On the condensation of salicylaldehyde with hydrazine

A simple procedure for preparing uncontaminated salicylaldehyde hydrazone is outlined. The condensation reaction of salicylaldehyde and hydrazine in 2:1 molar ratio usually gives initially a mixture of the three geometrical isomers of salicylaldazine: one isomer is bright yellow, another is cream, the third is light pink. The earlier reports of Feigl and of Terentev et al. on the use of salicylaldehyde in the detection of hydrazine have been found to be misleading and the later report of Jain et al. incomplete. A detailed account is now given and improved salicylaldehyde tests for hydrazine are recommended. The structure given by Jain et al. for the copper(II) complex of salicylaldehyde hydrazone is confirmed by means of infrared spectroscopy and microanalysis. Preliminary studies on the copper(II) complex of salicylaldazine are reported.