Hoechst Aktiengesellschaft

Eberhard Ritter

Wilfried Sahm

Hartmut Heise

Hans Schafer

Claus-Peter Krieg

Martin Schottler

Bernd Leibmann

Dieter Morler

Thomas Vollheim

Detlev Keil

Process for the preparation of 2,5-di(phenylamino)terephthalic acid and dialkyl esters thereof in high purity. The invention relates to a process for the preparation of dialkyl 2,5-di(phenylamino)terephthalates of the formula (I) ##STR1## in which R is a hydrogen atom or a methyl group and R' is a methyl group or ethyl group, by dehydrogenation (oxidation) of the corresponding dialkyl 2,5-di(phenylamino)-3,6-dihydroterephthalate with oxygen, which comprises blanketing with oxygen a solution or suspension of the dialkyl 2,5-di(phenylamino)-3,6-dihydroterephthalate in aromatic hydrocarbons in a stirred vessel, circulating this reaction mixture via a spraying device, so that the sprayed reaction mixture is distributed over the reaction mixture present in the stirred vessel, the sprayed reaction mixture being mixed with the circulating gas. The process has the advantage of a short reaction time, combined with favorable space-time yields and simplicity in terms of apparatus.

Process for the preparation of 2,5-di(phenylamino)terephthalic acid and

A process for the preparation of 4-halo-3-oxo-2-alkoxyiminobutyric esters. A process for the preparation of 4-halo-3-oxo-2-alkoxyiminobutyric esters by solvent-free halogenation of the liquid substrate of a 3-oxo-2-alkoxyaiminobutyric ester with elemental halogen.

Process for the preparation of 4-halo-3-oxo-2-alkoxyaminobutyric esters

When continuously reacting an aqueous solution of 5-aminobenzimidazolone-(2) or a salt thereof with diketene then 5-acetoacetylamino-benzimidazolone is obtained in a smooth and safe reaction without foaming. The product results in high space-time yield and excellent quality.

Process for the manufacture of 5-acetoacetylamino-benzimidazolone

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Morfelden-Walldorf, Germany

Eberhard Ritter