The staining properties of halo- and alkyl-thiazolylazophenol derivatives in histochemical staining of cadmium.

In the continuous research for a more sensitive chelator for cadmium, halothiazolylazodiethyaminophenol and alkylthiazolylazophenol derivatives were synthesized, and their staining sensitivity for cadmium chelates were examined with respect to a substituent group. 2-(4-Methyl- and 4,5-dimethyl-2-thiazolylazo)-5-diethylami-nonphenol showed low staining density in the 005-sections of cadmium, to date they showed the highest staining sensitivity for cadmium among the thiazolylazophenol analogs. The appropriate combination of substituent groups as based on their electron donative strength may be the decisive factor in determining the staining sensitivity of thiazolylazophenol analogs.