| 摘要 |
Heterocyclic compounds of the formula <IMAGE> wherein R1 denotes hydrogen or C1-C4-alkyl, or the two R1s conjointly denote CO, R2 denotes a substituent and n denotes 0, 1, 2, 3 or 4 are suitable as coupling components for azo dyestuffs and especially for azo pigments of the formula <IMAGE> (V) wherein D denotes the radical of an aromatic or hetero-aromatic amine which is free from sulphonic acid groups and m denotes an integer, preferably 1 or 2, and R1, R2 and n have the abovementioned meaning.
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