Observed n→π Bands in the Ultraviolet Absorption Solution Spectra of the Di-aza-naphthalenes

Abstract

Weak bands have been observed in the ultraviolet absorption solution spectra of phthalazine, quinoxaline, 6‐chloroquinoxaline, and 6‐bromoquinoxaline, which show ``blue‐shifts'' in a more polar solvent sequence. They, along with similar reported bands in cinnoline, have been assigned as n→π^* bands analogous to those of the diazines and triazines.