Hoechst Aktiengesellschaft

Martin Schottler

Wolfgang Sievert

Hans Schafer

Eberhard Ritter

Heinz-Dieter Klein

Petra Meissner

Norbert Ochs

Thomas Vollheim

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

In a device for connecting apparatus for withdrawing ultrapure liquids from containers, the connection plate 4 is provided with three bores 5, 6, 7, of which two bores 5, 6 each extend through a socket 8 for vertical pipes. The top plate 9 has an integrated valve body 23 for accommodating at least two valve heads 2, 3 and three bores 10, 11, 12, which are congruent with the bores 5, 6, 7 of the connection plate 4. The bore 12 extends through the valve body 23, and the two other bores 10, 11 terminate, at one end thereof, in pipe sockets 29, 30, which project into the bores 5, 6 of the connection plate 4, and, at the other end thereof, in channels 31, 32, 33, 34 for the ultrapure liquids, which are arranged in the valve body 23 and are interrupted by the valve heads 2, 3.

Device for connecting apparatus withdrawing ultrapure liquids from

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Wiesbaden, Germany

Martin Schottler