Extraction of Uranium(VI), Thorium(IV), and Trivalent Rare Earths from Nitric Acid Solutions with {[2-(2-Diphenylphosphoryl)-4-ethylphenoxy]ethyl}diphenylphosphine Oxide

Article abstract of DOI:10.1134/S1070363220060122

Abstract: A new extractant, {[2-(2-diphenylphosphoryl)-4-ethylphenoxy]ethyl}diphenylphosphine oxide, has been synthesized, and its solutions in 1,2-dichloroethane and a ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, have been used to extract HNO₃, uranium(VI), thorium(IV), and trivalent rare earths from nitric acid solutions. The stoichiometry of the extracted complexes has been determined, and the effects of the extractant structure and HNO₃ concentration in the aqueous phase on the extraction efficiency have been studied. The extraction efficiency has been found to significantly increase when ionic liquid is present in the organic phase.

Full text of DOI:10.1134/S1070363220060122

ISSN 1070-3632, Russian Journal of General Chemistry, 2020, Vol. 90, No. 6, pp. 1012–1019. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Obshchei Khimii, 2020, Vol. 90, No. 6, pp. 919–928.
Extraction of Uranium(VI), Thorium(IV),
and Trivalent Rare Earths from Nitric Acid Solutions
with {[2-(2-Diphenylphosphoryl)-4-ethylphenoxy]ethyl}-
diphenylphosphine Oxide
a,
b
c
d
A. N. Turanov *, V. K. Karandashev , D. V. Baulin , and V. E. Baulin
a
Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, 142432 Russia
b
Institute of Problems of Microelectronics Technology and High-Purity Materials, Russian Academy of Sciences,
Chernogolovka, 142432 Russia
c
Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, 119991 Russia
d
Institute of Physiologically Active Substances, Russian Academy of Sciences, Chernogolovka, 142432 Russia
*
e-mail: turanov@issp.ac.ru
Received February 4, 2020; revised February 4, 2020; accepted February 16, 2020
Abstract—A new extractant, {[2-(2-diphenylphosphoryl)-4-ethylphenoxy]ethyl}diphenylphosphine oxide,
has been synthesized, and its solutions in 1,2-dichloroethane and a ionic liquid, 1-butyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)imide, have been used to extract HNO , uranium(VI), thorium(IV), and trivalent
3
rare earths from nitric acid solutions. The stoichiometry of the extracted complexes has been determined, and the
effects of the extractant structure and HNO concentration in the aqueous phase on the extraction efficiency have
3
been studied. The extraction efficiency has been found to significantly increase when ionic liquid is present in the
organic phase.
Keywords: phosphoryl podands, extraction, rare earths, ionic liquids
DOI: 10.1134/S1070363220060122
Extraction methods are widely used for the isolation,
concentration, and separation of actinides and rare earths
butyl led, respectively to increase or sharp decrease
of the extraction ability for actinides and REs in nitric
acid medium [14] due to the effect of “anomalous aryl
strengthening” of the extracted complexes [15]. This
effect has been repeatedly discussed in the literature
[16–18]. Introduction of an ethyl group into the 4-position
of the phenylene fragment of {2-[(diphenylphosphoryl)-
methoxy]phenyl}diphenylphosphine oxide improved
the solubility in organic solvents and reduced extractant
transfer to the aqueous phase [19]; however, the effect on
the extraction ability for RE(III) was insignificant. The
influence of conformational rigidity and length of the
hydrocarbon bridge between the phenolic oxygen atom
(
RE) from nitric acid medium [1]. A high extraction
ability for these elements was demonstrated by neutral
multidentate organophosphorus compounds [2, 3]; among
the latter, substituted methylenedi(phosphine oxides) [4],
(dialkylcarbamoylmethyl)diarylphosphine oxides [5], and
acyclic analogs of crown ethers (podands) containing
amide [6–11] or phosphoryl terminal groups [12–14]
have been studied in most detail.
