Thermochromism and photochromism of aryl substituted acyclic azines : Uncatalised and acid-catalised thermal isomerisation

Abstract

The photochemical E- Z isomerisation of the benzophenone-9-anthraldehyde azine ( 1), benzophenone-9-acridine aldehyde azine ( 2) and 9-anthraldehyde azine ( 3) is thermally reversible. The thermal reaction gives the same isomers as the photochemical reaction. We have studied the mechanism of the thermal isomerisation of these azines. Our results are in accordance with an inversion of the N atom which is connected with a rotation movement about the N-N single or the CN double bond.