scholarly journals Adding Explicit Solvent Molecules to Continuum Solvent Calculations for the Calculation of Aqueous Acid Dissociation Constants

2006 ◽  
Vol 110 (7) ◽  
pp. 2493-2499 ◽  
Author(s):  
Casey P. Kelly ◽  
Christopher J. Cramer ◽  
Donald G. Truhlar
Keyword(s):  
Dissociation Constants ◽  
Acid Dissociation ◽  
Acid Dissociation Constants ◽  
Aqueous Acid ◽  
Explicit Solvent ◽  
Solvent Molecules

Influence du substituant tertiobutyl-4 sur les constantes d'acidité du cation cyclohexylammonium et de l'acide cyclohexane carboxylique dans les milieux mixtes eau–DMSO et méthanol–DMSO

1976 ◽  
Vol 54 (12) ◽  
pp. 1899-1905 ◽  
Author(s):  
John T. Edward ◽  
Patrick G. Farrell ◽  
Jitka Kirchnerova ◽  
Jean-Claude Halle ◽  
Robert Schaal
Keyword(s):  
Dissociation Constants ◽  
Potentiometric Method ◽  
Acid Dissociation ◽  
Cyclohexane Ring ◽  
Acid Dissociation Constants ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Solvent Molecules

Acid dissociation constants for the compounds 1–6 in water–DMSO and methanol–DMSO of varying composition have been determined by a potentiometric method. In all solvents the equatorial group ionized more easily, by gain or loss of a proton, than the axial group, but in the more aqueous solvents the presence of a tert-butyl group across the cyclohexane ring inhibited this ionization slightly. An explanation based on displacement of solvent molecules from the outer solvation sphere is advanced.

The dissociation constants of ethylene diammonium and hexamethylene diammonium ions from 0° to 60° C

1952 ◽  
Vol 215 (1122) ◽  
pp. 416-429 ◽  
Keyword(s):  
Heat Capacity ◽  
Free Energy ◽  
Liquid Water ◽  
Dissociation Constants ◽  
Heat Content ◽  
Acid Dissociation ◽  
Ionic Charge ◽  
Acid Dissociation Constants ◽  
Heat Capacity Changes ◽  
Solvent Molecules

The two acid dissociation constants of the ethylene diammonium ion and the hexamethylene diammonium ion in water have been determined, using an e.m.f. method, from 0 to 60° C. Measurements have been made at several ionic strengths to allow thermodynamic dissociation constants to be derived, and from these the free energy, heat content, entropy and heat capacity changes accompanying the dissociations have been computed. These quantities are discussed in relation to the size of the diamine molecule, and orientation of solvent molecules by the ionic charges. It is concluded that the range over which a single ionic charge causes a significant change in the structure of liquid water is about 5 Å.

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