Abstract: Twelve salicylaldehyde anils were synthesized and four of them are novel compounds. Their electronic spectra were determined in different solvents. The relationship between the first absorption band of enol’s and molecular structure were discussed. Blue shift of the first absorption band was caused by polar solvents, especially a protonic solvent. The first singlet excited state was a mixing state of ¹(n, π^*) and ¹(π, π^*) state. The influence of solvents on the tautomerism equilibrium of enol-quinonoid was discussed. The result demonstrated that protonic solvent was favourable to the formation of quinonoid.

Key words: photoisomerization, schiff base, tautomerism, absorption spectra