Basf Aktiengesellschaft

Wolfram Burst

Horst Hartmann

Wulf Kaiser

Kai-Uwe Baldenius

Harald Laas

Paul Grafen

Bernhard Bockstiegel

Andreas B&ouml;ttcher

Gerd Kaibel

Joachim Paust

Hansgeorg Ernst

Walter Dobler

Manfred Stroezel

Udo Rheude

Wolfgang Krause

Bernhard Schulz

Heinz Etzrodt

Walter-Wielant Wiersdorff

Harald Streicher

Peter Munster

Detlef Ruff

Ernst Schaffner

Guido Harms

Thomas Kuntze

Otto Worz

Arno Kochner

J&uuml;rgen Koppenh&ouml;fer

Josef Muller

J&uuml;rgen D&auml;uwel

Veronique Kessler

Armin Bertram

Gunter Dauwel

Heinz Dralle

Rolf Steinkamp

A dividing wall column is described which includes the following segments: a) an upper column region (), b) an enrichment section () of the feed section, c) a stripping section () of the feed section, d) an upper part () of the offtake section, e) a lower part () of the offtake section, f) an intermediate region () of the feed section, g) an intermediate region () of the offtake section and h) a lower column region (). The dividing wall column has a dividing wall () is located vertically between the segments b) () and d) () and between the segments c) () and e) (). The segments b) (), d) (), c) () and e) () have separation-active internals, Segment b () has a cross-sectional area Awhich is at least 10% smaller than the cross-sectional area Aof segment d) (), and segment c) has a cross-sectional area Awhich is at least 10% greater than the cross-sectional area Aof segment e) ().

Dividing wall column for fractionation of a multicomponent mixture

The invention relates to a process for the preparation of L-ascorbic acid, in which free 2-keto-L-gulonic acid or C -C -alkyl 2-keto-L-gulonate is lactonized under acidic conditions in the presence of a water-miscible solvent and where this solvent in situ forms a solvent in which the ascorbic acid formed is poorly soluble.

Method for the production of L-ascorbic acid by lactonization of 2-keto-L-gulonic acid or s2-keto-L-gulonate esters

C -C -alkyl 2-keto-L-gulonates are prepared by esterifying 2-keto-L-gulonic acid or diacetone-2-keto-L-gulonic acid with a C -C -alcohol in the presence of an acidic catalyst by a process in which the esterification is carried out in a liquid film on a hot surface with simultaneous removal of water.

Preparation of 2-keto-L-gulonic esters

A reflection column which contains liquid distributors having at least 500 drip points/m , which are arranged at an angle of about 90&deg; C. to cloth layers of packing elements located immediately therebelow; and a combination of insulation and protective heating. The column is advantageously used for the rectification of mixtures of high-boiling air- or temperature-sensitive substances requiring effective separation efficiency.

Rectification column for isolating pure substances from high boiling air-and/or temperature sensitive substances

Process for preparing high-purity phytantriol

Preparation of alkali metal salts of L-ascorbic acid

Process for isolation of pure substances from mixtures of high-boiling

A process for preparing 2,5,6-trimethyl-2-cyclohexen-1-one by reacting diethyl ketone with crotonaldehyde or a compound which is converted under the chosen reaction conditions into crotonaldehyde, in the presence of basic agents at elevated temperature, which comprises

Process for preparing 2,5,6-trimethyl-2-cyclohexen-1-one

Cloth or cloth-like packing which is subject to low pressure losses and

A process for preparing polyenecarbonyl compounds having a high all-E content and their acetals or ketals by aldol condensation or Horner-Emmons reaction comprises carrying out the reaction, for the purposes of the preferred formation of a double bond of E configuration and in order to maintain the E configuration of the double bonds in the stating compounds as completely as possible, in the presence of oxygen or an oxygen-inert gas mixture or nitric oxide or a nitric oxide-inert gas mixture and/or in the presence of specific stable radicals and/or in the presence of quinones or quinone derivatives.

Preparation of polyenecarbonyl compounds having a high content of the

Veratryl cyanide is prepared by chloromethylating veratrol in solution in toluene and then reacting the resulting veratryl chloride with from 1 to 5 moles of an alkali metal cyanide, by a process in which the toluene from the chloromethylation is not removed for the reaction with cyanide, and from 3 to 25% by weight, based on veratryl chloride, of water, from 5 to 50% by weight, based on toluene, of a ketone of 3 to 6 carbon atoms and from 0.1 to 10% by weight, based on veratryl chloride, of a phase transfer catalyst are added before the reaction with cyanide.

Preparation of veratryl cyanide

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Mannheim, Germany

Wolfram Burst