Estimation of Acid Dissociation Constants (pKa) of N-Containing Heterocycles in DMSO and Transferability of Gibbs Free Energy in Different Solvent Conditions

2020 ◽  
Vol 49 (3) ◽  
pp. 307-310
Author(s):  
Kowit Hengphasatporn ◽  
Toru Matsui ◽  
Yasuteru Shigeta
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Acid Dissociation Constants

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.

Sign in / Sign up

Export Citation Format

Share Document