Tautomerism of 4-hydrazinoquinazolines: vibrational spectra and computational study


  • Tetiana Yu. Sergeieva Oles Honchar Dnipropetrovsk National University, Ukraine
  • Olexiy Yu. Voskoboynik Zaporozhia state medical university, Ukraine
  • Sergiy I. Okovytyy Oles Honchar Dnipropetrovsk National University, Ukraine
  • Sergiy I. Kovalenko Zaporozhia state medical university, Ukraine
  • Jerzy Leszczynski Interdisciplinary center for Nanotoxicity, Jackson State University, United States




tautomer, 4-hydrazinoquinazolines, ab-initio, IR spectra, vibrational assignment


The tautomerism of 4-hydrazinoquinazoline and its derivatives was investigated. Geometry and thermodynamic parameters were computed theoretically using Gaussian 03 software. All calculations were performed at the MP2 level of theory using the standard 6-31G(d) basis. Energetics and relative stabilities of tautomers were compared and analyzed in a gas phase. The effect of solvents (1,4-dioxane, acetic acid, ethanol and water) on the tautomeric equlibria was evaluated using PCM. It was determined that solvents induced slight changes in the relative stability. In all cases 4-hydrazinoquinazoline exists predominantly as the amino form. The variation of dipole moments was studied. The anharmonic vibrational wavenumbers for unsubstituted 4-hydrazinoquinazoline were calculated at MP2/6-31G(d) level and compared with experimental data. The modes of IR spectra were assigned. The calculated herein wavenumbers and intensities of amino form are in good agreement with those observed experimentally.      

Author Biographies

Tetiana Yu. Sergeieva, Oles Honchar Dnipropetrovsk National University

Department of Organic Chemistry, PhD Student      

Olexiy Yu. Voskoboynik, Zaporozhia state medical university

Department of Organic Chemistry, Associate Professors      

Sergiy I. Okovytyy, Oles Honchar Dnipropetrovsk National University

Head of the Department of Organic Chemistry      

Sergiy I. Kovalenko, Zaporozhia state medical university

Head of the Department of Organic Chemistry      

Jerzy Leszczynski, Interdisciplinary center for Nanotoxicity, Jackson State University

Department of Chemistry and Biochemistry, Professor      


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