Hoechst Aktiengesellschaft

Hoechst Celanese Corporation

Sigri Great Lakes Carbon Gmbh

Siegbert Rittner

Helmold Von Plessen

Rudolf Steiner

Thomas Wisser

Jorg Schmid

Hans-Martin Ruffer

Bernhard Wojtech

Axel Konig

Adolf Schmidt

Herbert Kuckertz

Volker Hautzel

Hilmar Mildenberger

Heinz Strutz

Edward G Zey

Udo Gruber

Leonhard Unverdorben

Stephen Lachhein

Heinrich Volk

Donna L Keene

Helmut Schlaf

Rudolf Neeb

Heribert Tetzlaff

Manfred Mayer

Ernst Horoldt

Knut Riedel

Werner Wykypiel

Klaus Schmiedel

Eugen Morach

J Urgen Kulpe

Ulrich Girrbach

Gary L Moss

Larry O Wheeler

Edgar Wetzel

Rolf Bader

Hubert Schindler

Siegfried Bildstein

Richard Grimm

Jack Chosnek

Herbert Gortz

Von Helmold Plessen

Jurgen Spiske

Dieter Kompalik

Norbert Doerpinghaus

Karl Muck

Hans-Martin R Uffer

Peter John

Hartmut Last

Heinz Reiss

Reinhard Zunder

Josef Rosenfelder

Helmut Gossel

George E Beck

Wilfried Billmann

A process for the preparation of 2-hydroxynaphthalene-6-carboxylic acid using potassium carbonate and CO at temperatures above 260.degree. C. and at a pressure of at least 10 bar comprises using 2-hydroxynaphthalene-3-carboxylic acid and/or 2-hydroxynaphthalene-3,6-dicarboxylic acid and/or their potassium salts and, if desired, potassium .beta.-naphtholate as starting materials. The process according to the invention enables a considerable increase, by reusing the secondary products, in the product selectivity with regard to 2-hydroxy-naphthalene-6-carboxylic acid.

Process for the preparation of 2-hydroxynaphthalene-6-carboxylic acid

A process for the preparation of aromatic hydroxy carboxylic acids by reacting alkali metal phenolates or alkali metal naphtholates with alkali metal carbonates and carbon monoxide, with subsequent acidification, wherein the solid starting materials--alkali metal carbonate and/or alkali metal phenolate or naphtholate--are metered into the reaction mixture in the form of one or more dispersions in an inert organic liquid. The process according to the invention enables the preparation of aromatic hydroxy carboxylic acids in good yields and with high chemical selectivity. Additional measures for increasing the selectivity, as described for example for the Kolbe-Schmitt reaction in EP-A 0 053 824, EP-A 0 081 753 and EP-A 0 254 596, and for the reaction with CO and carbonate in, for example, WO 91/11422, are unnecessary.

Process for the preparation of aromatic hydroxy carboxylic acids

This invention embodies a process for releasing acidic organic compounds in high yield and good purity from aqueous solutions of their salts which comprises converting the salts by carbon dioxide to their corresponding free acidic organic compounds and metal hydrogen carbonates, removing the acidic organic compounds from the mixture by extraction with an essentially water-insoluble organic solvent, and re-extracting the organic phase with carbon dioxide containing water. Using this process, the acidic organic compounds are completely released from their corresponding salts, i.e., the organic solution is free of salt. The acidic organic compounds released by the claimed process are organic compounds which contain acidic protons which can be replaced by metals. Some examples are carboxylic acids, sulfonic acids, phosphonic acids, phenols, naphthols, and aliphatic alcohols.

Process for releasing acidic organic compounds from salts thereof by

A process for preparing aromatic hydroxycarboxylic acids or di-salts thereof by reaction of alkali metal phenolates or naphtholates with carbon dioxide, in the presence or absence of a further alkali metal salt, which comprises introducing the solid phenolate or naphtholate starting materials and, if desired, the alkali metal salt into the reaction mixture batchwise or continuously, separately or together, in the form of a dispersion in an inert organic liquid. The process of the invention makes possible the preparation of aromatic hydroxycarboxylic acids in good yields and with high chemical selectivity. Additional measures for increasing the selectivity, as are described for the Kolbe-Schmitt reaction in, for example, EP-A 0 053 824, EP-A 0 081 753 and EP-A 0 254 596, can be omitted.

