Flash Photolysis Studies on Reactions Between Excited Molecules and Selected Substrates. Substituent Effects in the Cis-Trans Isomerization About the Carbon-Nitrogen Double Bond

摘要

Ethanol solutions of N-benzylideneaniline derivatives were photoisomerized and the kinetics for the thermal relaxation was measured. This thermal reaction follows first-order kinetics and the rate constants correlate with the Hammett sigma constants. The effect of a substituent is considerably stronger when it is attached to the aniline ring than when it occupies the corresponding position on the benzaldehyde ring. This is in agreement with the non-planar model for N-benzylideneaniline, where the pi-electron system of the aniline ring interacts with the lone-pair electrons of the nitrogen atom. (Author)