Synthesis and Photochromic Properties of Methyl Derivatives of Benzo[1, 2, 3-kl: 4, 5, 6-k′l′]dixanthene and Their Endope r o x i d e s t -Studies on Condensed Polycyclic Aromatic Compounds Having Photochromic Properties. II.-

Abstract

Methyl derivatives [3d] of benzo[1, 2, 3-kl: 4, 5, 6-k′l′]dixanthene [3a] were synthe; ized by the cyclization of 1, 5-diphenoxyanthraquinones, which were prepared from 1, 5-dichloroanthraquinone and potassium salt of cresol or xylenol. Electronic absorption spectra of [3b]-[3d] showed almost the same profile as that of [3a]. The photooxidation of the above red compounds[3b]-[3d] with visible light of 541 nm gave the colorless endoperoxides[4b]-[4d]. Tetramethyl derivative [3d], which is the most sterically hinder ed one among the compounds from [3a] to [3d] photooxidized about 1.5 times faster than [3a]-[3c]. Endoperoxide [4d] showed better thermal stability than those of [4a]-[4c].