Bayer Aktiengesellschaft

Dietmar Mayer

Heinz U Blank

Horst Behre

Gunter Rauchschwalbe

Karl Mannes

Roland Busse

Herbert Emde

Erich Hammerschmidt

Friedrich Durholz

Dorde Jovcic

Eike Gabel

Wilfried Kohler

Horst-Dieter Kramer

Lothar Jakob

The characteristic of the improved process for the preparation of 1,5-dihydroxynaphthalene and 1,5-diaminonaphthalene is to carry out the alkaline pressure hydrolysis of the disodium salt of naphthalene-1,5-disulphonic acid at temperatures from 270.degree. to 290.degree. C. and under 14 to 20 bar using an excess of sodium hydroxide solution such that the molar ratio NaOH/disodium salt of naphthalenesulphonic acid is at least 12:1. The 1,5-dihydroxynaphthalene which is obtained in this manner, without hazard and in substantially higher purity, is then aminated with ammonia in the presence of ammonium bisulphite to give 1,5-diaminonaphthalene, it being possible to achieve a further increase in the degree of purity of the 1,5-diaminonaphthalene by increasing the molar ratio NH.sub.3 /1,5-dihydroxynaphthalene to at least 6:1.

Process for the preparation of 1,5-dihydroxynaphthalene and

Reactions of liquid starting substances to give chemical compounds in which these chemical compounds are obtained as solids can be carried out by spraying the liquid starting substances from separate nozzles such that the liquid starting substances are mixed in the spray cones, which penetrate one another, and thereby react.

Process for the preparation of chemical compounds obtained as solids

Solid crystalline tetra-alkali metal salts of chromotropic acid, a process for their isolation and their use for the preparation of pure chromotropic acid or di-alkali metal salts of chromotropic acid.

Tetra-alkali metal salts of chromotropic acid, a process for their

Hydroxydiphenyls can be prepared by reacting diphenylsulphonic acids or their alkali metal salts with an alkali metal hydroxide at elevated temperature and elevated pressure, in the presence of water. For this purpose, the diphenylsulphonic acids or their alkali metal salts are reacted, at a temperature between 280.degree. and 330.degree. C. and a pressure of up to 120 bar, with an amount of aqueous alkali metal hydroxide having a concentration of at least 50% by weight, such that, after all acidic groups have been neutralized, 3 to 25 mols of alkali metal hydroxide per equivalent of sulphonate group are present in the reaction mixture. Mineral acids are added to the alkaline reaction mixture, after it has been cooled and diluted with water, until the pH value is less than 8, and the precipitated hydroxydiphenyl is isolated at a temperature from -5.degree. C. to +100.degree. C.

Process for the preparation of alkali metal diphenylates and free

In a process for the preparation of an aromatic chloroformic acid ester by contacting a phenol and phosgene, the improvement wherein the reaction is carried out in a homogeneous liquid phase at a temperature of 60.degree. to 180.degree. C. in the presence of organic phosphorus compound of the formula

Process for the preparation of chloroformic acid aryl esters

In a process for the preparation of a naphthalenesulphonyl chloride by reacting an alkali metal salt or ammonium salt of a naphthalenesulphonic acid with thionyl chloride in the presence of a catalytically active substance the improvement wherein the reaction is carried out in the presence of an optionally substituted pyridine, tertiary aliphatic amine, secondary amidine and/or quaternary ammonium salt.

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Bergisch Gladbach, Germany

Dietmar Mayer