Synthesis of fluorinated malonamides and use in L/L extraction of f-elements

Article abstract of DOI:10.1016/j.tetlet.2013.09.031

Synthesis of new fluorinated tertiary malonamides (F-malonamides) was accomplished, and their liquid/liquid (L/L) extraction properties with f-elements were investigated. These molecules are fluorinated analogues of well known extractants used in several processes designed towards the treatment of nuclear wastes, and the efficient separation of lanthanides from minor actinides; however, the synthesis of F-malonamides deserved a modification of the general synthetic route commonly employed to prepare H-malonamides. Extraction of neodymium from various aqueous media into both fluorous and classical solvents was studied, which revealed an opposite trend between F-malonamides and H-malonamides: L/L extraction ability is very sensitive to the nitrogen atoms substitution pattern, and the most efficient F-malonamide is compound 3 (R₁ = Me), whereas the best H-malonamide is compound 5 (R₁ = Bu, DMDBTDMA).

Full text of DOI:10.1016/j.tetlet.2013.09.031

Tetrahedron Letters 54 (2013) 6271–6274
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Synthesis of fluorinated malonamides and use in L/L extraction
of f-elements
⇑
Marie-Claire Dul, Damien Bourgeois , Jérôme Maynadié, Daniel Meyer
Institut de Chimie Séparative de Marcoule, Laboratoire de Chimie et Physico-chimie des Actinides, UMR 5257, ICSM-LCPA, Bâtiment 426, BP 17171, 30207 Bagnols-sur-Cèze
cedex, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Synthesis of new fluorinated tertiary malonamides (F-malonamides) was accomplished, and their liquid/
liquid (L/L) extraction properties with f-elements were investigated. These molecules are fluorinated ana-
logues of well known extractants used in several processes designed towards the treatment of nuclear
wastes, and the efficient separation of lanthanides from minor actinides; however, the synthesis of
F-malonamides deserved a modification of the general synthetic route commonly employed to prepare
H-malonamides. Extraction of neodymium from various aqueous media into both fluorous and classical
solvents was studied, which revealed an opposite trend between F-malonamides and H-malonamides:
L/L extraction ability is very sensitive to the nitrogen atoms substitution pattern, and the most efficient
F-malonamide is compound 3 (R1 = Me), whereas the best H-malonamide is compound 5 (R1 = Bu,
DMDBTDMA).
Received 18 January 2013
Revised 9 September 2013
Accepted 11 September 2013
Available online 18 September 2013
Keywords:
Fluorinated compounds
Solvent extraction
f-Elements
Malonamide extractants
Lanthanides
Ó 2013 Elsevier Ltd. All rights reserved.
Introduction
several structural modifications led to the development of efficient
processes for the retreatment of nuclear wastes, aimed at the
Recovery of f-elements is a research subject of fast growing
importance, with the need for efficient recycling of several rare
earth metals, commonly used in optical, electronic, and magnetic
devices.1 Amongst the different envisioned processes, hydrometal-
lurgical ones are promising, since they are already well mastered
for (1) pure rare earth production from different natural ores,2
and (2) partitioning of nuclear fuel fission products.3 In both cases,
after digestion of solid matter with an acidic solution (hydrochlo-
ric, sulfuric or nitric), the metal cations are isolated from organic
phases after the liquid/liquid (L/L) extraction.4 Efficient extracting
systems, based on amphiphilic molecules, were developed, but
each system remains devoted to a particular input feed, with
limited balance between constituents in the aqueous layer. As a
remarkable example, whereas HDEHP (di-2-ethylhexylphosphoric
acid) used alone in a L/L extraction process enables efficient puri-
fication of heavy lanthanides, separation factors are too low to pur-
ify light lanthanides and actinides mixtures with this sole
molecule.5 All these metals present at the +III oxidation state, are
hard cations, and differ only in their radii, as revealed by the lan-
thanide contraction.6
lanthanide-actinide separation.8 The introduction of various long
hydrocarbon chains enables fine tuning of the hydrophobic proper-
ties of the molecules, responsible for the structuration of the