The extraction ability and selectivity of phosphoryl-
substituted podands are largely determined by the
polyether chain length, conformational rigidity of their
molecules, and nature of substituents on the phosphorus
atoms [12–14]. Derivatives of {2-[(diphenylphosphoryl)
methoxy]phenyl}diphenylphosphine oxide 2 (Scheme 1)
showed a high extraction ability for actinide and RE(III)
ions [14] and was superior to (dialkylcarbamoylmethyl)
diarylphosphine oxides. Replacement of phenyl
substituents in the phosphoryl groups by p-tolyl or
and CH P(O) in structural analogs of phosphine 2 has
2
been studied to a much lesser extent [20].
In recent time, there has been increased interest in
the use of ionic liquids for extraction/concentration and
separation of organic and inorganic compounds [21–24].
The extraction of actinides and RE(III) with neutral
bidentate organophosphorus compounds [25–27] and
1
012

EXTRACTION OF URANIUM(VI), THORIUM(IV), AND TRIVALENT RARE EARTHS
1013
Scheme 1.
O
P
O
P
Ph
Ph
Ph
Ph
n
O
P
n
O
P
O
O
R
Ph
Ph
Ph
Ph
1
ꢀ4
5 7
ꢀ
R = H, n = 0 (1), 1 (2), 3 (3); R = Et, n = 2 (4, 6), 1 (5), 3 (7).
substituted diglycolamides [28–30] was significantly
[HNO ] > 2 M, the concentration ratio of HNO bound
3 3
improved in the presence of ionic liquids such as 1-alkyl-
in a complex with the extractant and extractant in the
organic phase is higher than unity.
3
-methylimidazolium bis(trifluoromethanesulfonyl)-
imides. In these systems, there was no need to use a
large excess of nitrate ions in the aqueous phase to
achieve quantitative extraction of RE(III), though this
is a necessary condition for the extraction with the same
extractants in traditional organic solvents. The effect
of ionic liquids on the extraction of metal ions with
phosphoryl podands has been poorly studied [31].
Assuming that extractant (L) complexes with one and
two nitric acid molecules are transferred to the organic
phase, the extraction process can be described by Eq. (1).
+
–
i(H + NO ) + L(o) ↔ (HNO ) L ,
(1)
3
(w)
3 i (o)
where the subscripts “(w)” and “(o)” refer to the aqueous
and organic phase, respectively, and i = 1 or 2 is the
number of HNO molecules in the extracted complex.
3
The goal of the present work was to study how the
structure of {2-[(diphenylphosphoryl)methoxy]phenyl}-
diphenylphosphine derivatives affects their extraction
ability for uranium(VI), thorium(IV), and trivalent RE ions
from nitric acid solutions and how the ionic liquid 1-butyl-
The effective HNO extraction constants (K and K )
3
1
2
are given by Eq. (2).
i
K = [(HNO ) L]/([L]a ),
(2)
i
3 i
where a is the activity of HNO in the equilibrium aqueous
3
3
-methylimidazolium bis(trifluoromethanesulfonyl)-
+
–
2
phase, a = [H ][NO ]γ ; and [L] is the equilibrium
3
±
imide (C mimTf N) affects the extraction of metals from
4
2
concentration of the free extractant in the organic phase.
HNO solutions with {[2-(2-diphenylphosphoryl)-4-
3
Table 1 contains the K and K values calculated by
1
2
ethylphenoxy]ethyl}diphenylphosphine oxide 4.
the non-linear least squares method using Eq. (3). For
Previously unknown [2-(2-diphenylphosphoryl)-
comparison, the K and K values for compound 2 are
1
2
4
-ethylphenoxy)ethyl]diphenylphosphine oxide 4 was
also given therein.
synthesized in three steps according to Scheme 2. The
reaction of (5-ethyl-2-hydroxyphenyl)diphenylphosphine
oxide with an equimolar amount of 2-chloroethanol in a
sealed ampule at 100–120°C for 12 h gave compound 4a
which was converted to chloro derivative 4b by heating
with phosphorus pentachloride under reflux. Compound
2
2
y/[L](init) = (K a + 2K a )/(1 + K a + K a ).
