| 摘要 |
A chromogenic compound having the structural formula <IMAGE> +TR <IMAGE> wherein R1, R2, R3, R4 and R6 represent hydrogen, an alkyl group, a benzyl group or an aryl group; R5 represents hydrogen, an alkyl group, a benzyl group, an aryl group or Y, wherein Y represents <IMAGE> and R3' and R7 represent hydrogen, an alkyl group, a benzyl group or an aryl group; with the proviso that when R5 represents Y, R6 represents hydrogen and Y is at the 2 position, and n is an integer of 1 to 6. The aforesaid compound may be provided in a pressure-sensitive copy system wherein a visible image is formed upon reaction of the above chromogenic compound with an electron-accepting material of the Lewis acid type to produce a black image.
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