Bayer Aktiengesellschaft

Zoltan Kricsfalussy

Helmut Waldmann

Hans-Joachim Traenckner

Alexander Klausener

Heinz Landscheidt

Paul Wagner

Claus H Wulff

Wolfgang Alewelt

Gunther Weymans

Eberhard Zirngiebl

Hermann Kauth

Wolfram Wagner

Erich Wolters

Kaspar Hallenberger

Jurgen Heuser

Marko Zlokarnik

Harald Medem

Gunter Stammann

Reinhard Schomacker

Heinrich Steude

Joachim Schneider

Konrad Hable

C.sub.1 -C.sub.4 -Alkyl nitrites can be prepared by reaction of C.sub.1 -C.sub.4 -alkanols with nitrogen oxides with the participation of oxygen in a reactor designed as a scrubber column, nitrogen oxides having a proportion of more than 50% of NO of the total amount of gram atoms of N of the nitrogen oxides, oxygen and optionally inert gas being fed into the lower part of the reactor. 5 to 60% of the total amount of C.sub.1 -C.sub.4 -alkanol used is likewise fed into the lower part of the reactor in vaporous or atomized form, while the remaining C.sub.1 -C.sub.4 -alkanol is delivered to the column head.

Process for the preparation of C.sub.1 -C.sub.4 -alkyl nitrites

C.sub.1 -C.sub.4 -Dialkyl carbonates can be obtained from the corresponding C.sub.1 -C.sub.4 -alkanols, carbon monoxide and oxygen by reacting these substances in the presence of Cu salts, the water of reaction being limited to less than 10 wt % in the reaction mixture by at least partial withdrawal.

Process for the preparation of dialky carbonates

The preparation of dimethyl carbonate by reaction of methanol, carbon monoxide and oxygen in the presence of Cu compounds is carried out in distillation units and the water of reaction is removed at least partially from the stripping region or the bottom phase.

Process for preparing dimethyl carbonate

Organic compounds are selectively oxidized by means of a particularly advantageous process, using elemental oxygen and a catalyst containing palladium and copper and carrying out the process in the presence of carbon monoxide.

Catalytic oxidation

Dialkyl carbonates can be prepared by reacting carbon monoxide with alkyl nitrites in a continuous gas phase reaction in the presence of a heterogeneous platinum metal catalyst, the activity of this catalyst being maintained by the addition of small amounts of halogen. The dialkyl carbonates are thus formed with almost quantitative selectivity and no deactivation of the catalyst occurs.

Process for the preparation of dialkyl carbonates

An improvement to the continuous process for the production of polycarbonates by interphase polycondensation is described. Accordingly, the organic phase and the aqueous phase are combined in a tube, forming chlorocarbonic acid ester and further alkali hydroxide is added at, or shortly after, the maximum concentration of said ester is reached. The resulting emulsion is then changed to an oil-in-water emulsion which is then separated and worked up in known manner.

Continuous production of polycarbonates

To prepare C.sub.1 -C.sub.4 -dialkyl carbonates, C.sub.1 -C.sub.4 -alkanols are reacted with CO and O.sub.2 at a relatively high temperature in a salt melt containing Cu salts.

Catalysts for the gas-phase reduction of aromatic nitro compounds to aromatic amines are regenerated by treatment of the catalyst, at elevated temperature, with a gas mixture which contains oxygen, inorganic and/or organic amines and/or nitrogen oxides and, where appropiate, steam.

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Leverkusen, Germany

Zoltan Kricsfalussy