(3)
1
2
1
2
Here, y is the overall concentration of HNO complexes
with extractant in the organic phase, and [L](init) is the
initial extractant concentration.
3
The higher extraction ability of compound 4 for
4
b reacted with trimethylsilyl diphenylphosphinite
HNO may be related to the longer distance between
3
generated in situ from diphenylphosphinous acid and
hexamethyldisilazane to afford target product 4 in a high
yield.
the phosphoryl groups of the extractant molecule.
Increase of the HNO extraction constants in the series
3
of alkylenedi(diphenylphosphine oxides) with increase
of the length of the alkylene bridge between the P(O)
groups was noted previously [32]; it was explained by
increase of the donor ability of the coordinating groups
of the extractant due to weakening of the inductive effect
of the phosphoryl groups as they become more distant
from each orther.
Taking into account that extraction of metal ions from
nitric acid solution with organophosphorus compounds
is accompanied by reaction of the latter with HNO , we
3
preliminarily studied extraction of HNO with a solution
3
of 4. The data for HNO partition between aqueous phase
3
and a solution of 4 in dichloroethane showed that at
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 90 No. 6 2020

1014
TURANOV et al.
Scheme 2.
OH
P
O
P
OH
O
P
Cl
(
1) NaH
PCl
5
O
O
O
(2) ClCH CH OH
2
2
Ph
Ph
Ph
4b
Ph
Ph
Ph
CH3
CH3
CH3
4
a
Ph P–OSiMe3
2
O
Ph
Ph
O
P
O
P
Ph
Ph
CH
3
4
Weexaminedtheeffectoftheequilibriumconcentration
of increase of the energy of hydration of Ln3+ ions due
of HNO in the aqueous phase on the partition coefficients
to decrease of their ionic radii with rise in Z. This leads
3
of U(VI), Th(IV), and RE(III) in the extraction with
to increase of the separation coefficient Lu/La, βLu/La
=
a solution of 4 in dichloroetane (Fig. 1). The plots of
D /D , as the HNO concentration increases (Fig. 1).
Lu La
3
partition coefficients (D) versus HNO concentration
Similar D —[HNO ] dependences were observed for the
3
Ln 3
showed a maximum, which is related to the salting-out
extraction of RE(III) (as coordinatively solvated nitrates)
with solutions of 2 [32]. The efficiency of extraction of
RE(III) with compound 4 from nitric acid solutions tend
to increase with rise in Z. This is related to increase of
the stability of RE(III) complexes with hard (according
to Pearson) ligands as the charge density on Ln3 ion
–
effect of NO and complexation of the extractant with
3
nitric acid. In the extraction of rare earth ions, the position
of the maximum on the logD —log[HNO ] curve shifts
Ln
3
toward higher acidity of the aqueous phase as the atomic
number (Z) of the element increases. This is the result
+
log [HNO3]
log [L]
Fig. 1. Plots of (1) Th(IV), (2) U(VI), (3) Lu(III), (4) Tb(III),
(
5) Eu(III), (6) Nd(III), and (7) La(III) partition coefficients
Fig. 2. Plots of (1) Th(IV), (2) U(VI), (3) Lu(III),
(4) Tb(III), (5) Eu(III), and (6) Nd(III) partition coefficients
versus concentration of compound 4 in dichloroethane in the
versus equilibrium HNO concentration in the aqueous phase
in the extraction with (1, 2) 0.03 and (3–7) 0.1 M solutions of
compound 4 in dichloroethane.
3
extraction from 3 M HNO solutions.
3
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EXTRACTION OF URANIUM(VI), THORIUM(IV), AND TRIVALENT RARE EARTHS
1015
Table 1. Effective constants for the extraction of nitric acid
with solutions of 2 and 4 in dichloroethane
Table 2. Effective constants for the extraction of RE(III)
from HNO solutions with solutions of compounds 2 and 4 in
3
dichloroethane
Compound no.