organic layer, one of the key parameters for selective and efficient
L/L extraction.9 The ability to coordinate metal ions, and especially
f-elements, results from the thermodynamic stabilization induced
by the chelate effect of the bidentate coordination mode. The best
candidate molecules today are the N,N0-tetrasubstituted-2-alkyl-
ated malonamides DMDBTDMA (R1 = n-C4H9 and R = n-C14H29
)
and DMDOHEMA (R1 = n-C8H17 and R = n-C2H4OC6H13) depicted
in Figure 1.10 They were developed to ameliorate the HDEHP
extraction, and take profit of the fact that actinides(III) such as
Am and Cm are a little softer than their lanthanide counterparts,
with a larger 5f orbital enabling f-electrons to participate in the
chemical bonding.11 They represent today the benchmark in f-ele-
ments L/L extraction, and are also used in other separation tech-
niques e.g., extraction chromatography,12 or hybrid functional
materials for solid–liquid extraction such as silica13 and magnetic
particles.14
Interestingly, as fluorous chemistry15 proved its efficiency in
various fields including L/L extraction and purification of organic
and inorganic compounds,16 to our knowledge only one publica-
tion deals with the adaptation of this technology for the separation
of f-elements, employing a polypyridine chelating agent,17 and
even very few with the extraction of d-elements.18 Interests of
fluorous techniques are multiple: extraction kinetics may be
Malonamide ligands, with general formula (MeR1NCO)2CHR, are
neutral amphiphilic molecules which have proved their potency
for the extraction of f-elements since the early 60 s.7 Later on,
⇑
Corresponding author. Tel.: +33 (0)4 66 33 94 92; fax: +33 (0)4 66 79 76 11.
E-mail address: damien.bourgeois@cea.fr (D. Bourgeois).
0040-4039/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2013.09.031

6272
M.-C. Dul et al. / Tetrahedron Letters 54 (2013) 6271–6274
Thus, the amide-formation step and the alkylation had to be
inverted (Route B, Scheme 1). To our knowledge, this route was
only used for the preparation of secondary malonamides, where
N-alkylation is expected when following Route A.23 Required
substituted diethyl malonates 7–9 were obtained according to a
reported procedure:24 starting from diethyl malonate which pos-
sesses an enhanced reactive methylene compared to tertiary malo-
namides, monoalkylation with various alkyl bromides or iodides,
including perfluoroalkyl iodides, is very efficient, with yields high-
er than 80% after purification with bulb-to-bulb distillation on a
multigram scale. Then, direct di-amide formation from these di-es-
ters and the corresponding secondary amine was attempted in the
case of ester 7, but only selective decarboxylation and formation of
the mono-amide 10 were observed (Scheme 2). Use of Lewis acids
such as BF3ꢀOEt2 did not change the outcome of this reaction.
The only efficient way to obtain the desired substituted F-malo-
namides consisted in (1) hydrolysing the di-ester into the corre-
sponding di-acid, and (2) activating it into the di-acid chloride,
then reacting the latter in situ with the suitable amine (Scheme 2).
The first step does not deserve any other purification than extrac-
tion from aqueous layer, and drying in vacuo, so that only one final
purification with chromatography on silica gel is necessary, as
already performed on large scale with Route A (see Ref. 22). Thus,
the desired F-malonamides were synthesized with yields ranging
from 55 to 70% from di-esters 7–9, depending on the chosen amine
(bulky secondary amines leading to lower yields), and the F-chain
(Scheme 2 and Table 1).25
These compounds are either waxy solids or oils. Although they
clearly show supramolecular organization (birefringent behaviour
during observation under polarized light optical microscope), their
differential thermal analysis (DTA) curves do not show other tran-
sition than melting/solidification. When R1 is a butyl group, the 1H
and 13C NMR spectra exhibits up to four sets of signals which are
characteristic of ZZ, EZ and EE isomers due to the cis/trans confor-
mations of the tertiary amide bonds, as previously observed in
the hydrocarbonated compound 1.26 Thus, in CDCl3, the 1H NMR
spectra of compounds 5, 15 and 17 reveal four singlets for the
N-CH3 signal, and complicate multiplets for some other signals.
