Related Experiment Video
Updated: Mar 1, 2026

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Proton dissociation properties of arylphosphonates: Determination of accurate Hammett equation parameters
Gergő Dargó1, Adrienn Bölcskei2, Alajos Grün2
1Compound Profiling Laboratory, Gedeon Richter Plc., Gyömrői út. 19-21., 1107, Budapest, Hungary; Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Műegyetem rakpart 3., 1111, Budapest, Hungary.
Abstract:
Determination of the proton dissociation constants of several arylphosphonic acid derivatives was carried out to investigate the accuracy of the Hammett equations available for this family of compounds. For the measurement of the pKa values modern, accurate methods, such as the differential potentiometric titration and NMR-pH titration were used. We found our results significantly different from the pKa values reported before (pKa1: MAE = 0.16 pKa2: MAE=0.59). Based on our recently measured pKa values, refined Hammett equations were determined that might be used for predicting highly accurate ionization constants of newly synthesized compounds (pKa1=1.70-0.894σ, pKa2=6.92-0.934σ).
Related Concept Videos
Basicity of Aliphatic Amines
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates higher...
Polyprotic Acids
Basicity of Heterocyclic Aromatic Amines
Titration of a Polyprotic Acid
¹H NMR: Complex Splitting
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Molecular Geometry and Dipole Moments

