of an iron catalyst of the invention.

Process for the preparation of an iron catalyst and a process for the

The present invention is directed to a process for the preparation of modified polyisocyanates containing uretdione and isocyanurate groups by the oligomerization of a portion of the isocyanate groups of organic diisocyanates containing (cyclo)aliphatically-bound isocyanate groups in the presence of organic phosphines of catalysts followed by termination of the oligomerization reaction at the desired degree of oligomerization by the addition of a catalyst poison and removal, by distillation, of at least a portion of the excess, unreacted starting diisocyanate, characterized in that

Process for the preparation of polyisocyanates containing uretdione and

Phosgene is produced by reacting chlorine and an excess of carbon monoxide in the presence of activated charcoal in a two stage process. In the first stage, the chlorine and carbon monoxide are reacted in a tubular reactor containing activated charcoal at a temperature above 250.degree. C. until 95 to 98% chlorine has reacted. The reaction gases are cooled to a temperature of from 50.degree. to 120.degree. C. and then introduced into a second reactor maintained at 50 to 100.degree. C. where the phosgene-forming reaction is completed. The phosgene leaving the second reactor has a residual chlorine content of less than 50 ppm. The heat generated during phosgene formation is used to produce steam.

Process for the production of phosgene with simultaneous generation of

Organic mono- or poly-isocyanates are produced on a continuous basis by phosgenating the corresponding amines. A solution of the amine to be phosgenated is continuously sprayed through a smooth-jet nozzle into a solution of phosgene continuously flowing through a mixing chamber. The mixing chamber is maintained at a temperature of 120.degree.to 300.degree. C. and a pressure of from 10 to 1000 bars. The molar ratio of phosgene to primary amino groups is generally from 2:1 to 30:1.

Continuous process for the production of organic isocyanates

Comparatively low viscosity biuret containing polyisocyanates are produced by reacting diisocyanates and biuretizing agents in proportions corresponding to a molar ratio of diisocyanate to monofunctional biuretizing agent of at least 11 : 1.

Process for the production of polyisocyanates with a biuret structure

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Leverkusen, Germany

Dietrich Liebsch