Photochromic naphthacenequinones, process for their preparation and the use thereof

A composition which comprises

• (a) a colorless substrate which is an organic solvent, a polymer, an organic glass or a compound glass;
• and
• (b) a compound of the formula V or a mixture thereof ##STR11## 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.5, and R.sub.5 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, and at least one of the substituents R.sub.1 to R.sub.4 is --F, --Cl or --Br, or is independently the group RO--, and the other substituents R.sub.1 to R.sub.4 are H, --F, --Cl or --Br;
• which compound of formula V is dissolved in the substrate, incorporated in the substrate, or present on at least one surface of the substrate.