K1
K2
Ln(III)
La(III)
Ce(III)
Pr(III)
K 2L n (4)
K 2L n (2) [13]
6.96
2
4
2.70 [12]
3.71±0.06
0.23 [12]
0.38±0.005
5.27 ± 0.05
5.74 ± 0.05
5.95 ± 0.05
6.05 ± 0.06
6.43 ± 0.06
6.47 ± 0.05
6.38 ± 0.06
6.72 ± 0.05
6.80 ± 0.06
6.81 ± 0.05
6.77 ± 0.07
6.71 ± 0.05
6.71 ± 0.06
6.64 ± 0.05
7.16
7.40
7.68
7.86
8.01
4.94
8.38
8.49
8.58
8.66
8.64
8.62
increases due to decrease of the ionic radius with rise
in Z [33].
Nd(III)
Sm(III)
Eu(III)
Gd(III)
Tb(III)
Dy(III)
Ho(III)
Er(III)
Tm(III)
Yb(III)
Lu(III)
The metal–extractant ratio in the extracted complexes
was determined by the equilibrium shift method. The
slopes of the dependences logD—log[L] for the extraction
of U(VI), Th(IV), and RE(III) were 1.67±0.05, 1.97±0.05,
and 1.94±0.05, respectively (Fig. 2). These data indicate
that compound 4 extracts uranium(VI) from nitric acid
solutions as a mixture of mono- and disolvates and that
Th(IV) and RE(III) are extracted as disolvates.According
to [20, 33], a solution of 2 in dichloroethane extracted
these ions in the form of complexes with the same
stoichiometry.
8.62
and 4 containing a phenylene fragment extracted RE(III)
ions more efficiently than their ethylene analogs 5 and
. However, replacement of the ethylene fragment in
molecule 7 by phenylene (compound 3) reduced D for
most RE(III) ions (Fig. 3).
Thus, the extraction of RE(III) with compound 4 from
nitric acid solutions can be described by Eq. (4).
6
Ln
Ln 3( + + 3NO– + 2L(o) ↔ LnL (NO ) , K 2L n
.
(4)
w)
3(w)
2
3 3(o)
The effective RE(III) extraction constants (K2Ln) were
calculated by the nonlinear least-squares method using
Eq. (5).
Table 3 compares the extraction abilities of compounds
–7 for U(VI) and Th(IV), as well as the separation
factors for thorium and uranium (βTh/U = D /D ). In
the extraction of Th(IV) from nitric acid solutions with
podands 2–4 and 5–7 under comparable conditions, the
DTh values decrease as the number of methylene units
n) increases. The extraction avility of 3 and 7 (n = 3)
for Th(IV) is even lower than that of 1. The extraction
ability for U(VI) increases in the series 5 < 6 < 7 in parallel
1
Th
U
DLn = K [NO ] γ [L] f –2
Ln
– 3
4
2
,
(5)
2
3
±
init
where γ is the activity coefficient of RE(III) nitrate [35],
±
f is a correction for extractant binding by nitric acid (f =
2
Ln
1
+ K a + K a ). The calculated values of K for
1 2 2
(
compound 4 are given in Table 2 together with those for
compound 2 (for comparison). It is seen that compound
is inferior to 2 in the extraction ability for RE(III) ions.
4
with n. The D values for compounds 2–4 change non-
U
The effect of the structure of phosphoryl-containing
podands 1–7 on the efficiency of extraction of RE(III)
ions from nitrate solutions was estimated by comparing
RE(III) partition coefficients determined under similar
conditions (Fig. 3). The data for compounds 1–3 and 5–7
were taken from our previous publication [14].Among the
examined compounds, phosphinate 1 extracted RE(III)
ions least efficiently, which is due to lower donor power
of the phosphoryl group in 1 than in 2–7. The D values
Ln
for compounds 2–4 containing a phenylene fragment
decrease in the series 2 > 4 > 3 in parallel with increase of
the length of the alkylene spacer between the phosphoryl
group and ether oxygen atom. Compounds 5–7 displayed
no clear relation between D and n: the highest extraction
ability was found for compound 6 (n = 2). Compounds 2
Fig. 3. Extraction of RE(III) from 4 M NH NO solutions with
Ln
4
3
0
.01 M solutions of compounds 1–7 in dichloroethane.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 90 No. 6 2020

1016
TURANOV et al.
