Spectrophotometric determination of pK(a) values for some benzoic acid compounds in acetonitrile-water mixtures

PEKCAN G., Aktas A. H.

ASIAN JOURNAL OF CHEMISTRY, vol.18, no.3, pp.2168-2178, 2006 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 18 Issue: 3
  • Publication Date: 2006
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.2168-2178
  • Süleyman Demirel University Affiliated: Yes


The dissociation pK(a) values of benzoic acid and substituted benzoic acids have been determined in water and acetonitrile-water mixtures (10%, 20%, 30%) by spectrophotometric measurements. The results obtained show that the solvents affect the acid equilibrium. Acetonitrile acts as a strongly differentiating solvent with a modest solvating power for many polar ionic solutes. Linear relationships between pK(a) values in acetonitrile-water mixtures and pK(a) values in pure water have been established for fourteen benzoic acids. rhe pHab is a computer program using the calculation dissociation constants from spectrophotometric data obtained from solutions at known pH.