Micellar extraction of the lanthanide ions from acidic media

Article abstract of DOI:10.1007/s11172-009-0309-7

A procedure of micellar extraction of the lanthanide ions (La, Gd, and Lu) from nitric acid media based on the use of novel phosphine oxide derivatives is developed. In the micellar extraction, complexes of the lanthanide ions with the extractant in the ratio of 1: 2 (metal: extractant) form. The dependence of the selectivity of extraction on the length of hydrophobic radicals attached to the P=O group was shown. The conditions of the selective micellar extraction in the series La > Gd > Lu with the use of an extractant containing octyl substituents at the P=O group were found.

Full text of DOI:10.1007/s11172-009-0309-7

Russian Chemical Bulletin, International Edition, Vol. 58, No. 11, pp. 2222—2227, November, 2009
2222
Micellar extraction of the lanthanide ions from acidic media
Yu. G. Elistratova, A. R. Mustafina, D. A. Tatarinov, V. F. Mironov, and A. I. Konovalov
A. E. Arbuzov Institute of Organic and Physical Chemistry,
Kazan Research Center of the Russian Academy of Sciences,
8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation.
Fax: +7 (843) 273 2253. Eꢀmail: yulenka@iopc.kcn.ru
A procedure of micellar extraction of the lanthanide ions (La, Gd, and Lu) from nitric acid
media based on the use of novel phosphine oxide derivatives is developed. In the micellar extraction,
complexes of the lanthanide ions with the extractant in the ratio of 1 : 2 (metal : extractant)
form. The dependence of the selectivity of extraction on the length of hydrophobic radicals
attached to the P=O group was shown. The conditions of the selective micellar extraction in
the series La > Gd > Lu with the use of an extractant containing octyl substituents at the P=O
group were found.
Key words: micelles, pseudophase separation, lanthanide ions, phosphine oxides, extraction.
The problem of radioactive wastes disposal, as well as
terization and emergence of a micellar or coacervate
phase.9—11 It should be noted that its volume is very small
and consists of surfactant along with small amount of
the solvent. Another pseudophase is the solvent where the
surfactant content does not exceed critical micelle conꢀ
centration (CMC).13 The phenomenon of temperatureꢀ
induced phase separation, called the separation at the
cloud point (CP) and being the specific feature of soluꢀ
tions of nonionic and zwitterionic surfactants14 has found
the widest application in the separation processes.
the problem of waste water and waste soil monitoring at
their burial places is still topical. The method of extractive
concentration with the use of monodentate organoꢀ
phosphorus compounds (phosphates, phosphonates, and
phosphine oxides) as the extractants has found the widest
practical application in the radioactive waste processꢀ
ing.1—7 Phosphine oxide derivatives,4—7 including phosꢀ
phomethylated calixarenes,8 are the most efficient extractꢀ
ants of the series and can extract the cations of 4fꢀ and
5fꢀelements from the strong acidic media.
The procedure of extraction at the CP is environꢀ
mentally safe, as it requires no environmentally hazardous
or explosiveꢀsuspect organic solvents. The second imporꢀ
tant advantage of this extraction method is the possibility
of no less than 50ꢀfold concentration of the metal ions.9
The use of aqueous solutions of nonionic surfactants
for the extraction of the metal ions by temperatureꢀ
induced phase separation is limited by their low affinity to
the micellar phase. For enhancement of the extraction
effectiveness; the soꢀcalled chelating agents are used,
which form complexes with the metal ions thereby inꢀ
creasing their hydrophobicity and affinity to the micellar
phase. In addition to binding ability to the metal ion, the
chelating agent should be well soluble in the aqueous
solutions of nonionic surfactants. Oxyquinoline and its
derivatives found the widest application as chelating
agents for micellar extraction of the lanthanide ions.15,16
2ꢀ(3,5ꢀDichloroꢀ2ꢀpyridylazo)ꢀ5ꢀdimethylaminophenol
was also used as a chelating agent.17 The extraction proceꢀ
dure of UIV at the CP in the form of its complex with
Pyrocatechol Violet was developed18 on the basis of mixed
micellar solutions of Triton X100 (TXꢀ100) and CTAB.
