Isomere Diamino-alkoxy-pyridin-carbonitrile — ihre Trennung und Verwendung als Kupplungskomponenten

摘要

The isomeric 4,6-diamino-2-alkoxy- (3), and 2,4-diamino-6-alkoxy-3-pyridine-carbonitriles (4) are obtained by treatment of 2-amino-1,1,3-tricyanopropene (1) with sodium alkoxides. Separation is based on their differentpKa-values (3 a=2.01,4 a=4.17). Coupling reaction of3 a-cwith benzenediazonium chloride in strong acidic medium leads to the yellow azo dyes5 a-c, whereas coupling of4 arequires a buffered solution (pH4–6) to yield6. The UV-VIS spectra of the isomer pyridines and the azo dyes are discusse