| abstract |
A chromogenic material of normally colorless form is disclosed, having a structural formula: WHEREIN R1 represents a radical having the structural formula NH-CO-Y or a radical having the structural formula -NH-SO2-Y wherein Y comprises phenyl, methoxyphenyl, naphthyl, quinolyl, benzyl, alkyl radicals having less than five carbon atoms, and amino-, nitro-, and alkyl-substituted phenyl radicals wherein the alkyl groups have less than five carbon atoms; R comprises hydrogen and alkyl radicals having less than five carbon atoms; and R2 comprises alkyl radicals having less than five carbon atoms. Examples include 2''-acetamido-6''-diethylaminofluoran; 6''diethylamino-2''-(phenylacetamido)fluoran; 6'' -diethylamino-2'' (p-toluenesulfonamido)fluoran; 2'' -acetamido-6'' -diethylamido-3'' -methylfluoran; 6'' -diethylamino-3'' -methyl-2'' -(ptoluenesulfonamido)fluoran; 6'' -diethylamino-2'' -(pnitrobenzenesulfonamido)fluoran; 6'' -diethylamino-3'' -methyl-2'' (p-nitrobenzenesulfonamido)fluoran; 6'' -diethylamino-2'' -(2naphthalenesulfonamido)fluoran; 6'' -diethylamido-2'' -(8quinolinesulfonamido)fluoran; and 6'' -diethylamino-2'' -(4methoxybenzenesulfonamido)fluoran. |