The extraction is a mass transfer process from one
phase to another immiscible with the former. There are
various methods for the metal ion extraction and concenꢀ
tration. The method of liquid extraction has found the
widest practical application due to the reversibility of
the extraction process on the liquid—liquid interface and
rapid equilibration.1—3 However, the use of large volumes
of organic solvents is necessary for efficient liquid extracꢀ
tion, which makes this process environmentally unsafe
and leads to the necessity of additional metal concentraꢀ
tion in the organic phase.
The method of micellar extraction is being currently
rapidly developed, it is free from the aboveꢀmentioned
drawbacks.9—11 This method is based on pseudophase sepaꢀ
ration of aqueous and micellar phases. This separation
can be achieved by increasing temperature,11 varying the
acidity9 or ion strength12 of micellar solutions. The variaꢀ
tion of physical conditions, e.g., heating of a micellar
solution, reduces hydration of oxyethyl chains of surfacꢀ
tants. As a result, the spherical micelles reorganize into
cylindrical ones, which results in its subsequent clusꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2156—2161, November, 2009.
1066ꢀ5285/09/5811ꢀ2222 © 2009 Springer Science+Business Media, Inc.

Micellar extraction of lanthanides
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 11, November, 2009 2223
Scheme 1
A method of extraction of lanthanides with micellar soluꢀ
tions of TXꢀ100 and calix[4]resorcinarenephosphonic acid
as a chelating agent is known.19 However, the efficient
extraction of lanthanides with aboveꢀmentioned chelating
agents occurs only in neutral or weakly basic media; the
extraction efficacy substantially decreases with an increase
in acidity of aqueous solutions.15—19 It is caused by protoꢀ
nation of both the extractants and oxyethyl chains of surꢀ
factants.
Therefore, the search for novel chelating agents for
the extraction of lanthanides from acidic and stongly acidic
media by environmentally safe extraction at the CP is a
topical problem. Taking into account the aboveꢀmenꢀ
tioned extraction ability of phosphine oxide derivatives in
liquid extraction, a comparison of the effectiveness of
micellar and liquid extraction with novel phosphine oxide
derivatives as the extractants is of interest.
Comꢀ
pound
1
2
3
R1
R2
Comꢀ
pound
4
5
6
R1
R2
Me
Et
Bun
Ph
Ph
Ph
nꢀC6H13 Ph
nꢀC8H17 Ph
Ph
Bun
Results and Discussion
aqueous phase and constant concentration (0.2 mmol L–1)
of phosphine oxides 1—6 in the micellar solutions are
presented in Table 1. The results of liquid extraction
for the same concentration of extractants 3—6 (the conꢀ
centration of phosphine oxides in the liquid phase is
0.2 mmol L–1), are given in Table 2.
The analysis of these data makes it possible to reveal
the noticeable increase in the degree of extraction with
the increase in acidity of the aqueous phase (liquid
extraction) and micellar solution (micellar extraction).
It should be noted that the degree of extraction from the
Phosphine oxides 1—6 were synthesized by the reacꢀ
tion of chlorophosphorinine oxides 7 with the Grignard
reagent (RMgX, X = Br, I) followed by quenching of the
reaction mixture with water or aqueous hydrochloric acid
(Scheme 1). Chlorophosphorinine oxides 7 are accessible
compounds, which can easily be synthesized from phosꢀ
phorus pentachloride, pyrocatechol, and phenylꢀ or
butylacetylene (the methods of their synthesis have been
described earlier).20—22
The results of micellar extraction of the lanthanum,
gadolinium, and lutetium ions at variable acidity of the
Table 1. The degree of micellar extraction (Е (%)) of lanthanides in the systems TXꢀ100—extractant (1—6)—LnIII
at various pH (pH = 1 corresponds to 0.1 M HNO3)
Extractꢀ
ant
La
Gd
Lu
рН = 1
рН = 2
рН = 3
рН = 1
рН = 2
рН = 3
рН = 1
рН = 2
рН = 3
1
2
3
4
5
6
60
71
71
100
86
82
22
5
17
24
15
13
11
5
5
15
5
5
51
54
40
96
52
59
17
14
5
15
5
14
5
5
16
5
5
39
65
26
68
21
58
31
5
5
25
5
25
24
5
5
26
22
28
5
Table 2. The degree of liquid extraction (Е (%)) of lanthanides in the systems extractant (3—6)—LnIII at various
pH (pH = 1 corresponds to 0.1 M HNO3)
Extractꢀ
ant
La
Gd
Lu
рН = 1
рН = 2
рН = 3
рН = 1
рН = 2
рН = 3
рН = 1
рН = 2
рН = 3
3
4
5
6
71
100
86
17
24
15
13
5
15
5
57
91
42
60
5
20
5
5
5
5
5
36
54
34
38
5
10
5
5
23
5
82
5
5
16
15

2224
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 11, November, 2009
Elistratova et al.