Table 3. Uranium(VI) and thorium(IV) partition coefficients
The extraction of HTf N with compound 4 can be
described by Eq. (6), and the extraction constant is given
by Eq. (7).
2
in the extraction from 2 M HNO with 0.01 M solutions of
3
extractants 1–7 in dichloroethane
Extractant
log DTh
log DU
0.32
2.82
–1.42
1.40
1.25
βTh/U
0.70
95.5
0.02
2.40
5.50
2.40
0.02
+
–
H
+ Tf N + L(o) ↔ HTf NL ,
(6)
(7)
(
w)
2
(w)
2
(o)
–
1
2
3
4
5
6
7
[20]
[20]
[20]
0.47
+
K
= [HTf NL]/([L][H ][Tf N ]).
HTf N
2
2
2
0.84
0.33
1.02
0.51
0.75
0.85
The concentration constant for the extraction of
HTf N with compound 4 in dichloroethane was calculated
on the basis of the dependence of the Tf N partition
coefficient on the concentration of 4 in the organic
phase and the concentrations of Tf N and H in the
2
–
[20]
[20]
[20]
2
1.13
–0.82
–
+
2
+
aqueous phase. Preliminarily, we found that no Li or
–
Cl ions are transferred to the organic phase under the
monotonically with increase in n, and compound 4 (n =
) showed the highest extraction ability in this series.
The selectivity of separation of thorium and uranium
decreases with increase in n for compounds 2–4 and 5–7.
In the extraction with 3 and 7 (n = 3), the value of DU
was higher than DTh.
given conditions. The value KHTf2N = (6.31±0.5)×104
2
significantly exceeds the extraction constant of HNO for
the same compound (Table 1) due to considerably higher
hydrophobicity of Tf N compared to NO .
3
–
–
2
3
The synergistic effect in the extraction of RE(III) with
the system containing ionic liquid, S = D/D [where D and
0
The extractability of U(VI), Th(IV), and RE(III)
from nitric acid solutions with compound 4 significantly
increased in the presence of C mimTf N. This may be due
D are RE(III) partition coefficients in the presence and
in the absence of ionic liquid, respectively] decreases as
0
the HNO concentration increases. For example, in the
3
4
2
extraction of Eu(III), the S value decreases from 400 to
3.9 as [HNO ] increases from 0.1 to 3 M. The D —Z
to increase of hydrophobicity of the extracted complexes
–
–
3
Ln
where NO ions are replaced by hydrophobic Tf N ions
3
2
dependences for the extraction of RE(III) from nitric
acid solutions with solutions of 4 in ionic liquids and
in dichloroethane are somewhat different (Fig. 5). It is
seen that the S value in the extraction of RE(III) from
[
36]. The character of the logD —[HNO ] dependence
Ln 3
also changes in the presence of a ionic liquid in the organic
phase (Fig. 4). The reduction of DLn with rise in the
HNO concentration is related to the reduction of the free
3
3 M HNO decreases from 64 (La) to 1.2 (Er) and then
3
extractant concentration in the organic phase as a result
increases to 2.2 (Lu).
of interaction of 4 with both HNO and HTf N which
3
2
The stoichiometry of the complexes extracted in the
presence of ionic liquids is RE(III)–4 1 : 3 (Fig. 6), i.e.,
the solvation number is higher than in the extraction with
appears in the system as a result of appreciable transfer
+
–
of C mim and Tf N ions to the aqueous phase [37].
