Interactions of metal extractant reagents. Part VIII. Comparative aggregation equilibria of Cyanex 302 and Cyanex 301 in heptane

Investigation of the State of Bis(2,4,4‐Trimethylpentyl)dithiophosphinic Acid in Nonane and Toluene Solutions

“…This contradicts the data from 746 N.A. Grigorieva et al other work that reported that the extractant is present mainly in the monomeric form when its total concentration is (0.1 M. [10,12,14] The vapor pressure osmometry (VPO) method was used to study the aggregation of unpurified Cyanex 301 in toluene (HR total 5 0.2-0.4 M) [7] and benzene (HR total 5 0.1 M), [15] and the method of small angle neutron scattering (SANS) was used to study the aggregation of purified Cyanex 301 in deuterated toluene (HR total 5 0.1 M). [16] All these experiments show that independent of the type of solvent (toluene, benzene, or deuterated toluene) and whether the extractant is purified or not, Cyanex 301 exists as a monomer in the organic phase across the studied extractant concentration range (up to 0.4 M in toluene).…”

“…[11][12][13][14][15][16] The use of vapor pressure osmometry to examine unpurified Cyanex 301/heptane solutions has revealed that the extractant is present in monomeric form in the concentration range of 0.016-0.16 M. [12] However, J. Chen et. al., [13] using an interfacial distribution method for the aqueous and organic phases, demonstrated that pure Cyanex 301 is dimeric in heptane solutions in the concentration range of 0.2-1.0 M (pH 5 3.66).…”

Influence of aggregation on the extraction of trivalent lanthanide and actinide cations by purified Cyanex 272, Cyanex 301, and Cyanex 302

“…As expected from the comparative weakness of the SH · · · hydrogen bond [10,11,31], the dimerization constant of the dithiophosphinic acid extractant, HC301, (K 2 = 0.67) is significantly smaller than those reported for the analogous oxygen-containing phosphinic acid (HC272, K 2 = 1.0 × 10 3 ) [32] and monothiophosphinic acid (HC302, K 2 = 20) [12] extractants. The results for HC301 can be compared to those reported for bis(2-ethylhexyl)dithiophosphoric acid (HDEHDTP) in deuterated cyclohexane [25], which can trimerize with K 3 = 0.14.…”

“…Although organodithiophosphinic acids are known to dimerize at high concentrations [10] or in the solid state [11], the bulk of the experimental evidence suggests that the monomeric form of the extractant predominates in organic solutions below at least 0.1 M [10,[12][13][14][15][16][17][18][19]. Recent neutron scattering experiments with Nd-HC301 complexes [20] support those finding and also indicate a 1 : 3 (Nd : HC301) stoichiometry for the extracted complex in toluene at low metal loading.…”

Aggregation equilibria of the components of the commercial extractants LIX 622 and LIX 622N in toluene and n-heptane

“…Several authors have studied the aggregation of metal extractant reagents by vapour pressure osmometry [8][9][10][11][12]. In recent works, small-angle neutron scattering (SANS) has been used in aggregation studies of metal extractants [13] and metal complexes [14].…”