aqueous phase are the same within the limits of the error
for both procedures. The maximum degree of extraction
is observed with phosphine oxide 4 used as the extractant.
It is known that electronꢀdonor character of the P=O
group exerts big influence on the extraction ability of
phosphine oxides.7 The results obtained in the present
study (see Tables 1 and 2) suggest the dependence of the
degree of micellar and liquid extraction on the nature of
the hydrocarbon radical R1. However, the correlation of
the degree of extraction with the length of the hydrocarꢀ
bon radical R1 is observed not for all of the lanthanide
ions. Particularly, the noticeable decrease in the degree of
micellar extraction of the gadolinium and lutetium ions is
observed on going from extractant 2 to 3. Taking into
account the multifactor nature of the extraction process,
the correct explanation of the observed regularity cannot
be made on the basis of the results obtained. The nature of
the radical R2 does not have considerable influence on
the efficiency and selectivity of the extraction in the series
lanthanum—gadolinium—lutetium, because it does not
affect directly the electronꢀdonor character of the P=O
group. Regardless of pH and the structure of the extractꢀ
ant used the lanthanum ion is extracted preferably. The
most efficient extractant 4 is inferior to extractant 5 in
selectivity, extraction of gadolinium and lanthanum beꢀ
ing nearly the same and the degree of extraction of the
lutetium ion being somewhat smaller. Extractant 5 is the
most selective and at the same time it retains its efficiency
toward the lanthanum ion. For example, the degree of
micellar extraction of the LaIII ion is ∼1.6 and ∼4.1 times
higher than of GdIII and LuIII, respectively. The highest
selectivity of extractant 5 in the series of extractants 1—6
can be explained on assumption that two octyl radicals
produce much greater steric strain in the coordination
sphere of the lutetium ion than in the coordination sphere
of the gadolinium and lanthanum ions. It should be noted
that the efficiency and the selectivity of the liquid and
micellar extraction with extractants 3—6 are similar.
The results of quantitative analysis of the concentraꢀ
tion dependence of the degree of micellar extraction of
the GdIII ions with extractants 3 and 5 at pH 1 are shown
in Figure 1 in the coordinate system logq—log[L] (q is the
extraction coefficient, q = E/(100 – E)). The increase in
the degree of extraction is observed only in the region of
0—0.2 mmol L–1 and it is caused by the formation of a
complex with the composition 1 : 2 (Gd : extractant). The
subsequent increase in the extractant concentration
almost does not influence on the degree of extraction.
The observed regularity can be explained by aggregation
of compounds 3 and 5 in the micellar pseudophase.
Taking into account the structures of extractants 1—6,
it is natural to assume the possibility of their bidentate
coordination with participation of the hydroxyl group in
coordination. The stoichiometry of GdIII complex with
ligands 3 and 5 (1 : 2) confirms this assumption, since
monodentate phosphine oxides form complexes with the
lanthanide ions with the composition 1 : 3. The extracꢀ
tion constants calculated on the base of the results
obtained are logKex(3) = 5.23 0.04 and logKex(5) = 6.11 0.01,
respectively.
logq
–0.2
–0.4
–0.6
a
–0.8
–1.0
–1.2
–1.4
–1.6
Thus, we developed for the first time a procedure of
micellar extraction of the lanthanide ions from nitric acid
media using novel phosphine oxide derivatives. The
dependence of selectivity of extraction on the length of
the hydrophobic radical at the P=O group was found. The
conditions for selective micellar extraction in the series
La > Gd > Lu at concentration of nitric acid 0.1 mol L–1
were established. It was shown that the stoichiometry
of the complexes formed 1 : 2 (metal : extractant) is not
typical of monodentate phosphine oxides due to bulkiness
of hydrophobic radicals at the donor groups and suggests
the possibility of bidentate coordination involving the
hydroxyl group.