In the 13C NMR spectra, four distinct different peaks appear for
the C@O, NCH3 and NH2 signals. Even the methyl group at the
end of the butyl chain leads to several signals with different chem-
ical shifts in both types of spectra. 1H NMR analysis of compound 5
was also performed in toluene-d8: at 298 K, a clear separation of
each triplet characteristic of the malonic proton is obtained, and
heating to 378 K leads to a clean transition into a unique signal
for this proton, as well as a clean whole spectrum, guarantee of
the purity of the prepared compound (see Supplementary data).
These isomers are not found in symmetrical compounds 3, 14
and 16 where R1 = Me.
O
O
O
O
O O
Me
Me
Me
Me
Me Me
N
N
N
N
N
N
R1
Rf
R1
O
CF3
Rf =
F F
n
DMDOHEMA
This work
DMDBTDMA (1)
Figure 1. Classical malonamide extractants used for the selective separation of f-
elements: N,N0-dimethyl-N,N0-dibutyl-2-tetradecyl malonamide (DMDBTDMA, 1);
N-N0-dimethyl-N,N0-dioctyl-2-hexaethyl malonamide (DMDOHEMA); and targeted
fluorinated malonamides.
improved, as dynamic surface tension measurements proved a bet-
ter affinity of F-surfactants for interfaces.19 Also, the chemical sta-
bility of the C–F bond makes F-organic derivatives very stable,
including towards radiation.20 Then, as F-compounds are much
less soluble in water than their H-analogues, leaching of the
extracting molecule into the aqueous layer should be lower. Final-
ly, ‘3-phases’ (aqueous/organic/fluorous) system and temperature
dependent phase separation are possible and offer more opportu-
nities in L/L extraction.21
It is the purpose of this Letter to report the preparation of fluo-
rinated malonamides (F-malonamides), directly inspired from
DMDBTDMA (1, Fig. 1), and our first results regarding the issues
related to L/L extraction with these compounds.
Synthesis
The synthesis of all malonamides employed for nuclear waste
treatments relies on the monoalkylation of the activated methy-
lene of suitable N,N0-tetrasubstituted malonamides (Route A,
Scheme 1). As the N-substituents become bulkier, yields of the
alkylation drop severely. And then, as the final products are oily
compounds which tend to drag on silica gel during purification
with flash chromatography, they become difficult to obtain in de-
cent yield and purity, especially on a large scale.22
When adapting this classical route to perfluorinated alkylating
agents, such as 1H,1H,2H,2H-perfluorooctyl iodide, it was only pos-
sible to obtain the target compound 3 starting from N,N0-tetra-
methyl malonamide 2, thanks to the low steric effect on the
amide groups, albeit with a poor yield (12%, Scheme 2). All other
substitution patterns resulted in the desired compound in trace
amount only.
O
O
Liquid/liquid extraction
O
O
Me
Me
N
N
Route A
Cl
Cl
R1
R1
Our first surprise was the poor solubility of prepared F-malona-
mides in common fluorinated solvents such as perfluorohexane or
perfluorotoluene. Solubility tests proved that compounds 5, 15
and 17 (R1 = Bu) are not miscible with perfluorohexane, whereas
solubility of compounds 3, 14 and 16 (R1 = Me) in the same solvent
increases with the length of the fluorous chain: it is estimated to be
<0.1 M for 16 (C4F9 chain), ca. 0.3 M for 14 (C6F13 chain) and >1 M for
3 (C8F17 chain). These results demonstrate the need for a minimum
F/H ratio to ensure compatibility of F-malonamides with common
O
O
Me
Me
R1
N
N
R1
Rf
Targeted
malonamides
O
O
O O
EtO
Route B
OEt
EtO
OEt
Rf
Scheme 1. Envisioned synthesis of hydrocarbonated and fluorinated malonamide-
The intermediate acids 11–13 can also be easily isolated as their potassium salts
after concentration of crude saponification mixture in vacuo, followed by washing
with ethanol and diethylether.
based extractants: Route
diethylmalonate.
