Cyclopropyl-substituted spiro-photochromic compounds.

摘要

A fulgide or fulgimide compound having a cyclopropyl group as a substituent has excellent durability as a compound which changes reversibly in color from a colorless form to a colored form by the action of light containing ultraviolet rays such as sunlight or the light from a mercury lamp. There are also provided processes for its production, a composition comprising it, and its use in e.g. photochromic lenses.