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, cilt.140, sa.4, ss.381-386, 2009 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 140 Sayı: 4
  • Basım Tarihi: 2009
  • Doi Numarası: 10.1007/s00706-008-0037-y
  • Dergi Adı: MONATSHEFTE FUR CHEMIE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.381-386
  • Gazi Üniversitesi Adresli: Evet

Özet

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.