ISSN:
1572-8927
Schlagwort(e):
Stability constants
;
partial molal volume
;
isentropic partial molal compressibility
;
ionic partial molal compressibility
;
complex formation
;
crown ether
;
cations
;
water
;
hydration number
;
electrostriction
;
scaled particle theory
;
intrinsic volume
;
Drude-Nernst continuum model
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract The stability constants and the partial molal volume and isentropic partial molal compressibility changes of complex formation between cations and crown ethers in water at 25°C are presented. The cations involved are Na+, K+, Rb+, Cs+, Ca2+, and Ba2+, and the crown ethers are 12-crown-4, 15-crown-5, and 18-crown-6. Values of ΔV of complex formation have been discussed in terms of two simple models, one based on the scaled particle theory, and the others on the Drude-Nernst continuum model. The results indicate that the charge of the potassium cation in 18-crown-6 is especially well screened from the water. On this basis hydration numbers of complexed cations have been calculated. This shows that the size of the cation compared to the crown ether hole is important for the contacts between complexed cations and water.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00648577
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