This article was downloaded by: [CSIR eJournals Consortium] On: 5 August 2008 Access details: Access Details: [subscription number 779749116] Publisher Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Solvent Extraction and Ion Exchange Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t713597298
4-ACYLBIS(1-PHENYL-3-METHYL-5-PYRAZOLONES) AS EXTRACTANTS FOR f-ELEMENTS M.L.P. Reddy a; Sushanta K. Sahu b; V. Chakravortty b a Regional Research Laboratory (CSIR), Trivandrum, India b Department of Chemistry, Utkal University, Bhubaneswar, India Online Publication Date: 01 November 2000
To cite this Article Reddy, M.L.P., Sahu, Sushanta K. and Chakravortty, V.(2000)'4-ACYLBIS(1-PHENYL-3-METHYL-5-
PYRAZOLONES) AS EXTRACTANTS FOR f-ELEMENTS',Solvent Extraction and Ion Exchange,18:6,1135 — 1153 To link to this Article: DOI: 10.1080/07366290008934725 URL: http://dx.doi.org/10.1080/07366290008934725
PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
SOLVENT EXTRACTION AND ION EXCHANGE, 18(6), 1135-1153 (2000)
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
4-ACYLBIS(1-PHENYL-3·METHYL-5-PYRAZOLONES) AS EXTRACTANTS FOR f-ELEMENTS
M.L.P. Reddy· Regional Research Laboratory (CSIR) Trivandrum - 695019, India Sushanta K. Sahu, V. Chakravortty Department of Chemistry, Utkal University Bhubaneswar - 751 004, India
ABSTRACT The liquid-liquid extraction of early actinides such as thorium(IV) and uranium(VI) and trivalent lanthanoids such as neodymium(III), europium(lIl) and lutetium(lIl) from nitrate solutions was studied using 4sebacoylbis(1-phenyl-3-methyl-5-pyrazolone) (H2SP) and 4-dodecandioylbis(1-phenyl-3-methyl-5-pyrazolone) (H2DdP) in chloroform as extractants. The results demonstrate that these metal ions are extracted into chloroform as Th(SPh, Th(DdP)2, U02(HSP)2, U02(HDdP)2, Ln(SP)(HSP) and Ln(DdP)(HDdP) with H2SP or H2DdP. The equilibrium constants of the above species were deduced by non-linear regression analysis. The results clearly highlight that thorium(IV) can be selectively separated from uranium(VI) and trivalent lanthanoids when extracted from 0.2 molldm3 nitric acid solutions using 4-acylbis(1-phenyl-3-methyl- 5-pyrazolones). Thorium(IV), uranium(VI) and lutetium(lIl) complexes of H2SP were synthesised and characterised by IR and 'H NMR spectral data to further clarify the nature of the complexes.
• Corresponding author: +91-471-491712; E-mail: reddy@csrrltrd.ren.nic.in 1135 Copyright <l:> 2000 by Marcel Dekker, Inc.
www.dekker.com
1136
REDDY, SAHU, AND CHAKRAVORITY
INTRODUCTION
4-Acylpyrazolones form an interesting class of l3-diketones capable of extracting metal ions from relatively strong acidic solutions due to their lower pKa values (2.56 - 4.01) as Compared to familiar l3-diketone 2thenoyltritluoroacstona (pI(" = 6.25) [1.:4). The nature of the substitueni in the 4-position of pyrazolons ring causes :?ignificant variations in the Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
electronic, steric and solubility parameters of the ligand, thereby affecting complexation and extraction benaviour. A number of 4-acylbis(1-phenyl-3methyl- 5-pyrazo!Qne) derivatives
two
~hown
in Fig.1 were dl1lsigned in which
1-phenyl-3-m~~hyl-4-acyl-5-pyrazolone
subunits are linked by a
polymethylene chain of varying length and utilised for the extraction of some transition metals [5-7]. As the 4-acy1bil!( 1-phenyl-3-:methyl- 5pyrazolone) derivatives (H2L) have two ~-diketone donor sites on both ~ides
of polymethylene chains, they are expected to give rise to specific
complexations depending upon the polymethylene chain length. Recently, extraction of uranium(VI) and vanadium(V) with 4-adipolyl and 4-sebacoyl derivatives of 1-phenyl-3-methyl-5-pyrazolone from chloride solutions has been investigated by Uzoukwu et al [8).lt was reported that the addition of decanol to the organic phase resulted in enhancement in the extraction of vanadium(V) and diminution in the extraction of uranium(VI) at higher Hel coricentrations.
