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Abstract

Photochromic compounds represented by the graphic formula: ##STR1## wherein: (a) R.sub.1 is selected from the group consisting of C.sub.1 -C.sub.8 alkyl, phenyl, phen(C.sub.1 -C.sub.4) alkyl, allyl and mono- and di-substituted phenyl, said substituents being selected from C.sub.1 -C.sub.4 alkyl and C.sub.1 -C.sub.5 alkoxy; (b) R.sub.2 and R.sub.3 are each selected from the group consisting of C.sub.1 -C.sub.5 alkyl, phenyl, C.sub.1 -C.sub.4 alkyl and C.sub.1 -C.sub.5 alkoxy mono- and disubstituted phenyl, benzyl or combined to form a cyclic ring selected from the group consisting of an alicyclic ring containing from 6 to 8 carbon atoms (including the spiro carbon atom), norbornyl and adamantyl, and (c) R.sub.4 and R.sub.5 are each selected from the group consisting of hydrogen, C.sub.1 -C.sub.5 alkyl, halogen, C.sub.1 -C.sub.5 alkoxy, nitro, cyano and C.sub.1 -C.sub.8 alkoxycarbonyl are described. Solvent systems which form photochromic compositions with the above compounds and articles containing the photochromic compound are described. The compound or compositions typically change from a colorless (nonexcited) or pale color, e.g., yellow, to blue after exposure to ultraviolet light.

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First Claim