4
2
log [HNO3]
Fig. 4. Plots of (1) Lu(III), (2) Eu(III), and (3) La(III) partition
Fig. 5. Extraction of RE(III) from HNO3 solutions with 0.1 M
solutions of 4 in (1–3) ionic liquid and (4–6) dichloroethane;
Concentration of HNO3, M: (1, 6) 0.1, (2, 4) 1.0; and (3, 5) 3.0.
coefficients versus equilibrium HNO concentration in the
3
extraction with a 0.1 M solution of compound 4 in ionic liquid.
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EXTRACTION OF URANIUM(VI), THORIUM(IV), AND TRIVALENT RARE EARTHS
1017
compound 4 in dichloroethane (Fig. 2). This is related
–
to the low coordinating ability of Tf N ions [38] which
2
are likely to reside in the outer coordination sphere of the
extracted complex. In the absence of ionic liquids, RE(III)
ions are extracted with compounds 2 and 4 in the form
of coordinatively solvated nitrates LnL (NO ) where
2
3 3
3+
–
NO ions are involved in the coordination to Ln [19].
3
Our results showed that the extraction ability of
compound 4 for U(VI), Th(IV), and RE(III) ions is higher
than the extraction ability of its analog 6 containing a
conformationally flexible ethylene fragment instead of
phenylene as in 4. However, compound 4 is inferior
to analog 2 with only one methylene unit between the
P(O) group and ether oxygen atom. The efficiency of
extraction of RE(III) ions from nitric acid solutions with
log [L]
Fig. 6. Plots of (1) Lu(III), (2) Er(III), (3) Tb(III), (4) Eu(III),
and (5) La(III) partition coefficients versus concentration
of compound 4 in ionic liquid in the extraction from 0.1 M
{
[2-(2-diphenylphosphoryl)-4-ethylphenoxy]ethyl}-
HNO solutions.
3
diphenylphosphine oxide significantly increases in the
presence of a ionic liquid, 1-butyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)imide, in the organic phase.
C 72.15, 72.09; H 6.12, 6.07; P 8.23, 8.38. C H O P.
22
23
3
Calculated, %: C 72.12; H 6.33; P 8.45.
-(2-Chloroethoxy)-2-(diphenylphosphoryl)-4-
ethylbenzene (4b). Phosphorus pentachloride, 1.0 g
5.0 mmol), was added to a solution of 1.58 g (4.3 mmol)
of compound 4a in 15 mL of benzene. The mixture
was refluxed for 6 h and evap[orated under reduced
pressure, and the residue was treated with 15 mL of 10%
aqueous sodium hydrogen carbonate and extracted with
chloroform (3×30 mL). The combined extracts were
washed with dilute (1 : 2) aqueous HCl (3×30 mL) and
evaporated under reduced pressure, 15 mL of diethyl
ether was added to the residue, and the precipitate was
filtered off and dried. Yield 1.5 g (90.6%), mp 93–95°C
1
EXPERIMENTAL
The H and 31P NMR spectra were recorded on a
Bruker CXP-200 spectrometer. The melting points were
measured on a Boetius PHMK 05 melting point apparatus.
Silica gel L (particle size 100–150 μm) was used for
column chromatography.
1
(
2
-[2-(Diphenylphosphoryl)-4-ethylphenoxy]-
ethanol (4a). 4-Ethyl-2-(diphenylphosphoryl)phenol
39], 2.50 g (7.8 mmol), was dispersed in 20 mL
[
of anhydrous dioxane, 0.33 g (7.8 mmol) of a 55%
suspension of sodium hydride in mineral oil was added,
the mixture was refluxed for 0.5 h, and the solvent
was evaporated. The obtained sodium phenoxide
was transferred to an ampule, 0.65 g (8.0 mmol) of
1
(from hexane). H NMR spectrum (CDCl ), δ, ppm:
1.23 t (3H, CH CH , J = 7.6 Hz), 2.64 q (2H, CH CH ,
3
3
3
2
2
3
3
3
J = 7.6 Hz), 3.12 t (2H, CH CH Cl, J = 6.3 Hz), 3.96 t
2
2
3
2
-chloroethanol was added, and the ampu;e was sealed
(2H, CH CH Cl, J = 6.2 Hz), 6.79 m (1H, H
),
2
2
arom
31
and heated at 130°C for 26 h. After cooling, the ampule
was opened, the mixture was dissolved in 30 mL of
chloroform, and the solution was washed with dilute
7.28–7.56 m (7H, Harom), 7.71–7.79 m (5H, Harom). P
NMR spectrum (CDCl3): δP 27.6 ppm. Found, %: C 68.45,
68.59; H 5.72, 5.57; P8.23, 8.28. C22H22O3P. Calculated,
%: C 68.66; H 5.76; P 8.31.