Fig. 1. n
=8 (H2SP), 10 (H2DdP)
1137
EXTRACTANTS FOR f-ELEMENTS
This paper reports on the selective extraction of thorium(IV) over uranium(VI) and trivalent lanthanoids using 4-sebacoylbis(1-phenyl- 3methyl-5-pyrazolone) (H2SP) or 4-dodecandioylbis(1-phenyl-3-methyl- 5pyrazolone) (H2DdP) and the stoichiometry of the complexes extracted into the organic phase.
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
EXPERIMENTAL
Chemicals 4-Sebacoylbis(1-phenyl-3-methyl-5-pyrazolone) dodecandioylbis(1-phenyl-3-methyl-5-pyrazolone)
(H2SP) (H2DdP)
and
4-
were
synthesised by the acylation of 1-phenyl-3-methyl-5-pyrazolone with corresponding acid dichlorides following Jensen's method [9]. The purity of the compounds was established by IR and lH NMR spectral data. Stock solutions of thorium(IV) and uranium(VI) were prepared by dissolving appropriate amounts of Th(N03)4.6H20 (Loba-Chemie, India) and U02(N03)2.6H20 (Loba-Chemie, India) in distilled water. The initial metal ion concentration was maintained at 1x1 0-4 molldm3 for thorium(IV) and 5x10-4 molldm3 for uranium(VI) for all extraction studies. Stock solutions of lanthanoids were prepared from their respective oxides by dissolving in concentrated nitric acid and diluting with distilled water to required volume. Initial lanthanoid ion concentration was maintained at 1x10-4 molldm3 for all extraction studies. Ionic strength was maintained at 1 mol/dm3 using NaN03. All organic phase solutions were prepared by dissolving weighed amounts of H2SP or H2DdP in chloroform and diluting to the required volume. Arsenazo III solution was prepared by dissolving 250 mg of the reagent in 250 cm3 of distilled water for determination of thorium(IV) or uranium(VI).
Arsenazo I solution was prepared by dissolving 25 mg of the reagent in 250 cm3 of distilled water for
1138
REDDY, SAHU, AND CHAKRAVORTIY
determination of trivalent lanthanoids. Ammonium acetate buffer (pH=7.5) was prepared by dissolving 19.25 gm in 250 cm3 of distilled water and adjusting the pH with HCI/NaOH. All other chemicals used were of analytical grade. Solvent extraction procedure Distribution ratios were determined by shaking equal volumes of Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
aqueous and organic phases for 2 hours in a glass stoppered vial with the help of a mechanical shaker at 303Âą10 K.
Preliminary experiments
showed that the extraction equilibrium was attained within 60 min for trivalent lanthanoids and 90 min in the case of early actinides.
The
solutions were allowed to settle, centrifuged, separated and assayed spectrophotometrically using a Hitachi 200 double beam microprocessor based spectrophotometer.
Both thorium(IV) and uranium(VI) were
determined spectrophotometrically as their Arsenazo III complexes in 1 rnol/drrr' HCI solution at 660 and 656 nm respectively. The absorbances of the complexes were measured within 5 min of mixing. Lanthanoids were determined spectrophotometrically as their Arsenazo I complexes in ammonium acetate buffer of pH=7.5 at 575 nm. The metal concentrations in the aqueous phase were computed from the respective calibration graphs. The concentration of the metal ion in the organic phase was then obtained by a material balance.
