Bayer Aktiengesellschaft

Gerhard Friedhofen

Volker Serini

Hans-Helmut Schwarz

Jurgen Heuser

Dieter Freitag

Rainer Neumann

Helmut Waldmann

Rudolf Braden

Otto Immel

Wilfried Niemeier

Gunther Jeromin

Christian Frohlich

Dieter Frietag

A process for the preparation of aniline by hydrogenation of nitrobenzene in the gas phase in the presence of a catalyst containing a noble metal is described. The process can be carried out in an improved manner if the catalyst employed is palladium on graphite or petrol coke, as the support, containing 0.001-1% by weight of Pd, based on the total weight of the catalyst, it being possible for the catalyst also to contain, in addition to the Pd, 0.001-0.5% by weight of Ir and/or 0.001-0.3% by weight of Rh, all figures being based on the total weight of the catalyst.

Catalyst for the preparation of aniline

This disclosure relates to the processes for producing polycarbonates from specific crude bisphenols. The bisphenols are characterized in that immediately after their preparation they are subjected to (i) separation, of excess phenols and low-boiling substances, by means of an evaporator, and (ii) removal of monophenols by desorption. The invention also relates to high-molecular weight aromatic polycarbonates made of crude bisphenols and their use in a variety of applications.

Preparation of polycarbonate from specific crude bisphenols

A process for the production of mixtures of alkylated aromatic polyhydroxy compounds by reacting alkylated phenols with carbonyl compounds, wherein acidic organic ion exchangers are used as catalysts and commercial dialkyl phenols as the phenol and any unreacted starting phenols separated off are completely recycled into the process without intermediate purification, and the application of the thus produced polyhydroxyl compounds for making thermoplastic polycarbonates.

Process for the production of mixtures of alkylated aromatic hydroxy

A process for the preparation of a 4,4'-dihydroxy-3,3',5,5'-tetraalkyl-diphenylalkane by reacting a 2,6-dialkyl phenol with a ketone in the presence of an acid organic ion exchanger wherein said acid ion exchanger is a macroporous resin with an average pore diameter of at least 300 A.

Process for the preparation of

The present invention is concerned with aromatic thermoplastic polycarbonates which contain at least about 0.5 mole % of structural units derived from 1,1,3,4,6-pentamethyl-3-(3,5 dimethyl-4-hydroxyphenyl)-indan-5-ol. The polymers disclosed herein may be homopolymers of these units or copolymers with other aromatic dihydroxy compounds and/or tri or higher functional branching agents. These homopolymers or copolymers may be used per se or they may be blended with other thermoplastic resins, particularly other aromatic polycarbonates. In addition, these polymers may be used to prepare coatings which may be cross-linked by heat treatment or radiation or they may be used as the base for graft polymerization.

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Krefeld, Germany

Gerhard Friedhofen