INTRAMOLECULAR PROTON TRANSFER EQUILIBRIUM IN SALICYLIDENE- AND NAPHTHALENE-BASED TETRAIMINE SCHIFF BASES

Abstract

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.

Keywords

• Tetraimines,Schiff bases; Tautomerism; Structure effect; Solvent effect

References

1. Aleksander Filarowski
2. Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie st., 50-383 Wrocław, Poland
3. Tel.: [phone]; fax: [phone]
4. [e-mail]
5. (Ortho-hydroxy aryl and heterocyclic Schiff bases, Tautomeric equilibrium, Intramolecular hydrogen bond)
6. Çiğdem Albayrak
7. Sinop University, Faculty of Arts and Sciences, Department of Chemistry, 57000 Sinop, Turkey
8. Tel.: [phone]; fax: [phone]

9. [e-mail]
10. (Proton tautomerism is experimentally and theoretically investigated.)
11. Halil Berber
12. Anadolu University, Faculty of Science, Chemistry Department, 26470 Eskişehir, Turkey
13. Tel.: [phone]x4827; fax: [phone].
14. [e-mail]
15. (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).