–4.2 –4.0 –3.8 –3.6 –3.4 –3.2 –3.0 –2.8
log[L]3
logq
0.0
–0.1
–0.2
–0.3
–0.4
–0.5
b
Experimental
–4.2 –4.0 –3.8 –3.6 –3.4 –3.2 –3.0 –2.8
log[L]5
Fig. 1. The dependence of logq on log[L]3 in the system GdIII
—
NMR 31P—{1H} spectra were recorded on a Bruker
CPXꢀ100 instrument (36.48 MHz, 31P) in DMSOꢀd6 (35 °C)
in the δ scale relative to H3PO4 (85%) as the external standard.
IR spectra were obtained for Nujol mulls or KBr pellets on a
TXꢀ100—3 (a) and log[L]5 in the system GdIII—TXꢀ100—5 (b);
[GdIII] = 1.7•10–4 mol L–1, [TXꢀ100] = 2•10–2 mol L–1
(tgα = 2 on the linear region).

Micellar extraction of lanthanides
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 11, November, 2009 2225
FTIR Vectorꢀ22 spectrometer (Bruker). Mass spectra were
registered on a TRACE MS Finnigan MAT instrument with
ionization energy of 70 eV and the temperature of the ion source
200 °C. Heating of the injection ampoule was performed in a
temperature programmable regime from 35 to 150 °C with a
35 grad min–1 step. The mass spectra was processed with the use
of an Xcalibur program.
Oxyethylated isooctylphenol (Triton X100) (ICN Biomediꢀ
cals) was used, the mean number of the oxyethyl units is 10.
Lanthanum(III), gadolinium(III), and terbium(III) nitrates
(99.9%, Alfa Aesar) were used. The concentration of LnIII in the
stock solution was determined by titration with Trilon B with
Thymol Blue and Xylenol Orange as indicators.23
94%) in the form of brownish powder with m.p. 75—77 °C was
obtained. Found (%): C, 64.32; H, 6.12; Cl, 10.41; P, 9.41.
C18H20ClO2P. Calculated (%): C, 64.58; H, 6.02; Cl, 10.59;
P, 9.25. MS, m/z: 334 [M]+•, 305 [M – Et], 299 [M – Cl], 289
[M – Et – CH4], 275 [M – 2 Et – H], 259 [M – 2 Et – OH],
241 [M – 2 Et – Cl], 230 [C14H11ClO], 229 [C14H10ClO], 228
[C14H9ClO], 223, 215, 202, 194, 176,166, 165, 152, 139, 125,
111, 105 [C14H10OP], 78, 63, 53, 49, 43, 29. IR, ν/cm–1: 450,
505, 532, 583, 632, 653, 677, 693, 727, 743, 763, 823, 850, 887,
916, 941, 975, 991, 1036, 1119, 1187, 1218, 1235, 1284, 1332,
1377, 1414, 1460, 1495, 1569, 1586, 1601, 1812, 1876, 1959,
2588, 2687, 2856, 2930. 31P–{1H} NMR (36.48 MHz, CDCl3):
δ
P 47.5.
Dibutylꢀ2ꢀ(5ꢀchloroꢀ2ꢀhydroxyphenyl)ꢀ2ꢀphenylethenylphosꢀ
The phosphine oxide derivatives are waterꢀinsoluble, therefore
they were dissolved in 0.1 M solution of TXꢀ100. The stock solutions
with the concentration in the range of 0.014—0.015 mol L–1
was prepared for all of the phosphine oxides studied.
phine oxide (3). 1ꢀBromobutane (4.05 mL, 5.14 g, 37.5 mmol) in
ether (20 mL) was added with stirring in an argon atmosphere to
magnesium chips (0.9 g, 37.5 mmol) preliminary activated with
crystalline iodine and boiled under reflux for 35 min. A solution
of chlorophosphorinine oxide 7 (5 g, 1.61 mmol) in benzene
(5 mL) was added dropwise to the resulting solution. The reacꢀ
tion mixture was boiled for 30 min, cooled, quenched with
water (10 mL) and a solution of hydrochloric acid (4 mL)
in water (10 mL). The organic layer was separated, the solvents
were evaporated. The residue was dried in vacuo (100 °C, 0.1 Torr).
