Bayer Aktiengesellschaft

Jurgen Schneider

Johannes-Rudolf Jansen

Detlef-Ingo Schutze

Reinold Schmitz

Martin Hoch

Helmut Herzog

Thomas Essert

Andreas Sattler

Helmut Dittmer

Hubert Schonhagen

Claus Krugermann

Catalyst system for the production of olefin (co)polymers

Process for the preparation of a 6,13-dihydroquinacridone of the general formula (I) ##STR1## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 designate hydrogen or substituents customary for quinacridone, characterized in that an optionally substituted dialkyl 2,5-di-(phenylamino)-3,6-dihydroterephthalate is heated to temperatures of 240.degree.-320.degree. C. in an essentially oxygen-free atmosphere in the presence of a dimethyl-diphenyl ether isomer mixture of the formula ##STR2## as the solvent and/or diluent, and a process for the preparation of optionally substituted quinacridone, characterized in that the resulting 6,13-dihydroquinacridone is oxidized in the customary manner.

Process for the preparation of 6,13-dihydroquinacridones and

1-Amino-2-bromo-4-hydroxyanthraquinone is obtained in good yields and in an environmentally acceptable manner by bromination of 1-aminoanthraquinone in 2 to 5 times the quantity by weight of 80 to 98% strength sulphuric acid and using 1.1-1.5 mole of bromine under elevated pressure.

Process for the preparation of 1-amino-2-bromo-4-hydroxyanthraquinone

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Odenthal, Germany

Jurgen Schneider