Enichem Synthesis S.p.a

Nicola Casilli

Franco Rivetti

Fiorenzo Renzi

Luciana Crisci

A photochromatic composition contains at least two photochromatic compounds, defined by the general formula: ##STR1## wherein the various substituents from R.sub.1 to R.sub.7 and X are as defined in the specification. In such a mixture, at least one photochromatic compound is defined by the general formula, wherein R.sub.7 represents a hydrogen atom, and at least one further compound is also defined by the general formula, wherein R.sub.7 represents an -NR.sub.8 R.sub.9, with R.sub.8 and R.sub.9 having the meaning as defined in the text.

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Nicola Casilli