Beiträge zur Chemie der Pyrrolpigmente, 13. Mitt. Die thermische Stabilität der geometrischen Isomeren von Arylmethylidenpyrrolinonen

From kinetic studies and the investigation of several model compounds it has been deduced that the interconversion of (E)- and (Z)-arylmethylidenepyrrolinones proceeds via a thermal accessible dipolar (singlet) state thus being analogous to the many known thermal (Z)—(E)-isomerizations. There is a pronounced dependence of this reaction on the solvent and the substitution of the aryl part of the molecule; the equilibrium position between (Z)- and (E)-isomers is determined by the substituent in position 4 of the pyrrolinone ring.

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12. Mitt.:H. Falk undJ. M. Ribó, Mh. Chem.107, 307 (1976).