A starting from malonyl chloride, Route B from

M.-C. Dul et al. / Tetrahedron Letters 54 (2013) 6271–6274
6273
Route A
NaH, THF
O
O
O
O
Rf = n-C8F17
R = n-C14H29
RfCH2CH2I
Me
R1
Me
Me
R1
Me
N
N
N
N
3
5
6
1
R1 = Me, 12%
R1 = Me, 34%
R1
R or Rf
R1
R1 = nBu, < 5%
(one step)
R1 = nBu, 30%
(one step)
or RCH2CH2I
2 R1 = Me
R1 = nBu
4
Route B
NaH, THF
RfCH2CH2I
O
O
O
O
O
MeR1NH, Δ
Me
Rf
EtO
OEt
EtO
OEt
N
R1
Rf = n-C8F17
n-C6F13
7
8
9
10
Rf = n-C8F17
Rf
n-C4F9
KOH, EtOH
Then aq. HCl
1) (COCl)2, DCM,
O
O
O
O
cat. DMF
Me
Me
R1
See Table 1
for details
HO
OH
N
N
Rf = n-C8F17 11
n-C6F13 12
2) MeR1NH, NEt3
R1
Rf
Rf
55%-70% from 7-9
n-C4F9
13
Scheme 2. Synthesis of targeted compounds.
Table 1
F-malonamides synthesized via Route B (Scheme 2)
Table 2
Proportion of Nd(III) in the organic phase after L/L extraction with H- (1 and 6) and F-
(3 and 5) malonamides,a and corresponding distribution coefficients Db
Product
Substituent groups
1 = CH3
Aspect
Yield from di-esters 7–9 (%)
Entry
1
Extractant
Salt
DCM
n-decane
Perfluorohexane
—
3
R
Waxy solid
68
Rf = n-C8F17
R1 = n-C4H9
Rf = n-C8F17
R1 = CH3
Rf = n-C6F13
R1 = n-C4H9
Rf = n-C6F13
R1 = CH3
1
Nitrate
10%
D = 0.1
71%
32%
D = 0.5
80%
D = 4
(2b%)
(0b%)
5
14
15
16
17
Yellow oil
Waxy solid
Yellow oil
Waxy solid
Yellow oil
55
63
58
70
56
2
1
Triflate
—
D = 2.5
(3b%)
8c%
3
4
6
6
Nitrate
Triflate
—
—
D = 0.1c
(3b%)
(0b%)
11%
5
6
7
5
5
3
Nitrate
Triflate
Nitrate
—
—
—
—
—
70%
D = 2.3
68%
D = 2.1
Rf = n-C4F9
R1 = n-C4H9
Rf = n-C4F9
D = 0.1
14%
D = 0.15
8
3
Triflate
—
F-solvents. As expected, F-malonamides were also not soluble in
aliphatic solvents generally used for malonamide-based L/L extrac-
tion processes, such as n-decane. It eventually turned out that all
compounds are completely soluble in dichloromethane (DCM), so
first L/L trials were carried out with this solvent. We focused on
compounds bearing a C8F17 chain, as F-malonamide 3 is the only
compound well soluble in perfluorohexane.
a
All concentrations were determined by ICP-AES and are corrected from residual
extraction with solvent alone.
b
Values between brackets are too low to be considered with confidence and used
to derive D.
c
Third phase also present.