The product (6.0 g, 95%) in the form of brownish oil was
obtained. Found (%): C, 69.86; H, 8.12; Cl, 7.93; P, 6.93.
C22H28ClO2P. Calculated (%): C, 67.60; H, 7.22; Cl, 9.07;
P, 7.92. MS, m/z: 390 [M]+•, 376 [M – OH–], 355 [M – Cl],
333 [M – Bu], 276 [M – 2 Bu], 229 [M – PO(Bu)2], 161.6
[C8H18OP], 57 [Bu], 43.1 [Pr], 29 [Bu]. 31P—{1H} NMR
The extraction was performed by the following procedure:
the chloroform solution of an extractant (5 mL, 0.3 mmol L–1
)
was added to the aqueous solution of Ln(NO3)3 (5 mL, C = 0.17
mmol L–1) with variable acidity (achieved by addition of different
amounts of nitric acid). The twoꢀphase system was magnetically
stirred for 1.5 h in a closed flask and kept for 24 h in darkness.
After separation of the aqueous phase, it was analyzed for the
lanthanide ion content by spectrophotometry with Xylenol
Orange as the indicator.
2ꢀ(5ꢀChloroꢀ2ꢀhydroxyphenyl)ꢀ2ꢀphenylethenyl(dimethyl)ꢀ
phosphine oxide (1). A solution of chlorophosphirinine oxide 7
(13.8 g, 44.4 mmol) in 25 mL of benzene was added dropwise to
the Grignard reagent obtained from magnesium (2.2 g, 92.4 mmol)
and methyl iodide (5.75 mL, 13.1 g, 92.4 mmol) in diethyl ether
(100 mL). The reaction mixture was heated with vigorous stirring
for 30 min (phase separation was observed), after cooling to
∼20 °C it was quenched with 30 mL of water and 8 mL of
hydrochloric acid with vigorous stirring; boiling of ether being
observed. The organic layer was separated, acetone (2—4 mL)
was added and the homogeneous organic layer obtained sediꢀ
mented upon dilution with water. Compound 1 (13.0 g, 96%)
in the form of a brownish powder with m.p. 172—175 °C was
obtained. Found (%): C, 62.61; H, 5.29; Cl, 11.33; P, 10.11.
C16H16ClO2P. Calculated (%): C, 62.65; H, 5.26; Cl, 11.56;
P, 10.10. MS, m/z: 306 [M]+•, 292 [M – CH2], 291 [M – Me],
290 [M – Me – H], 276 [M – 2 Me], 275 [M – 2 Me – H], 271
[M – Cl], 255 [M – Me – HCl], 230 [C14H11ClO], 229
[C14H10ClO], 228 [C14H9ClO], 215, 202, 194, 166,165, 152,
139, 111, 105, 97, 83, 78, 57, 43. IR, ν/cm–1: 422, 452, 534, 567,
637, 694, 759, 819, 879, 910, 940, 954, 1031, 1114, 1138, 1221,
1284, 1303, 1334, 1377, 1409, 1464, 1496, 1573, 1587, 1604,
2582, 2683, 2854, 2924, 3380. 31P—{1H} NMR (36.48 MHz,
DMSOꢀd6): δP 37.0.
(162.0 MHz, DMSOꢀd6): δ 42.38. IR, ν/cm–1: 471, 634, 686,
P
763, 828, 899, 948, 1125, 1222, 1282, 1340, 1415, 1455, 1492,
1590, 2361, 2597, 2720, 2956, 3035.
