Synergistic Efficiency of 2-[(1-Aza-15-crown-5)-1-ylmethyl)]-4-(phenyldiazenyl)-naphthalen-1-ol in the Liquid Extraction of Light Lanthanoid(III) Ions with 4-Benzoyl-3-phenyl-5-isoxazolone: The Role of Aza-Crown and Azo-Dye Fragments on the Extraction Ability

Abstract

The solvent extraction of light lanthanoids with a mixture of 4-benzoyl-3-phenyl-5-isoxazolone (HPBI) and an azo-dye containing aza-crown in the side chain as a synergist (S), 2-[(1-aza-15-crown-5)-1-ylmethyl)]-4-(phenyldiazenyl)-naphthalen-1-ol (PDN1A15C5), was studied. To examine the role of the azo-dye on the extraction ability, its simplified analogue 1-benzyl-1-aza-15-crown-5 (BA15C5) was applied. The influence of the nitrogen on the crown fragment was estimated by a comparison with the efficiency of a series of crown ethers, benzo-15-crown-5 (B15C5) and 15-crown-5 (15C5). The lantaniod ions were extracted from perchlorate medium at constant ionic strength μ = 0.1 using CHCl 3 as an organic phase. The composition of the extracted species was established as Ln(PBI) 3 ·2S with PDN1A15C5 and BA15C5 and as Ln(PBI) 3 ·S in the presence of a crown ether. The values of the equilibrium constants were calculated. The influence of the synergistic agent on the extraction mechanism and enhancement is discussed. The parameters of the extraction processes were determined, and the separation factors between two adjacent lanthanoids were calculated.

Extraction Ability of 4-Benzoyl-3-phenyl-5-isoxazolone towards 4f-Ions into Ionic and Molecular Media

“…Atanassova et al have already demonstrated that the extraction of Ln ions using the strongly coordinating compound HPBI in a set of molecular diluents proceeds through a proton-exchange reaction, forming neutral tris complexes. [23][24][25][26][27] The extraction mechanism and the extraction constant of the neutral tris complexes (Kex,3) were represented by the following equations:…”

“…(11) from slope analysis (data not shown in the figures). [23][24][25][26][27] In addition, the values of log Kex,3 for La 3+ , Eu 3+ , and Lu 3+ in the chloroform system were determined to be -1.34 ± 0.10, 0.85 ± 0.11, and 0.73 ± 0.10 by a linear leastsquares fitting of the plots, respectively. Electroneutrality is an essential principle, as only neutral complexes may enter the hydrophobic molecular layer.…”

“…1,2-dichloroethane), including combinations with a wide variety of ligands, like crown ethers, 23 p-tert-butylcalix [4]arenes, 24,25 alkylammonium salts 26 including Aliquat 336 in its perchlorate form too. 27 Strong acidity due to the electron delocalization induced by the isoxazolone moiety makes 4-acyl-5-isoxazolones an interesting class of analogs to β-diketones with potential application at strong acidic media for developing a separation process for both lanthanoids and actinoids.…”

Complexation and Separation of Trivalent Actinides and Lanthanides by a Novel DGA Derived from Macrocyclic Crown Ether: Synthesis, Extraction, and Spectroscopic and Density Functional Theory Studies

“…For example, combined with 4-benzoyl-3-phenyl-5-isoxazolone (HPBI), the synergistic extraction D values of 15-crown-5 (15C5), benzo-15-crown-5 (B15C5, Figure S1 ), 1-benzyl-1-aza-15-crown-5 (BA15C5, Figure S1 ), and 2-[(1-aza-15-crown-5)-1-ylmethyl)]-4-(phenyldiazenyl)-naphthalen-1-ol (PDN1A15C5, Figure S1 ) for Eu(III) ions are 1.0, 0.5, 2.5, and 6.3 at pH 2.4, respectively. 29 Specifically, the La(III), Pr(III), and Eu(III) ions are extracted as Ln(PBI) 3 ·2S complexes (S = PDN1A15C5), while the light lanthanoid(III) ions of the 4f-series (La–Gd) form the extraction complex as Ln(PBI) 3 ·S species (S = B15C5 and 15C5). It should be noted that the addition of crown ether increases the extraction efficiency and the separation factors between the heavier Ln(III) and light Ln(III) are higher than those found for their extraction with the extractant alone.…”

“…To investigate the effects of macrocyclic crown ether compounds on the extraction and separation of trivalent lanthanides/actinides, some extractants and synergistic agents derived from crown ethers were developed. For example, combined with 4-benzoyl-3-phenyl-5-isoxazolone (HPBI), the synergistic extraction D values of 15-crown-5 (15C5), benzo-15-crown-5 (B15C5, Figure S1), 1-benzyl-1-aza-15-crown-5 (BA15C5, Figure S1), and 2-[(1-aza-15-crown-5)-1-ylmethyl)]-4-(phenyldiazenyl)-naphthalen-1-ol (PDN1A15C5, Figure S1) for Eu­(III) ions are 1.0, 0.5, 2.5, and 6.3 at pH 2.4, respectively . Specifically, the La­(III), Pr­(III), and Eu­(III) ions are extracted as Ln­(PBI) 3 ·2S complexes (S = PDN1A15C5), while the light lanthanoid­(III) ions of the 4f-series (La–Gd) form the extraction complex as Ln­(PBI) 3 ·S species (S = B15C5 and 15C5).…”