prov:value
| - The arylene rings of the leuco dyes illustrated hereinabove can be further substituted, if desired, in the positions meta to the central methane carbon, with one or more (up to 2 each) lower alkyl (1 to 4 carbon atoms, substituted or unsubstituted), lower alkoxy (1 to 4 carbon atoms, substituted or unsubstituted, e.g. methoxy, ethoxy, etc.), halo (e.g. chloro, bromo, etc.), amino, or other groups
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