Photochromic compound, process for production thereof, use thereof and composition containing said photochromic compound

A compound represented by the following formula [I] ##STR159## wherein ##STR160## represents a divalent benzene ring, a divalent naphthalene ring, a divalent 5-membered monoheterocyclic group having one hetero atom, or a fused heterocyclic group resulting from fusion of a benzene ring to said monoheterocyclic group, each of which may be substituted by at least one atom or group selected from the group consisting of halogen atoms, nitro groups, cyano groups, C.sub.1 -C.sub.4 alkyl groups, C.sub.1 C.sub.4 alkoxy groups, C.sub.1 -C.sub.4 alkylamino groups, di(C.sub.1 -C.sub.4)alkylamino groups, phenyl groups and C.sub.1 -C.sub.4 alkoxyphenyl groups, and when two alkyl groups are substituted on each said ring, they may be bonded to each other to form a ring,

• R.sub.1 represents a C.sub.1 -C.sub.6 alkyl group which may be substituted by a halogen atom or a C.sub.1 -C.sub.4 alkoxy group;
• a C.sub.7 -C.sub.10 aralkyl group may be substituted by a halogen atom;
• a C.sub.6 -C.sub.10 aryl group which may be substituted by a halogen atom, a nitro group or a C.sub.1 -C.sub.4 alkoxy group;
• ##STR161## represents a norbornylidene or adamantylidene group which may be substituted by at least one atom or group selected from the group consisting of hydroxyl groups, nitro groups, cyano groups, carboxyl groups, halogen atoms, C.sub.1 -C.sub.4 alkylamino groups, di(C.sub.1 -C.sub.4) alkylamino groups, C.sub.1 -C.sub.4 alkyl groups, C.sub.1 -C.sub.4 alkoxy groups, C.sub.1 -C.sub.2 haloalkyl groups, C.sub.2 -C.sub.10 alkoxycarbonyl groups, (C.sub.1 -C.sub.4)alkylcarbonyl(C.sub.1 -C.sub.4)alkyl groups, C.sub.7 -C.sub.15 aralkyl groups, C.sub.7 -C.sub.15 aralkoxy groups, C.sub.6 -C.sub.10 aryl groups and C.sub.6 -C.sub.10 aryloxy groups,
• X represents an oxygen atom or the group >N--R.sub.3 wherein R.sub.3 represents a C.sub.1 -C.sub.6 alkyl group, a C.sub.5 -C.sub.7 cycloalkyl group, a C.sub.7 -C.sub.10 aralkyl group or a C.sub.6 -C.sub.10 aryl group, each of which may be substituted by at least one atom or group selected from the group consisting of halogen atoms, cyano groups, nitro groups, hydroxyl groups, C.sub.1 -C.sub.5 alkoxy groups, C.sub.6 -C.sub.10 aryloxy groups, ##STR162## wherein R.sub.4 represents a C.sub.1 -C.sub.4 alkyl group or a C.sub.6 -C.sub.10 aryl group each of which may be substituted by a halogen atom, R.sub.5 represents a C.sub.1 -C.sub.4 alkyl group which may be substituted by a halogen atom or a nitro group, or a C.sub.6 -C.sub.10 aryl group or a C.sub.7 -C.sub.10 aralkyl group each of which may be substituted by a cyano group, and R.sub.6 and R.sub.7 are identical or different and each represents a hydrogen atom, a C.sub.1 -C.sub.4 alkyl group, a C.sub.7 -C.sub.10 aralkyl group or a C.sub.6 -C.sub.10 aryl group, and
• R.sub.2 represents a C.sub.1 -C.sub.6 alkyl group, a C.sub.5 -C.sub.7 cycloalkyl group, a (C.sub.5 -C.sub.7)cycloalkyl(C.sub.1 -C.sub.4)alkyl group or a C.sub.7 -C.sub.10 aralkyl group, each of which may be substituted by at least one atom or group selected from the group consisting of halogen atoms, cyano groups, nitro groups, hydroxyl groups, C.sub.1 -C.sub.6 alkoxy groups, C.sub.6 -C.sub.10 aryloxy groups optionally substituted by a halogen atom, C.sub.7 -C.sub.15 aralkoxy groups, ##STR163## wherein R.sub.4 represents a C.sub.1 -C.sub.4 alkyl group which may be substituted by a halogen atom, R.sub.5 represents a C.sub.1 -C.sub.4 alkyl group which may be substituted by a cyano group, and R.sub.6 and R.sub.7 are identical or different and each represents a hydrogen atom, a C.sub.1 -C.sub.4 alkyl group, a C.sub.7 -C.sub.10 aralkyl group or a C.sub.6 -C.sub.10 aryl group.