These concentrations were used to
calculate the distribution ratio, D. All the computer programs were written in FORTRAN 77 and executed on a Pentium PC. Preparation of metal complexes 4-Sebacoylbis(1-phenyl-3-methyl-5"pyrazolone) (0.257 gm, 0.50 mmol) was dissolved in 30 cm3 of methanol by adding an aqueous ammonia solution (2 mol/dm3) and then the pH of this solution was adjusted to 5-6 with dilute HN03 solution. Methanol solution of thorium
1139
EXTRACTANTS FOR f-ELEMENTS
nitrate or uranyl nitrate or lutetium nitrate (0.25 mmol) was added to the H2SP methanol solution and a precipitate appeared immediately. The precipitate was filtered after being stirred for 4 hours and washed with dilute HN03 solution until no metal ion and NH4+ could be detected in the washings. Then the precipitate was washed with distilled water. Finally the products were dried at 3130K after being washed for 2 or 3 times with chloroform. The Nicolet Impact 4000 IR spectrometer using potassium Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
bromide pellet was used to obtain IR spectral data and the Bruker 300 MHz NMR spectrometer was used to obtain the 1 H NMR spectra of complexes in COCb.. OMSO..Os mixture.
RESULTS AND DISCUSSION
The extraction equilibrium of a metal ion, Mn+, with a chelating extractant
4..acylbis(1..phenyl..3-methyl..5..pyrazolone),
H2L,
may
be
expressed as:
aMn+ .. + (b + c)H2L
Ku ~.
....M.L.(HL}c
..
=[M.L. (HL)c J[W](2.+C)
K
(1)
(2)
[M n+]" [H2L](.<C)
ex
+ (2b + c}W ..
where Kex denotes the equilibrium constant. The distribution ratio, 0 of metal ion is given by
D=
a[M.L. (HL)c]
n+](1
[M where
p,
.. + P,[N0 3 ' ] + P2[N0 3']2)
..
(3)
is the stability constant of the metal ion with nitrate ion in the
aqueous phase. The values of stability constants were obtained from literature [10..12]. From Eq.(2) and Eq.(3) the distribution ratio of the metal ion can be written as
1140
REDDY, SAHU, AND CHAKRAVORlTY
D
=
aK [H L]"+C[M n+]O-1 ox
2
[W]2b+C (1 + P,[N0 3 ' ] + P2[N0 3']2)
(4)
Taking logarithms log 0
=log Keâ&#x20AC;˘ + (a-1) log [Mn+] + (b+c) log [H2L] + log a - (2b+c) log [WI - log (1 + I3I[NO-3] + MNO-3]2)
(5)
Thus it can be seen that at constant equilibrium pH and [H2L]eq
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
d(logD) d(log[Mn+ ])
a -1
(6)
at constant [Mn+]eq and [H2L]eq d(logD) d(pH)
2b + c
(7)
and at constant equilibrium pH and [Mn+]eq d(logD) b+c d(log[H2L])
(8)
Evaluation of these partial derivatives by slope analysis method allowed the stoichiometry of the extraction equation to be elucidated for each of the investigated extraction systems. The extraction of thorium(IV), uranium(VI) and trivalent lanthanoids with H2SP or H2DdP in chloroform as a function of metal ion concentration, pH and extractant concentration were studied. Plots (Figs.2-6) of log 0 versus log equilibrium concentration of [Th4+], equilibrium pH and log equilibrium concentration of [H2L] gave slopes of 0, 4 and 2, respectively, with both extractants for the extraction of thorium(IV). In the case of extraction of uranium(VI) plots (Figs.2-6) of log 0 versus log equilibrium concentration of [uol+], equilibrium pH and log equilibrium concentration of [H2L] gave slopes of 0, 2 and 2, respectively, with both extractants. On the other hand, plots (Figs.7-11) of log 0 versus log equilibrium concentration of [Ln3+] equilibrium pH and log equilibrium concentration of [H2L] gave slopes of 0, 3 and 2 respectively with both the extractants for the extraction of trivalent lanthanoids.
On substitution of these slope
values into Eq.(6) - Eq.(8), the values obtained for a, band c were 1, 2, 0;
EXTRACTANTS FOR f-ELEMENTS
1141
0.5
Th(lVl
~
0.4
0
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
.
b
0.6
...
U(VI)
0.3
Cl 0
....I
Slope = 0
a
•
0.2
~
0 Cl 0
0.2
-0.2
0.1
-0.6
0
....I
-1
-5
-4.5
-4
-3.5
-3
-2.5
Log [M"-)
Fig. 2. Effect of metal ion concentration on the extraction of thorium(IV) and uranium(VI) with H2SP: (a) H2SP = 5x10· 4 molldm 3 in CHCI3 for Th"'; HN03 = 0.2 mol/dm 3, (b) H2SP = 0.1 molldm3 in CHCb for uoi+; HN03 = 0.2 mol/dm 3.
