Electrochemical behavior of some new pyrimidine derivatives


Kilic H., Berkem M.

JOURNAL OF THE SERBIAN CHEMICAL SOCIETY, cilt.69, ss.689-703, 2004 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 69
  • Basım Tarihi: 2004
  • Doi Numarası: 10.2298/jsc0409689k
  • Dergi Adı: JOURNAL OF THE SERBIAN CHEMICAL SOCIETY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.689-703
  • Marmara Üniversitesi Adresli: Evet

Özet

Electrochemical reduction of two recently synthesized pyrimidine compounds, 1-amino-5-benzoyil-4-phenyl-1H-pyrimidine-2-one (1), and 1-amino-S-benzoil-4-phenyl-1H-pyrimidine-2-thione (II) were investigated by cyclic volammmetry at a harming mercury drop electrode in aqueous methanol (36 v v) and in non-aqueous methanol. A series of cathodic peaks without the corresponding anodic peaks were observed for I. As the pH of the solution was increased, soiree of the cathodic peaks overlapped resulting in the loss of the previously observed peaks. For II. three cathodic peaks and one anodic peak were observed in addition to those observed for I. The peak potentials shifted in the negative direction with increasing pH. This shift was measured over a large pH range (1.80 - 12.30) to determine the pK(a) values of the compounds. The acidity constants related to the amino groups were 4.80 and 9.80 for I and 5.50 and 9.80 for II. A thiol-thione tautomerization was observed for II, which was more pronounced in the non-aqueous methanol medium. The pK values for both protonation and deprotonation of the thiocarbonyl group were also determined. The pK values were 5.80 and 9.80 for protonation and deprotonation in aqueous methanol and 6.80 and 10.80 in non-aqueous methanol.