Solubilities of dialkylhydrogen phosphonates in supercritical carbon dioxide and their correlation using semi-empirical equations

The solubilities of dibutylhydrogen phosphonate (DBHP) and dihexylhydrogen phosphonate (DHHP) in supercritical carbon dioxide were determined at 313-333 K and 10-20 MPa. The mole fraction solubility of DBHP and DHHP are in the range of 3.4 x 10(-4) to 66.4 x 10(-4) and 4.5 x 10(-4) to 806.6 x 10(-4,) respectively. The solubility data are self-consistent with Mendez-Teja model. The experimental solubilities were correlated using Chrastil, Hezave-Lashkarbolooki and three models based on activity coefficient models. Hezave-Lashkarbolooki model resulted in better solubility predictions for DBHP with an AARD of 5%. Chrastil and van Laar activity coefficient based model correlated the solubility of DHHP with a lowest AARD of 11%

Solubility of dialkylalkyl phosphonates in supercritical carbon dioxide: Experimental and modeling approach

Diallcylalkyl phosphonates have found renewed interest in the selective extraction of actinides from different matrices. In this context, two dialkylalkyl phosphonates, dibutylbutyl phosphonate (DBBP) and diamylamyl phosphonate (DAAP) were synthesised and their solubilities in supercritical carbon dioxide (SCCO2) medium were determined in the pressure range of 10-25 MPa at 313-333 K. Solubility studies were carried out to examine their utility as ligands during supercritical fluid extraction of actinides. Solubilities of dialkylalkyl phosphonates ranged from 0.06 to 0.12 mole fraction. Experimental solubilities were correlated using Mendez-Santiago, Chrastil, solution theory with Wilson activity coefficient model and association model based on van Laar activity coefficient model. Comparison among these models revealed that the association model with van Laar activity coefficient model provides better solubility predictions. SCCO2 containing DAAP was employed for the (i) selective extraction of uranium in the presence of simulated fission products and (ii) extraction of uranyl nitrate from acidic medium. (C) 2016 Elsevier B.V. All rights reserved

Unraveling the Conformational Landscape of Triallyl Phosphate: Matrix Isolation Infrared Spectroscopy and Density Functional Theory Computations

The conformations of triallyl phosphate (TAP) were studied using matrix isolation infrared spectroscopy and density functional theory (DFT) calculations. TAP was trapped in N₂, Ar, and Xe matrixes at 12 K using an effusive source and the resultant infrared spectra recorded. The computational analysis on conformers of TAP is a challenging problem due to the presence of the large number of conformations. To simplify this problem, conformational analysis was performed on prototypical molecules such as dimethyl allyl phosphate (DMAP) and diallyl methyl phosphate (DAMP), to systematically arrive at the conformations of TAP. The above methodology discerned 131 conformations for TAP, which were found to contribute to the room temperature population. The computations were performed using B3LYP/6-311++G­(d,p) level of theory. Vibrational wavenumber calculations were performed for the various conformers to assign the experimental infrared features of TAP, trapped in solid N₂, Ar, and Xe matrixes

Extraction and coordination behavior of diphenyl hydrogen phosphine oxide towards actinides

<p>Extraction behavior of some selected actinides like U(VI), Th(IV), and Am(III) was investigated with three different H-phosphine oxides, <i>viz.</i> diphenyl hydrogen phosphine oxide (DPhPO), dihexyl hydrogen phosphine oxide (DHePO) and diphenyl phosphite (DPP). The H-phosphine oxides exhibited a dual nature towards the extraction of actinides where the ligand not only extracts the metals by cation exchange but also by coordination with the phosphoryl group at lower and higher acidic concentrations, respectively. Among all ligands employed, DPhPO showed highest extraction with actinides with a substituent dependent trend as follows: DPhPO > DHePO > DPP. This trend emphasizes the importance of substituents around the phosphine oxide towards their extraction of actinides. The coordination behavior of DPhPO was studied by investigating its corresponding complexes with Th(NO₃)₄ and UO₂(NO₃)₂. The metal complexes of these actinides were characterized using FT-IR, ¹H and ³¹P NMR spectroscopic techniques. Density Functional Theory (DFT) calculations were also performed to understand the electronic and geometric structure of the ligand and the corresponding metal complexes.</p