STILBENES,PROCESS FOR THE MANUFACTURE THEREOF AND THE USE THEREOF AS OPTICAL BRICHTENERS

摘要

Compounds of the formula I I in which X is O or S, R1 and R2, being identical or different, are radicals selected from the group of hydrogen, fluorine or chlorine atoms, phenyl, C1-C9-alkyl, C1-C4-alkoxy, C1-C4-dialkyl-amino, acylamino radicals, or optionally functionally modified carboxy or sulfo groups, two adjacent radicals R1 and R2 together optionally representing a benzo ring, a lower alkylene or a 1,3-dioxapropylene group, and A is a group of the formulae in which R3 and R4, independently from each other, are hydrogen, fluorine or chlorine atoms or C1-C4-alkyl groups.