1.2 0.8
0
l'
Slope=4.0
0.4
U(V1) b
8'
....I
0 -0.4 -0.8
0.6
0.6
1.0
1.2
1.4
pH
Fig. 3. Effect of hydrogen ion concentration on the extraction of 3 thorium(IV) and uranium(VI) with H2SP: (a) H2SP = 5x10-4 molldm 3 3 in CHCb, Th"'= 1x10-4mol/dm , (b) H2SP = 0.05 mol/dm in CHCb; UOi+=5x10-4 mol/dm 3 .
1142
REDDY, SAHU, AND CHAKRAVORTTY
1.2 Slope
Th(IV)
0.8
0
a
0.4
8'
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
~
=2.0
U(VI)
b
I
0
-0.4
-0.8 -3.8
-3.0
-2.2
-1.4
-0.6
Log [H2SPj
Fig. 4. Effect of H2SP concentration in the extraction of thorium(IV) and uranium(VI): (a) Th4+ 1x10-4 mol/dm 3; HN03 0.2 mol/dm3 , (b) uol+ =5x10-4 mol/dm3; HN03 =0.2 mol/dm3.
=
=
1.5 r - - - - - - - - - - - - - ,
0.5
-0.5
-1.5 L-_---'-_ _' - - _ - " - _ - l 0.2
0.6
1.0
1.4
1.8
pH
Fig. 5. Effect of hydrogen ion concentration on the extraction of . thorium~IV) and uranium(VI) with H2DdP: (a) H2DdP = 5x10-4 mol/dm in CHCb, Th4+ = 1x10-4 mol/dm3, (b) H2DdP = 0.05 mol/dm3, uol+ =5x10-4 mol/dm3.
EXTRACTANTS FOR f-ELEMENTS
1143
1.4 Th(IV)
0.8
U(Vl)
0.2
c
I"
e> 0
...J
.Q.4
-1.0 Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
=2.0
Slope
a
-1.6 -3
-4
-2
-1
a
Log [H,OdP]
Fig. 6. Effect of H2DdP concentration on the extraction of thorium(IV) and uranium (VI): (a) Th~ = 1x10-4 mol/dm3 , HN0 3 = 0.2 mol/dm3 , (b) = 5x10-4 molldm 3 , HNOJ = 0.05 mol/dm3 .
uol+
0.3 Slope = 0
0.2
.
0
.§'
..
0.1
• • •
0 -0.1 -4.6
-4.2
-3.8
-3.4
-3.0
Log [Lu3+] Fig. 7. Effect of metal ion concentration on the extraction of lutetium(lIl) 3 with H2SP; H 2SP = 0.01 mol/dm in CHC!J; pH = 3.0
1144
REDDY, SAHU, AND CHAKRAVORTTY
1.5 , . . - - - - - - - - - - - - , Slope
~"'I"'I
o
-05
/
...J
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
Lu(lIl)
/EU(III)
0.5
8'
=3.0
-1.5 -2.5 2.8
3.0
3.4
3.2
3.6
pH
Fig. 8. Effect of pH on the extraction of trivalent lanthanides with H2SP: H2SP 0.01 mol/dm 3 in CHCb, Ln3+ 1x10"" mol/dm3 .
=
=
1.6 Slope = 2.0
0.8 Nd(lII)
o
8'
.:
0
...J
-0.8 -1.6
-2.5
-2.0
-1.5
-1.0
Log [H 2SPJ
Fig. 9. Effect of H2SP concentration on the extraction of trivalent lanthanides: Ln3+ = 1x10"" molldm3 , pH = 3.0.
EXTRACTANTS FOR f-ELEMENTS
1145
1.0 Slope = 3.0 0.4 0
go
-D.2
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
..J
-D.6 -1.4 2.6
3.0
3.2
3.4
3.6
pH
Fig. 10. Effect of pH on the extraction of trivalent lanthanides with H2DdP: H2DdP = 0.01 molldm3 in CHCb; Ln3+ = 1x10"" molldm3 .
