The shapes of the potentiometric acid-base titration curves obtained in the neutralizations of polyfunctional acids or bases for which each successive dissociation constant is smaller than the following one are examined. In the region 0 < < 1 (where is the fraction of the equivalent volume of reagent that has been added) the slope of the titration curve decreases as the number j of acidic or basic sites increases. The difference between the pH-values at = 0.75 and = 0.25 has (1 j)log 9 as the lower limit of its maximum value.
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http://dx.doi.org/10.1016/0039-9140(74)80033-0 | DOI Listing |
Anal Sci
January 2025
Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, Japan.
A digital-movie-based flow colorimetry for pH measurement using a universal indicator has been applied to the end point detection of acid-base titrations. A two-channel flow system of feedback-based flow ratiometry, primarily consisting of two peristaltic pumps, a digital microscope-based detector, and a laptop computer, was constructed; a Visual Basic.NET program written in-house was used for automating the analytical processes.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Ufa Institute of Chemistry, Ufa Federal Research Centre of the Russian Academy of Sciences, Laboratory of Physicochemical Methods of Analysis, 69 Prospekt Oktyabrya, Ufa 450054, Russian Federation.
The first-stage acid-base equilibrium of 5,5,6-trihydroxy-6-methyldihydropyrimidine-2,4(1,3)-dione was studied for the first time in aqueous solutions. Its constant (pK = 9.23 ± 0.
View Article and Find Full Text PDFCrit Care Explor
December 2024
Department of Anaesthesia and Intensive Care Medicine, The Third Faculty of Medicine, Charles University and FNKV University Hospital, Prague, Czech Republic.
Objectives: To evaluate the base excess response during acute in vivo carbon dioxide changes.
Design: Secondary analysis of individual participant data from experimental studies.
Setting: Three experimental studies investigating the effect of acute in vivo respiratory derangements on acid-base variables.
Int J Mol Sci
November 2024
Department of Pharmaceutical Chemistry, Semmelweis University, Hőgyes Endre utca 9, 1092 Budapest, Hungary.
The accurate determination of acid/base constants (proton dissociation constants-p, or equivalently protonation constants-log) is essential for the physicochemical characterization of new molecules, especially in drug design and development, as these parameters thoroughly influence the pharmacokinetics and pharmacodynamics of drug action. While pH/potentiometric titration remains the gold standard method for determining acid/base constants, spectroscopic techniques-particularly nuclear magnetic resonance spectroscopy (as NMR/pH titrations)-have emerged as powerful alternatives for specific challenges in analytical chemistry, providing also information on the structure and site of protonation. In this study, we performed a comprehensive meta-analysis of protonation constants reported in the literature, measured using both potentiometry and NMR titrations.
View Article and Find Full Text PDFACS Polym Au
December 2024
Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IET-2), Cauerstraße 1, 91058 Erlangen, Germany.
Polyethersulfone (PSU) as a commercially available polymer offers many different opportunities for functionalization for diverse fields of application, for example, electrophilic substitutions like sulfonation and bromination or nucleophilic reactions such as lithiation. This study presents three different polysulfone derivatives, first functionalized by a lithiation reaction, followed by a reaction with carbonyl compounds containing pentafluorophenyl groups. In the last step, the pentafluorophenyl moieties of the modified PSU were sulfonated by thiolation and subsequent oxidation to sulfonic acid groups.
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