Medium and structural effects on the ionization constants of some pyrazole carboxylic acid derivatives

Alkan S., Zeybek B., Dogan A., KASIMOĞULLARI R., ERDOĞAN Y., KILIÇ E.

MONATSHEFTE FUR CHEMIE, vol.140, no.4, pp.381-386, 2009 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 140 Issue: 4
  • Publication Date: 2009
  • Doi Number: 10.1007/s00706-008-0037-y
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.381-386
  • Gazi University Affiliated: Yes


Stoichiometric ionization constants of some pyrazole carboxylic acids [4-benzoyl-1-(3-nitrophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid, 4-benzoyl-1(4-nitrophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid,4-(ethoxycarbonyl)-1,5-diphenyl-1H-pyrazole-3-carboxylic acid, 4-(ethoxycarbonyl)-1-(3-nitrophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid, 4-( ethoxycarbonyl)-1-(4- nitrophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid] were determined in ethanol-water mixtures of 50, 60, 70% ethanol (v/v) by a potentiometric titration method. Titrations were performed in an ionic strength of 0.10 M NaCl at 25.0 +/- 0.1 degrees C using an Orion 960 automatic titrator under a nitrogen atmosphere. Using the potentiometric titration data, ionization constants were calculated in three different ways. The effects of structure and solvent on the acidity of pyrazole carboxylic acids are also discussed.