1.0 Slope =2.0 Eu(lII) 0.2 0
go
..J
-D.6
-1.4 -2.5
-2.0
-1.5
-1.0
Log [H 2DdP)
Fig. 11. Effect of H2DdP concentration on the extraction of trivalent lanthanides: Ln3+ 1x10"" mol/dm3 ; pH 3.0.
=
=
1146
REDDY, SAHU, AND CHAKRAVORlTY
1, 0, 2; and 1, 1, 1 for the extraction of thorium(IV), uranium(VI) and trivalent lanthanoids, respectively. Substituting these values into Eq.1 yields Th 4 ' ., +2H 2L .,
(9) K"U
U0 2 2... + 2H2L ., .... U0 2 (HL), ., + 2W ..
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
K
Ln3+ .. + 2H2L ., where Ln3+
=Nd3
+,
(10)
ln
Ln(L)(HL)., + 3W ..
(11)
Eu3+ and Lu3+.
The above extraction equilibria indicate that two moles of H2L interact with one mole of Th4+ through both the [3-diketone donor sites of H2L, releasing four moles of hydrogen ion. In the case of uranium(VI),
two moles of H2L interact with one mole of uol+ through one of the [3diketone donor sites of the ligand, releasing two moles of hydrogen ion. On the other hand, Ln3+ interact with two moles of H2L through both [3diketone donor sites of one mole of H2L and one [3-diketone donor site of the another mole of H2L, thereby releasing three moles of hydrogen ion in the process (Fig. 12). The formation of the above metal chelates was further confirmed by analysing the equilibrium data using Eq.(4) for thorium(IV), uranium(VI) and trivalent lanthanoids.
The equilibrium constants for the above
complexes were determined by non-linear regression analysis (as described in our earlier publication [13]) and are shown in Table 1. It is clear from Table1 that the log equilibrium constant (log Kex) value of thorium(IV), uranium(VI) and trivalent lanthanoids decrease from H2SP to H2DdP. This has been attributed to the increase in steric effect, caused by increase in polymethylene chain length (from n
=8 to n =10).
The results (Figs.2 and 6) clearly demonstrate that thorium(IV) can be selectively separated from uranium(Vl) at 0.2 mol/dm3 HN03 solution using 0.1 mol/dm3 H2SP in chloroform as an extractant (separation factor
=
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
EXTRACTANTS FOR f-ELEMENTS
1147
Fig.12 . Extracted complexes of thorium(IV), uranium(VI) and trivalent lanthanoids with 4-acylbis( 1-phenyl-3-methyl-5-pyrazolone)
Table 1. Two phase equilibrium constants of f-elements with various 4-acylbis( 1-phenyl-3-methyl-5-pyrazolones) Metal ion
Log equilibrium constant H2DdP
Nd(lII)
-6.26±O.02
Eu(llI)
-5.48±O.03
-5.66±O.03
Lu(lIl)
-4.65±O.03
-5.09±O.03
Th(lV)
5.12±O.02
3.98±O.02
U(VI)
O.79±O.03
O.25±O.02
1148
REDDY, SAHU, AND CHAKRAVORTIY
Table 2. Elemental analyses of the complexes
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
Complex
C% N% H% M% Found Calc. Found Calc. Found Calc. Found 57.54 8.91 8.84 5.10 4.88 18.45 18.40
Th(SP)2
Calc. 57.23
U02(SP)
46.04
46.06
7.16
7.18
4.09
4.44
30.43
30.35
LU2(SPh
57.23
57.42
8.90
9.23
5.09
5.35
18.54
18.50
=9.2x104 ) or 0.05 molldm3 H20dP in chloroform (separation factor = OTtJOU = 3.3x104 ) . Further, the extraction of trivalent lanthanoids from
OTtJOU
0.2 rnol/dm, HN03 solution was found to be negligible when 0.1 molldm 3 H2SP or 0.05 molldm3 H2DdP in chloroform were used. However, these trivalent lanthanoids were found to be extracted with H2SP or H2DdP from nitrate solution of pH
= 3.0. Thus,
it can be concluded from the above
study that thorium(lV) can be selectively separated from uranium(VI) and trivalent lanthanoids when extracted from 0.2molldm3 HN03 solution using 4-acylbis(1-phenyl-3-methyl- 5-pyrazolones). Elemental Analyses of the complexes Table 2 contains the elemental analyses of the complexes. C, H and N analyses were perfomed with a Perkin Elmer Series 2 Elemental Analyser 2400.
