Photochromic benzothioxanthone oxides, process for their preparation and the use thereof

Abstract

Compounds of formula I or III or mixtures thereof ##STR1## wherein R is unsubstituted C.sub.6 -C.sub.14 aryl or C.sub.6 -C.sub.14 aryl which is substituted by C.sub.1 -C.sub.12 alkyl, C.sub.1 -C.sub.12 alkoxy, C.sub.1 -C.sub.12 alkylthio, phenyl, benzyl, --CN, --CF.sub.3, halogen or --COOR.sub.3, x is 1 or 2, and R.sub.1 is H, linear or branched C.sub.1 -C.sub.12 alkyl, C.sub.2 -C.sub.12 alkenyl or C.sub.2 -C.sub.12 alkynyl, C.sub.7 -C.sub.16 aralkyl, C.sub.8 -C.sub.16 alkaralkyl, --CH.sub.2 COOR.sub.3 or C.sub.1 -C.sub.12 acyl, wherein R.sub.3 is H, C.sub.1 -C.sub.18 alkyl, cyclohexyl, cyclopentyl, phenyl, C.sub.1 -C.sub.12 alkylphenyl, benzyl or C.sub.1 -C.sub.12 alkylbenzyl, are reversible photochromic systems which can be used for contrast formation, light absorption or for the reversible optical storage of information.

Dependencies are inferred from the claim text.