Hoechst Aktiengesellschaft

Airbus Operations Gmbh

Axel Engelmann

Gunter Roscher

Heinz Litterer

Wolf-Dietmar Kaufmann

Bernd Laugwitz

Hans-Dietmar Schnabel

Heinz Hellwege

Gerd Hottendorf

Matthias Wilms

Process for the preparation of the non-toxic salts of

Process for the preparation of triphenylmethane dyestuffs of low electrolyte content, of the formula (A) ##STR1## wherein R.sub.1 and R.sub.2 each denote hydrogen, C.sub.1 -C.sub.4 -alkyl, benzyl or sulfobenzyl, R.sub.3 and R.sub.4 each denote hydrogen, C.sub.1 -C.sub.4 -alkyl or --SO.sub.3 H and R.sub.5 denotes a phenyl, chlorophenyl, dialkylaminophenyl, alkyldialkylaminophenyl, alkoxyphenylaminophenyl, sulfoanilido, sulfanilidophenyl, disulfobenzylaminophenyl, disulfophenyl, disulfohydroxyphenyl, sulfonaphthyl, disulfonaphthyl, hydroxydisulfonaphthyl or alkylphenylaminosulfonaphthyl group, the dyestuff molecule containing at least one sulfonic acid group, in the form of their ammonium or alkaline earth metal salts, by dissolving the corresponding leuco-compounds of the dyestuffs of the formula (A) with aqueous ammonia solution or mixtures of aqueous ammonia solution and alkali metal hydroxide solution, and then

Process for the preparation of acid dyestuffs of low electrolyte content

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Konigstein, Germany

Axel Engelmann