Condensation of 2(3)-amino- and 5-amino-2-hydroxybenzohydrazides with ketones and aldehydes

Condensation of 2(3)-amino- and 5-amino-2-hydroxybenzohydrazides with aldeh ydes involves primary amino groups of both aromatic and hydrazide moieties. The reaction with acetophenone occurs exclusively at the hydrazide fragmen t. Conformational equilibrium of the resulting Schiff bases is displaced to ward the (E,E ' ,E ") stereoisomer, the CH=N bond having E configuration. S chiff bases derived from salicylaldehyde exist as (E,E ' ,Z ") stereoisomer s stabilized by intramolecular hydrogen bond.