INTRAMOLECULAR PROTON TRANSFER EQUILIBRIUM IN SALICYLIDENE- AND NAPHTHALENE-BASED TETRAIMINE SCHIFF BASES
In this work, two nitro-Schiff bases were synthesized by condensation reaction of 4-nitro-benzaldehyde with p-phenylenediamine and 3-amino-2-naphthol in 2:1 and 1:1 ratios, respectively. Then, asymmetric tetraimine Schiff bases (L-1, L-2, L-3) were prepared by the reduction of nitro group to amino group with sodium dithionite and adding aldehyde, such as salicylaldehyde, 2-hydroxy-1-naphthaldehyde or terephthaldehyde. Tetraimines have been characterized by elemental analysis, FT-IR, 1H/13C NMR, UV–vis, and mass spectroscopy techniques in order to study the structure effect on the phenol-keto tautomerism. Solvent, acid and base effects on the tautomeric equilibrium have been also investigated by using UV–vis spectra.
Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie st., 50-383 Wrocław, Poland
Tel.: +48 71 3757229; fax: +48 71 3282348
(Ortho-hydroxy aryl and heterocyclic Schiff bases, Tautomeric equilibrium, Intramolecular hydrogen bond)
Sinop University, Faculty of Arts and Sciences, Department of Chemistry, 57000 Sinop, Turkey
Tel.: +90 368 2715532; fax: +90 368 2715530
(Proton tautomerism is experimentally and theoretically investigated.)
Anadolu University, Faculty of Science, Chemistry Department, 26470 Eskişehir, Turkey
Tel.: +90 222 335 05 80x4827; fax: +90 222 320 49 10.
(The tautomerisms of all of the Schiff bases compounds were determined in DMSO, CHCl3, C2H5OH and C6H12 solvents and in both acidic and basic media using the UV–vis spectrophotometric method).