| 摘要 |
<p>In one embodiment, the present invention is concerned with novel xanthene compounds of the formula < IMG > wherein each R1 is the same and is selected from < IMG > R2 is alkyl, R3 is an electron-withdrawing group positioned ortho, meta or para to said N atom, R4 is hydrogen, alkyl or an electron-withdrawing group positioned ortho, meta or para to said N atom; R5 is alkyl; X is hydrogen, an electron-withdrawing group or an electron-donating group; and A is an anion. In another embodiment, the present invention is concerned with photographic products and processes employing these xanthene compounds, e.g., as photographic light-screening dyes.</p> |
