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2 Polish Journal of Chemistry

2 2008

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Solvent Extraction of Potassium by Nitrobenzene Solution of Sodium Dicarbollylcobaltate in the Presence of p-tert-Butylcalix[4]arene-tetrakis(N,N-diethylacetamide)

Makrlík E., Vaoura V., Budka J.

Polish Journal of Chemistry

2008

Vol. 82, nr 7

1485-1485

Experimental Evidence, Stability and Proposed Structure of Protonated Tetramethyl p-tert-Butylcalix[4]arene Tetraketone

Makrlík E., Dybal J., Budka J., Vaoura V.

Polish Journal of Chemistry

2008

Vol. 82, nr 7

1441-1441

From extraction experiments and gamma-activity measurements, the extraction constant corresponding to the equilibrium H3O+(aq) + 1×Na+(nb) 1.H3O+ (nb) + Na+(aq) taking place in the two-phase water–nitrobenzene system (1 = tetramethyl p-tert-butylcalix[4]arene tetraketone; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex(H3O+,1.Na+) = –0.6š0.1. Fur ther, the sta bil ity con stant of the 1×H3O+ complex in water saturated nitrobenzene corresponding to the equilibrium 1(nb) + H3O+(nb) 1×H3O+ (nb) was calculated for a temperature of 25°C as log beta nb (1×H3O+) = 9.7š0.2. Finally, by means of DFT cal cu la tions, three dif fer ent struc tures of this com plex spe cies were in di cated. The cal culated stabilization energy of 1×H3O+, –406.7 kJ mol–1, is the same for of all three optimized structures.