Dimerization of Ion-Pairs from Sodium Diphenyl Phosphate in Acetone at Various Temperatures
1996; Springer Nature; Volume: 12; Issue: 3 Linguagem: Inglês
10.2116/analsci.12.521
ISSN1348-2246
AutoresMasashi Hojo, Hiroshi Hasegawa, Yasuhiro Morimoto,
Tópico(s)Analytical chemistry methods development
ResumoConductometry, dimerization, ion pair, sodium Biphenyl phosphate, acetoneIt is well known that acetic and benzoic acids (HA) form dimers (H2A2) in very low permittivity solvents, such as benzene or chloroform.In high permittivity media, however, higher association (above the ion-pair) between uni-univalent electrolytes has been hardly believed to occur.In a series of studiesl, by means of polarography, spectrophotometry, and conductometry, we have demonstrated the formation of higher ion aggregates, e.g., triple ions (M2X+, MX2-) and quadrupoles (M2X2) from 1:1 electrolytes (MX) in relatively high permittivity media (20 <Er<65).The salt effects on acid-base reactions in acetonitrile were explained by the formation of triple ions and not merely ion-exchange reactions.2We have reported that the overall formation constants of (Li+)2(PhO)2PO2-(a triple cation or "reversecoordinated" species) and Li+((PhO)2PO2i2 (a triple anion or "coordinated" species) in acetone are log K2= ca.6.5 and 7. 1, respectively.3In the following study, we found that the interaction between Na+ and (PhO)2P02is smaller than that of Li+ in the same solvent.Large dimerization constants of diaryl and dialkyl phosphates, (RO)2P02H, in various (wet) organic solvents have been reported.4In the solvent extraction of metal ions with organophosphorus acids, it must be very important to identify the species present in organic phases as well as in aqueous phases.In the present study, sodium Biphenyl phosphate, Na+(PhO)2PO2-, in acetone (CF 20.7 at 25° C) was examined conductometrically at various temperatures (15, 25, and 35°C) to find the formation of the quadrupole (the dimer of ion-pairs) and to discuss the temperature dependence of the reactions in solution.The analysis of conductometric data was performed by the following equations.The ion pair formation of the salt (MX) is expressed by Eq. ( 1),
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