A reaction of 4,6-di- tert -butyl-2,3-dihydroxybenzaldehyde with aliphatic (ethylenediamine, propylene-1,3-diamine, 1,4-diaminobutane) and aromatic ( o -, m- , p -phenylenediamines, 1,8-diaminonaphthalene, benzidine) diamines leads to the Schiff bases containing fragments of sterically hindered catechols in high yields (up to 97%). The products exist in two tautomeric forms in solutions and in the crystalline state. In the case of aliphatic diamines, catecholaldimines exist in solutions in the quinomethide form, whereas in the case of aromatic, in the catechol form. In the crystalline state, the position of the hydrogen atom in the O-H…N fragment is also affected by the intermolecular hydrogen bonds, which promote stabilization of the quinomethide form of catecholaldimines.