Metal ions in the complexes were determined by the
following method : a certain quantity of complex was decomposed by heating in a small amount of HN03 solution and excess acid was evaporated. This was diluted with distilled water and finally uranium and thorium were determined spectrophotometrically as their Arsenazo III complexes and lutetium was determined spectrophotometrically as its Arsenazo I complex. It is known from Table 2 that the composition of the complexes is Th(SP)2, U02(SP) and LU2(SPh.
EXTRACTANTS FOR f-ELEMENTS
1149
IR spectra The IR spectra of the extracted complexes showed that the stretching frequency of the C=O in H2SP has shifted from 1626 ern" to 1602 em" for thorium complex; 1626 ern" to 1608 ern" for uranyl complex and 1626 em" to 1619 em" for lutetium complex, which indicates that the carbonyl group is involved in the bonding. These data further confirm that there is a stronger interaction between 4-acylbis(1-phenyl-3-methyl-5Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
pyrazolone) and thorium(lV) than that of uranium(VI) and lutetium(III), which is also evident from the equilibrium constant values of these felements with H2SP. The other strong absorption at 927 ern" in the uranyl complex may be assigned to v(O=U=O) of U022> [14]. The absorption peak at 419 em" in the lutetium complex may be assigned to Lu-O stretching frequency [15]. The presence of the broad absorption peak at 3414 ern" - 3426 em" [15] for all the metal complexes indicates the existence of water molecule in the complexes. 'H NMR spectra Table 3 contains the 1H NMR spectral data for H2SP and metal complexes of thorium(IV), uranium(VI) and lutetium(lIl) with H2SP in CDCb - DMSO-D6 mixture. The methyl proton of the free ligand H2SP was observed as a singlet at 2.47 ppm and the methylene proton signals were observed at 2.71-2.76 ppm as a triplet. 1.72-1.75 ppm as a multiplet and 1.40 ppm as a singlet.
The phenyl proton signal was observed as a
multiplet at 7.25-7.84 ppm. The hydroxyl proton of enolic form of the H2SP ligand was observed at 9.43 ppm. In the complexes, the lH NMR spectra contain greater shifts and changes in comparison with the 'H NMR of the H2SP ligand. In the 'H NMR spectra of Th-H2SP complex, the disappearance of the peak at 9.43 ppm due to enolic OH proton of H2SP indicates the ionisation of enolic OH group and involvement of oxygen hydroxyl group in chelation. It is evident
2.34 (5, 12H) 2.60 (5, 6H)
2.13 (5, 12H); ,2.38 (5, 6H)
7.02 - 7.92 (m, 20H 7.26 - 8.25 (m, 10H)
7.12 - 7.99 (m, 30H)
Th - H2SP
U -H2SP
Lu - H2SP
br = broad; s = singlet; m
H2SP
= multiplet
Enolic OH 9.43 (br, 5, 2H)
Methyl 2.47 (5, 6H)
Compound
Phenyl 7.25 - 7.85 (m, 10H)
Methylene 2.71 - 2.76 (t, 4H, CH 2) ; 1.72 - 1.75 (m, 4H, CH 2) ; 1.40 (s, 8H, CH 2) 2.38 - 2.77 (m, 8H); 1.22 - 1.62 (m, 24H) 3.23 (s, 4H, CH 2) ; 2.12 (s, 4H, CH 2) ; 1.63 (s, 8H, CH 2) 2.38 - 2.59 (m, 12H, CH 2) 1.34 - 1.67 (m, 36H, CH2)
Table 3. lH NMR spectral data for the ligand and complexes
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
e
~
o<
~
S;
o
~ o
~
>
til
.~
g;
o '"
1151
EXTRACTANTS FOR f-ELEMENTS
from the extraction studies that two moles of H2SP interacted with one mole of
uol+
through one of the J3-diketone donor sites of the ligand,
releasing two moles of hydrogen ion. Thus in the 1 H NMR spectra of the solid complex a broad peak should be observed at 9.43 ppm due to two enolic OH protons. However, this peak was not observed in the 1H NMR spectra of U - H2SP complex. This may be due to the formation of U02(SP) complex in the solid state as reported elsewhere [16). The Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
disappearance of the enolic OH peak in the 1H NMR spectra of Lu - H2SP complex may be due to the formation of a 2:3 lutetium to H2SP complex as reported by Li et al. [15] in the complexation of lanthanoids with bispyrazolones. In the lutetium complex the integrated intensity of methyl proton is in the ratio 2: 1; the ratio shows that the structure of the complexes have non-equivalent ligands with possibly a 2:3 lutetium to ligand ratio. The formation of the above complexes was further supported by elemental analysis data.