(5ꢀChloroꢀ2ꢀhydroxyphenyl)ꢀ2ꢀphenylethenyl(dihexyl)phosꢀ
phine oxide (4). 1ꢀIodohexane (5.66 mL, 8.13 g, 38.3 mmol) in
ether (30 mL) was added dropwise with stirring in an argon
atmosphere to magnesium chips (0.92 g, 38.3 mmol) preliminary
activated with crystalline iodine and boiled under reflux for
30 min. A solution of chlorophosphorinine oxide 7 (5 g, 1.61 mmol)
in benzene (5 mL) was added dropwise to the resulting solution.
The reaction mixture was boiled under reflux for 20 min, cooled,
and quenched with water (10 mL) and a solution of hydrochloric
acid (4 mL) in water (10 mL). The organic layer was separated,
the solvents were evaporated. The residue was dried in vacuo
(100 °C, 0.1 Torr). The product (6.9 g, 96%) in the form of
brownish oil was obtained. Found (%): C, 69.56; H, 8.22;
Cl, 8.05; P, 7.03. C26H36ClO2P. Calculated (%): C, 69.86;
H, 8.12; Cl, 7.93; P, 6.93. MS, m/z: 446 [M]+•, 411 [M – Cl],
361 [M – C6H13– H], 276 [M – 2 C6H13], 229 [M – PO(C6H13)2],
43.1 [Pr•]. 31P—{1H} NMR (162.0 MHz, DMSOꢀd6): δ 54.3.
P
2ꢀ(5ꢀChloroꢀ2ꢀhydroxyphenyl)ꢀ2ꢀphenylethenyl(diethyl)phosꢀ
phine oxide (2). A solution of chlorophosphirinine oxide 7 (2.5 g,
8.0 mmol) in 10 mL of benzene was added dropwise to the
Grignard reagent obtained from magnesium (0.43 g, 17.9 mmol)
and ethyl iodide (1.44 mL, 2.8 g, 17.9 mmol) in diethyl ether
(20 mL) and heated under reflux for 0.5 h. The solution was
cooled, quenched with 30 mL of water and 2.3 mL of hydroꢀ
chloric acid. The organic and aqueous layers were filtred and
separated. Then the solvent was evaporated, the solid greenish
residue was washed with 10% hydrochloric acid (15 mL),
separated by decantation, and dried in vacuo. Compound 2 (2.52 g,
IR, ν/cm–1: 699, 766, 824, 887, 975, 1116, 1214, 1278, 1342,
1411, 1458, 1490, 1595, 1884, 2596, 2731, 2861, 2927, 3065, 3737.
5ꢀChloroꢀ2ꢀhydroxyphenyl)ꢀ2ꢀphenylethenyl(dioctyl)phosꢀ
phine oxide (5). 1ꢀIodooctane (26.43 mL, 35.02 g, 145.8 mmol)
in isooctane (60 mL) was added dropwise with stirring in an
argon atmosphere to magnesium chips (3.5 g, 145.8 mmol)
preliminary activated with crystalline iodine and boiled under
reflux for 30 min. A solution of chlorophosphorinine oxide 7
(18 g, 57.9 mmol) in benzene (20 mL) was added dropwise to
the resulting solution. The formation of a white emulsion was
observed, which was boiled under reflux for 40 min, then cooled

2226
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 11, November, 2009
Elistratova et al.
TXꢀ100
L
Ln3+
Aqueous solution
Aqueous
phase
Micellar
phase
Fig. 2. The schematic presentation of micellar extraction.
and quenched with a solution of hydrochloric acid (10 mL) in
water (30 mL). The organic layer was separated, the solvents
were evaporated in vacuo (12 Torr). The residue was dried in vacuo
(100 °C, 0.1 Torr). The product (27.9 g, 96%) in the form of
greenish oil was obtained. Found (%): C, 71.22; H, 9.07;
Cl, 7.15; P, 6.27. C30H44ClO2P. Calculated (%): C, 71.64;
H, 8.76; Cl, 7.05; P, 6.17. MS, m/z: 502 [M]+•, 467 [M – Cl],
389 [M – C8H17], 276 [M – 2 C8H17], 229 [M – PO(C8H17)2],
by decantation and analyzed for the content of lanthanide by
spectrophotometry with Xylenol Orange as an indicator.24 The
degree of extraction (Е) was calculated using equation
Е = 100(A0 – Ai)/A0,
where A0 is the optical density of the initial solution of lanthanide
nitrate (C = 1.7•10–4 mol L–1), Ai is the optical density of the
solutions after extraction. The data obtained were used for
the calculation of stoichiometry and the degree of extraction
(equilibrium (1)) by the graphical solution of Eqs (2) and (3).
