Bayer Aktiengesellschaft

Konrad Hable

Alexander Klausener

Claus H Wulff

Siegfried Korte

Eberhard Zirngiebl

Gunther Weymans

Heinz Landscheidt

Erich Wolters

Jurgen Heuser

Zoltan Kricsfalussy

Reinhard Schomacker

Jurgen Kadelka

Karl-Heinz Feltgen

Rudiger Franck

Manfred Heckenbach

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

The invention relates to ultrafine suspensions of bisphenol, sodium hydroxide and water for the production of polycarbonates by the two-phase interfacial process. According to the invention, these suspensions are prepared by cooling bisphenolate concentrations near the solubility limit in aqueous sodium hydroxide with intensive mixing at relatively high temperatures and precipitating bisphenolate or more bisphenolate in the form of fine droplets during the cooling process. The ultrafine suspensions provide for a high volume/time yield in the interfacial reaction.

Production of ultrafine suspensions of bisphenol, sodium hydroxide and

This invention relates to a process for the radical homo-or copolymerization of acrylonitrile with one or more copolymerizable monomers under reaction conditions such that the monomers are present predominantly in a gaseous form of an adsorbed form and polymerization of the monomers, which are presumably adsorbed, takes place in the solid phase (solvent-free polymerization) and results in pulverulent PAN-(co)polymers. The process is preferably carried out in the presence of small quantities of a mediator substance such as dimethylformamide which does not alter the pulverulent consistency of the PAN-polymers but leads considerably more rapidly and with much improved yields to freshly formed polyacrylonitrile polymers.

Process for the solid phase polymerization of acrylonitrile from the

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Leverkusen, Germany

Konrad Hable