(1 : 2) aqueous HCl (3×30 mL) and evaporated under
reduced pressure. The product was isolated by silica gel
column chromatography using chloroform as eluent.
Yield 1.67 g (58.6%), mp 122–124°C (from benzene–
2-(Diphenylphosphoryl)-1-[2-(diphenyl-
phosphoryl)ethoxy]-4-ethylbenzene (4). A solution of
1.3 g (5.0 mmol) of diphenylphosphinous acid in 10 mL
of hexamethyldisilazane was heated at 130°C for 1 h in a
stream of dry argon, and 1.53 g (4.0 mmol) of compound
4b was added. The mixture was heated at 220°C for
4 h, cooled, and treated with 10 mL of ethanol and 1 mL
of 30% hydrogen peroxide. The mixture was refluxed
for 1 h and evaporated under reduced pressure, and the
1
hexane). H NMR spectrum (CDCl ), δ, ppm: 1.10 t (3H,
3
3
3
CH CH , J = 7.6 Hz), 2.51 q (2H, CH CH , J = 7.4 Hz),
3
2
2
3
3
5
.62 m (2H, CH CH OH), 4.09 m (2H, CH CH OH),
2 2 2 2
.0 br.s (1H, CH OH), 6.9 m (2H, Harom), 7.35 m (1H,
2
H
arom), 7.52 m (6H, Harom), 7.72–7.79 m (4H, Harom).
31
P NMR spectrum (CDCl ): δ 30.86 ppm. Found, %:
3
P
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 90 No. 6 2020

1018
TURANOV et al.
residue was purified by silica gel column chromatography
ACKNOWLEDGMENTS
using chloroform and chloroform–propan-2-ol (100 : 1)
as eluents. Yield 1.7 g (77.3%), mp 185–186°C (from
The authors thank Sorbent-Tekhnologii Ltd. for
providing a sample of 1-butyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)imide.
1
benzene–hexane). H NMR spectrum (CDCl ), δ, ppm:
3
3
1
2
7
.78 t (CH CH , J = 7.6 Hz), 2.14 m [2H, CH P(O)],
.59 q (2H, CH CH , J = 7.6 Hz), 6.78 m (1H, Harom),
.33–7.78 m (22H, Harom). P NMR spectrum (CDCl ),
3
2
2
FUNDING
2
3
3
1
This study was performed in the framework of state tasks
to the Institute of Solid State Physics, Institute of Problems
of Microelectronics Technology and High-Purity Materials,
Frumkin Institute of Physical Chemistry and Electrochemistry,
and Institute of Physiologically Active Substances (Russian
Academy of Sciences) under partial financial support by the
Russian Foundation for Basic Research (project no. 18-29-
24069_mk).
3
δP, ppm: 27.79, 29.47. Found, %: C 74.02, 73.89; H 5.72,
5
.57; P11.03, 10.96. C H O P . Calculated, %: C 74.17;
34 32 3 2
H 5.86; P 11.25.
1
,2-Dichloroethane of chemically pure grade was
used without further purification. 1-butyl-3-methyl-
imidazolium bis(trifluoromethanesulfonyl)imide
(
C mimTf N) was synthesized and purified according to
4 2
CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
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