Diphasic acido-basic properties of D(octylphenyl)phosphoric acid (DOPPA)
- Laboratoire de Chimie Analytique, Paris (France)
- Centre de Developpement des Materiaux, Draria (Algeria)
In the first part of this work, the diphasic acido-basic constant (pka*) of di(octylphenyl)phosphoric acid, denoted hereafter DOPPA or HL, is determined from its experimental diphasic neutralization curve. The pka* value of DOPPA appears to be equal to 2.6 in the presence of 1 mol/dm{sup 3} sodium salt. Such a value is significantly lower than that previously determined for di(2-ethylhexyl) phosphoric acid (DEHPA, pka* = 5.2), 2-ethylhexylphosphonic acid, mono-2-ethylhexyl ester (PC88A, pka* = 7.1) and di(2,4,4-trimethylpentyl)phosphinic acid (CYANEX 272, pka* = 8.7). DOPPA (HL) is definitely more acidic than the other organophosphorus acids because its acidic proton can be easily exchanged with sodium cation to form Na{sup +}HL{sub 2}{sup -} species in organic phase. In the second and final part of the work, molecular modelling is used to model the dimers of various organophosphorus acids. A structure-activity relationship is obtained between the association energies of modelled dimers and their diphasic acido-basic constants. This relationship is then used for predicting the pka* values of DOPPOA and DOPPIA which are the phosphonic and phosphinic analogs of DOPPA, respectively. 16 refs., 5 figs., 4 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 70364
- Journal Information:
- Solvent Extraction and Ion Exchange, Vol. 13, Issue 4; Other Information: PBD: Jul 1995
- Country of Publication:
- United States
- Language:
- English
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