Photochromic tetraphenyl naphthodipyrans

摘要

Described are novel reversible photochromic naphthopyran compounds which have two phenyl moieties adjacent to each oxygen of each pyran ring. The substituents on each pair of phenyl moieties mirror one another when the phenyl groups are substituted. The naphthodipyrans are prepared from beta , beta -dihydroxynaphthalene compounds.