Inventors:
Barbara J. Wagner - Charleston SC
Bernd Kaletta - Leverkusen, DE
Assignee:
Miles Inc. - Pittsburgh PA
Bayer Aktiengesellschaft - Leverkusen
International Classification:
C07D20944, C07D23454
Abstract:
This invention relates to a process for preparing asymmetric isoindoline pigments of the formula ##STR1## in which R. sup. 1 is an electron-withdrawing group, R. sup. 2 and R. sup. 3 are independently hydrogen, alkyl, or aryl, and R. sup. 4, R. sup. 5, R. sup. 6, and R. sup. 7 are independently hydrogen, halogen, alkyl, alkoxy, or aryloxy. The process employs an initial reaction of a 1,2-dicyanobenzene with an alcohol in an organic medium in the presence of a base. The resultant imino-isoindoline intermediate composition reacts without isolation with a cyanomethylene compound NC--CH. sub. 2 --R. sup. 1 to form a partly condensed product that is then condensed without isolation in the presence of water with barbituric acid or a derivative thereof to form the asymmetric isoindoline pigment.