4-(2-(6-Chloro-3-pyridazinyl)hydrazinylidene)valeric acid tert-butyl ester 5-25-17-00363 (Beilstein Handbook Reference) 69579-05-1 BRN 0924709 Pentanoic acid, 4-((6-chloro-3-pyridazinyl)hydrazono)-, 1,1-dimethylethyl ester Valeric acid, 4-(2-(6-chloro-3-pyridazinyl)hydrazinylidene)-, tert-butyl ester