Basf Aktiengesellschaft

Walter Bieg

Reinhold Kohlhaupt

Manfred Gaeng

Lothar Haas

Matthias Fankhaenel

Guenter Engelhardt

Toni Dockner

Peter Zehner

Regina Benfer

Stefan Birnbach

Jarren Peters

Werner Weinle

J&uuml;rgen Mohr

Ernst Lang

Bernd Ruge

A process for the continuous production of 1,3-dioxolan-2-ones such as ethylene carbonate or propylene carbonate by reacting a corresponding oxirane with carbon dioxide in the liquid phase in the presence of a catalyst comprises conducting the reaction in a two-part reactor in whose first part the reaction is taken with backmixing to a conversion of not less than 80% of the oxirane II and in whose second part the reaction is completed under nonbackmixing conditions, and passing the carbon dioxide in countercurrent to the oxirane II in the entire reactor.

Method for the continuous production of 1,3-dioxolan-2-ones

A process for purifying indigo comprises stripping the as-synthesized aqueous alkaline indoxylate solution before its oxidation to indigo of impurities in the absence of oxygen by distillation or by passing in steam or an inert gas and then treating the indigo precipitated on oxidation of the stripped indoxylate solution with dilute hydrogen peroxide solution.

Purification of indigo

A process for the preparation of purified indigo comprises extracting the aqueous alkaline indoxylate solution arising from the synthesis with an inert water-insoluble solvent in the absence of oxygen before oxidizing the indoxylate solution to give indigo.

Growing community of inventors

Gruenstadt, Germany

Walter Bieg