The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 14, 1989
Filed:
Feb. 10, 1987
Helmut Herzog, Leverkusen, DE;
Detlef-Ingo Schutze, Cologne, DE;
Jurgen Schneider, Odenthal, DE;
Reinold Schmitz, Odenthal, DE;
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
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.