Related Experiment Video
Updated: Aug 8, 2026

Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
Self-consistent spectrophotometric basicity scale in acetonitrile covering the range between pyridine and DBU
1Institute of Chemical Physics, Department of Chemistry, University of Tartu, Jakobi 2, 51014 Tartu, Estonia, and Chemisches Laboratorium, Institut fur Organische Chemie und Biochemie, Universitat Freiburg, Albertstrasse 21, D-791.
Abstract:
A self-consistent spectrophotometric basicity scale in acetonitrile, including DBU, ten (arylimino)tris(1-pyrrolidinyl)phosphoranes, two (arylimino)tris(dimethylamino)phosphoranes, 2-phenyl-1,1,3, 3-tetramethylguanidine, 1-(2-tolyl)biguanide, benzylamine, two substituted benzimidazoles, pyridine, and ten substituted pyridines, has been created. The span of the scale is almost 12 pK(a) units. Altogether, 29 different bases were studied and 53 independent equilibrium constant measurements were carried out, each describing the relative basicity of two bases. The scale is anchored to the pK(a) value of pyridine of 12.33 that has been measured by Coetzee et al. Comparison of the basicity data of phenyliminophosphoranes and phenyltetramethylguanidines implies that the P=N bond in the (arylimino)tris(1-pyrrolidinyl)phosphoranes involves contribution from the ylidic (zwitterionic) structure analogous to that found in phosphorus ylides.
More Related Videos
14:11Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
11:38Quantifying the Binding Interactions Between Cu(II) and Peptide Residues in the Presence and Absence of Chromophores
Published on: April 5, 2022
Related Concept Videos
Titration Calculations: Weak Acid - Strong Base
For the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH, the reaction can be represented as:
Basicity of Heterocyclic Aromatic Amines
Titration of a Weak Base with a Strong Acid
Using the ICE table and substituting the Kb value, we calculate the initial pH of 50 mL of 0.1 M ammonia to be 11.11. Addition of 25 mL of 0.1 M hydrochloric acid to this solution of ammonia results in a buffer with an equal concentration of ammonia and ammonium ions. The pH of this buffer can be calculated by substituting these...
Titration of a Weak Acid with a Weak Base
As a result, there is no simple...
Titration of Polyprotic Base with a Strong Acid
Titration of Polyprotic Acids with a Strong Base