| 摘要 |
Use of N-substituted benzimidazoles of the formula Ia, where R1, R2, R3 and R4 are independently hydrogen, C1-4 alkyl, C1-4 alkoxy, halogen, cyano, carboxyl, (C1-4 alkoxy)carbonyl, -CONR6R7, -SO2NR6R7, -SO2R8, (C1-4 alkyl)carbonyloxy phenyl-, (C1-4 alkoxy)carbonyl-, cyano-, carboxyl- or CONR6R7-monosubstituted C1-4 alkoxy or R1 and R2 when adjacent to each other and/or R3 and R4 when adjacent to each other combine to form a fused-on benzene ring, R5 is phenyl or optionally hydroxyl-, cyano- , phenyl-, C2-4 alkenyl-, carboxyl-, (C1-4 alkoxy)carbonyl- or CONR6R7-monosubstituted C1-4 alkyl, R6 and R7 are independently hydrogen or C1-4 alkyl, R8 is C1-4 alkyl and X is O or S, subject to the proviso that at least one of R1 and R2 and not more than one of R3 and R4 represent cyano, carboxyl, (C1-4 alkoxy)carbonyl, -CONR6R7, -SO2NR6R7 or -SO2-R8, in the form of the free base, of an acid adduct or of the quaternary ammonium salt for optical brightening of substrates which are brightenable with cationic optical brighteners. Preference is given to using the monoprotonated and especially the monoquaternized compounds. <IMAGE> |