CONCLUSION The extraction equilibria of thorium(IV), uranium(Vl) and trivalent lanthanoids with
H2SP and H2DdP have
been investigated.
The
equilibrium constant values of these metal ions were found to decrease with an increase of the polymethylene chain length (n = 8 to n = 10). Very high
selectivities
have
been
observed
between
thorium(lV)
and
uranium(Vl) and trivalent lanthanoids when extracted from nitric acid solutions using 4-acylbis(1-phenyl-3-methyl-5-pyrazolones). Thus, these extraction systems may find potential applications in the separation of thorium(lV) from uranium(Vl) and rare earths.
ACKNOWLEDGEMENTS This work was supported by Council of Scientific and Industrial Research, New Delhi. The authors wish to thank Dr. G.D. Surender, Head,
1152
REDDY, SAHU, AND CHAKRAVORTIY
Mineral Processing Division and Dr. G.vijay Nair, Director, Regional Research Laboratory, Trivandrum, for their constant encouragement
REFERENCES 1.
Y. Sasaki and H. Fraiser, Inorg. Chem., 22, 2289 (1983).
2.
C. Yonezawa, and G.R Choppin, J.Radioanal.
Nucl. Chem.
Articles, 134,233 (1989). Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
3.
P.B. Santhi, M.L.P. Reddy, T.R Ramamohan, AD. Damodaran, J.N. Mathur, M.S. Murali and RH. Iyer, Solvent Extr. Ion Exch., 12, 633 (1994).
4.
R Luxmi Varma, S. Sujatha, M.L.P. Reddy, T.P. Rao, C.S.P. Iyer and A.D. Damodaran, Radiochim. Acta, 72, 133 (1996).
5.
S. Miyazaki, H. Mukai, S. Umetani, S. Kihara and M. Matsui, Inorg, Chem., 28, 3014 (1989).
6.
S. Miyazaki, H. Mukai, S. Umetani, S. Kihara and M. Matsui, Anal. Chim. Acta, 249, 525 (1991).
7.
BA Diantouba, I. Guiguemde, A. Tayeb, G.J. Goetz-Grandmont and J.P. Brunette, Solvent Extr. Ion Exch., 12,325 (1994).
8.
BA Uzoukwu, K. Gloe and H. Duddeck, Solvent Extr. Ion Exch., 16, 751 (1998).
9.
B.S. Jensen, Acta Chem. Scand. 13, 1668 (1959).
10.
B.G. Oliver and AR. Davis, J. Inorg. NucI.Chem., 34, 2851 (1972).
11.
S. Kotrly and L. Sucha, Handbook of Chemical Equilibria in Analytical Chemistry, Ellis Horwood, Chichester, WS England (1985).
12.
R.M. Smith and AE. Martell, Critical Stability Constant, VolA, Plenum Press, New York (1976).
13.
M.L.P. Reddy, S. Sujatha, R. Luxm! Varma, T.R Ramamohan, T.P. Rao, C.S.P. Iyer and AD. Damodaran, Talanta, 44, 97 (1997).
14.
P. Thakur, V. Chakravortly, K.C. Dash, T.R. Ramamohan and M.L.P. Reddy, Radiochim. Acta, 80,155 (1998).
EXTRACTANTSFOR~ELEMENTS
15.
X.
u.
H. Wanyan, W. Dong and R. Yang, Polyhedron,
1153 ~,
2285
(1990).
16.
BA Uzoukwu and E.C. Okafor, Synth. React. Inorg. Met-Org. Chern. 21, 825 (1991)
Downloaded By: [CSIR eJournals Consortium] At: 06:32 5 August 2008
Received by Editor February 14, 2000