Synthesis, determination of pK(a) values and GIAO NMR calculations of some new 3-alkyl-4-(p-methoxybenzoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones

Yueksek H., Alkan M., Bahceci S., Cakmak I., Ocak Z., Baykara H., ...More

JOURNAL OF MOLECULAR STRUCTURE, vol.873, pp.142-148, 2008 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 873
  • Publication Date: 2008
  • Doi Number: 10.1016/j.molstruc.2007.03.016
  • Journal Name: JOURNAL OF MOLECULAR STRUCTURE
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.142-148
  • Karadeniz Technical University Affiliated: No

Abstract

3-Alkyl-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) reacted with p-methoxybenzoyl chloride to afford the corresponding 3-alkyl4-(p-methoxybenzoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3). Five newly synthesized compounds have been characterized by elemental analyses, IR, H-1 NMR, C-13 NMR and UV spectral data. The newly synthesized compounds 3 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents such as acetonitrile, isopropyl alcohol, tert-butyl alcohol and N,N-dimethylformamide, and the half-neutralization potential values and the corresponding pK(a) values were determined for all cases. Thus, the effects of solvents and molecular structure upon acidity were investigated. In addition, isotropic H-1 and C-13 nuclear magnetic shielding constants of compounds 3 were obtained by the gauge-including-atomic-orbital (GIAO) method at the B3LYP density functional level. The geometry of each compound has been optimized using the 6-311G basis set. Theoretical values were compared to the experimental data. (c) 2007 Elsevier B.V. All rights reserved.