ISSN:
1572-8927
Keywords:
Cations
;
complexation constants
;
conductivity
;
Hammett relations
;
ligands
;
nitrobenzene
;
ortho-dichlorobenzene
;
pyridines
;
triethylammonium picrate
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The dissociation constants Kd of triethylammonium picrate have been determined from conductimetric measurements in nitrobenzene (NB) and in ortho-dichlorobenzene (ODCB) with and without pyridines being used as ligands. In the absence of any ligand, the enhancement of the dissociation in NB as compared with that in ODCB cannot be explained solely by the increase of the dielectric constant, but shows the existence of specific interactions of the former solvent with the ions. The results obtained in the presence of ligands are consistent with the formation of a 1:1 cation-pyridine hydrogen-bonded complex. The constantk 1 + for the formation of theis complex has been determined for six substituted pyridines in both solvents. Logk 1 + varies linearly with the Hammett parameter σH of the substituent. The slope ρ of the Hammett relation is −1.86 in NB and −2.90 in ODCB. The difference can be ascribed to specific interactions between NB and the pyridines which become stronger when the pyridine is more basic.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00649877
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