228 [M – PO(C8H17)2
– H]. 31P—{1H} NMR (162.0 MHz,
DMSOꢀd6): δ 40.8. IR, ν/cm–1: 409, 472, 536, 567, 634, 671,
P
697, 724, 762, 822, 848, 885, 945, 1031, 1112, 1136, 1223, 1282,
1335, 1378, 1411, 1445, 1467, 1493, 1572, 1591, 1958, 2855,
2926, 2955, 3059.
m Ln3+(aq) + n L(aq) = LnmLn(aq)
(1)
2ꢀButylꢀ2ꢀ(5ꢀchloroꢀ2ꢀhydroxyphenyl)ethenyl(diphenyl)phosꢀ
phine oxide (6). A solution of chlorophosphirinine oxide 7 (10 g,
34.4 mmol) in 10 mL of benzene was added dropwise with stirring
in a flow of argon to the Grignard reagent obtained from
magnesium (1.8 g, 75.0 mmol) and bromobenzene (7.9 mL, 11.9 g,
75.0 mmol) in diethyl ether (100 mL). The reaction mixture was
boiled under reflux for 0.5 h, cooled to ∼20 °C, and quenched
with water (20 mL). The solvents from the organic layer
were evaporated, the glassy residue was dried in vacuo (100 °C,
12 Torr), the yield was 12 g (85%). Found (%): C, 70.24;
H, 6.13; Cl, 8.75; P, 7.73. C24H24ClO2P. Calculated (%): C, 70.16;
H, 5.85; Cl, 8.63; P, 7.55. MS, m/z: 410 [M]+•, 290 [M – Ph – Pr],
277 [M – Ph – Bu], 202 [Ph2PO], 153 [M – Ph2PO – Bu], 152
[M – Ph2PO – Bu – H], 77 [Ph]. 31P—{1H} NMR (162.0 MHz,
According to equilibrium (1), the constant and the logarithm
of extraction degree (Kex and logKex) can be calculated using the
expressions
Kex = [LnmLn]/([L]n[Ln3+]m),
(2)
(3)
logKex = log([LnmLn]/[Ln3+]m) – nlog[L],
where [LnmLn]/[Ln3+ m
= E/(1 – E) at m = 1; [LnmLn] is
]
concentration of the complex; [Ln3+] is the equilibrium concenꢀ
tration of lanthanides in aqueous phase; [L] is equilibrium
concentration of the extractant.
All data given in this work are the average results of at least
two measurements.
DMSOꢀd6): δ 19.7. IR, ν/cm–1: 405, 436, 456, 512, 539, 605,
P
641, 695, 719, 738, 782, 822, 879, 906, 998, 1027, 1071, 1099,
1120, 1156, 1236, 1278, 1378, 1412, 1437, 1489, 1496, 1592,
1817, 1892, 1959, 2247, 2721, 2870, 2929, 2956, 3058.
The work was financially supported by the Russian
Foundation for Basic Research (Project No. 07ꢀ03ꢀ00282).
The procedure of micellar extraction. Micellar extraction was
conducted in 20 mM solution of nonionic surfactant TXꢀ100
containing LnIII (0.17 mmol L–1). The chelating agents (phosꢀ
phine oxide derivatives) were introduced in concentration of
0.2 mmol L–1. The solution was heated to CP, which resulted in
phase separation into the coacervate phase (the heavier one)
and the phase depleted in surfactants (Fig. 2). The solution was
kept at this temperature for 15 min. The cloud point of solutions
of TXꢀ100 in the presence of chelating agents was 65 1 °C,
which is close to that of TXꢀ100 solution. The pH values were
varied by addition of different amounts of nitric acid.
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Received 25 November, 2008;
in revised form 3 July, 2009