Process for preparing aromatic hydroxycarboxylic acids

In the process for separating and purifying substances by crystallization from the melt under pressure, the melt is subjected to pressure under an inert gas atmosphere and then cooled, whereupon it crystallizes. The residual melt is separated from the resulting crystals, after which the crystals are degassed by reducing the pressure and are caused to sweat, and the sweat oil is separated off.

Process for separating and purifying substances by crystallization from

Process for separating and purifying substances by crystallization from the melt under high pressures In the process for separating or purifying substances by crystallization from melts or highly concentrated solutions under high pressures, gas is dissolved in the melt to be crystallized and is expelled again after the crystallization with reduction in the pressure. Still adhering or occluded impurities are thus removed.

The present invention relates to a process for purifying fatty acid amides, which contains the following process steps:

Process for purifying fatty acid amides

In the process for the preparation of pure trioxane by continuous or semicontinuous crystallization processes, if alkaline organic compounds are added no flocks appear after more than 120 hours of operation. As a result, blockage of the crystallization unit is prevented and problem-free running is made possible.

Process for the preparation of pure trioxane

Process for the preparation of 2-hydroxy-naphthalene-6-carboxylic acid

An ordered packing for mass transfer and heat exchange processes includes pre-formed individual parts. The packing is formed of carbon fiber-reinforced carbon with carbon fibers or carbon fiber yarns, which are linked one with the other by way of textile bindings, as a filler and of a matrix carbon, preferably based on synthetic resins.

Corrosion and heat-resistant ordered packing for mass transfer and heat

2-(4-Isobutylphenyl)-propionic acid is purified by subjecting it to a vacuum rectification, in which the temperature is below the decomposition temperature of the acid.

Process for purifying 2-(4-isobutylphenyl)-propionic acid by vacuum

A process for separating m- and p-dichlorobenzene by extractive rectification with an extractant and removal of this extractant. Using as extractant an alkylene carbonate of the formula ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are identical to or different from one another and each is hydrogen, methyl or ethyl, with the proviso that together the radicals R.sup.1 to R.sup.4 do not contain more than 6 carbon atoms. The process of the invention makes it possible to separate off the m-isomer in high purity.

Separation of m- and p-dichlorobenzene

The present invention relates to a process for the purification of 4-acetoxystyrene from a crude product mixture comprising 4-acetoxystyrene and typically 5 or more contaminants in substantial amount. The crude product mixture is purified by melt crystallization by cooling the mixture to a temperature ranging from about +8.degree. C. to about -50.degree. C., whereby at least a first portion of the mixture is crystallized; removing the liquid remaining from contact with the crystallized first portion of the mixture; and, subsequently slowly heating the crystallized first portion, while simultaneously removing liquid which forms due to the heating, whereby impurities contained in the liquid which forms are removed from the crystallized first portion. Surprisingly, despite the large number of contaminants present, and use of the process to purify crude product mixtures containing as little as 50% by weight 4-acetoxystyrene, purities as high as 99.9% by weight have been obtained using multiple melt-crystallization steps of the process of the invention.

Process for the purification of 4-acetoxystyrene

The invention relates to the dioxane adducts of armoatic meta-or para-hydroxycarboxylic acids, which consist, per mole, of 1 mole of 1,4-dioxane and about 2 moles of hydroxycarboxylic acid. The invention further relates to a process for the preparation of these adducts, which comprises dissolving the hydroxycarboxylic acids in dioxane or a mixture of the latter with water or with an organic solvent and then allowing the adducts to crystallize.

Dioxane adducts of aromatic meta- or para-hydroxy-carboxlic acids

The invention relates to the dioxane adduct of 2-hydroxynaphthalene-6-carboxylic acid which adduct comprises 1 mol of 1,4-dioxane and about 2 mol of 2-hydroxynaphthalene-6-carboxylic acid per mol. The invention further relates to a process for the preparation of this adduct, wherein the 2-hydroxynaphthalene-6-carboyxlic acid is dissolved in dioxane or a mixture thereof with water or with an organic solvent and then allowed to crystallize.

Process for the preparation of a dioxane adduct of

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Morfelden-Walldorf, Germany

Siegbert Rittner