The aptitude of the synthesized malonamides to extract a
lanthanide cation into an organic phase was evaluated on neodym-
ium(III) salts. L/L extraction tests were performed in conditions
designed after the analysis of the literature results with hydrocar-
bonated malonamide 1 in alkanes: In order to compare the differ-
ent extraction behaviours the experimental conditions were
chosen where the distribution coefficient (D, the ratio of metal
concentrations in organic and aqueous phases) of neodymium dur-
ing extraction with this system is close to 1. Thus the concentration
of the extracting molecule was fixed to 0.5 M in the appropriate
solvent, and the acid concentration of the aqueous layer to 1 M,
with a 0.05 M initial concentration of Nd(III). In these conditions,
about 30% of Nd is extracted (D = 0.42).27 The same aqueous layer
was then used for all systems, either as a nitrate salt in aqueous
nitric acid, or as a triflate salt in diluted aqueous triflic acid. Nitric
acid is commonly used during the reprocessing of nuclear wastes,
and triflate salts are the weakly-coordinating hydrophobic coun-
ter-ions regularly employed for organometallic catalysis.
All results are summarized in Table 2. The determined concen-
trations were corrected from residual extraction with the solvent
alone, which range from 2 to 6% depending on the solvent and
the metal salt. Distribution coefficients were not determined for
low extraction values (results presented between brackets)
because of a too low precision of the amount taken into the organic
layer by the extractant. The result of the reference system
(DMDBTDMA (1) in n-decane, entry 1) is in full agreement with
the literature detailed above. It is interesting to notice that the
change from n-decane to DCM does not modify consequently the
extraction properties of 1 (entry 1). Modification of the aqueous
phase salt from nitrate to triflate leads to higher quantities of
extracted Nd(III) salts in both solvents, probably due to the higher
hydrophobicity of the triflate salt (entry 2). On the other hand, the
extracting ability of malonamide 6 (R1 = Me, entry 3) is much lower
compared to 1. Although the behaviour of compound 6 in L/L
extraction was not reported to our knowledge, it is possible
that this compound was also screened during malonamide

6274
M.-C. Dul et al. / Tetrahedron Letters 54 (2013) 6271–6274
2. Gupta, C. K.; Krishnamurthy, N. Extractive Metallurgy of Rare Earths; CRC Press,
2004.
3. (a) Tachimori, S.; Morita, J. Overview Of Solvent Extraction For Reprocessing, In
Ion Exchange And Solvent Extraction In Bruce, A., Moyer, Eds.; CRC Press, 2010;
pp 1–64. Vol. 19; (b) Mathur, J. N.; Murali, M. S.; Nash, K. L. Solvent Extr. Ion
Exch. 2001, 19(3), 357–390.
structure-activity studies, and discarded because of poor efficiency.
This compound may be more water soluble and leach into the
aqueous phase. We link this to the formation of a gel-like third
phase during the extraction of triflate salts (Entry 4).
With F-malonamide 5 (R1 = Bu) in DCM, extraction of Nd is
very low, whatever the counter ion (entries 5 and 6). In the case
of triflic medium, the amount of Nd in the organic phase was
even below the detection limit of the analytical method (ICP-
AES). This dramatic change has no explanation yet, and will be
the object of further comprehensive studies. In the case of
F-malonamide 3 (R1 = Me), the quantities of extracted Nd(III)
salts in perfluorohexane are very high, whatever the counter-
ion (entries 7 and 8), and comparable to the reference system
(entries 1 and 2). Thus, it turned out that the H-malonamide 1
(R1 = Bu) remains the best extractant system in alcanes, whereas
F-malonamide 3 (R1 = Me) is the best extractant system in fluori-
nated solvent, and with comparable efficiency. Further studies
will be performed to take profit of these results towards the sep-
aration of the f-elements: The present data demonstrate a clear
capacity for F-malonamides to extract lanthanide salts with
nitrate as well as triflate counter-ions.
4. Rydberg, J.; Cox, M.; Musikas, C.; Choppin, G. R. Solvent Extraction Principles And
Practice; Marcel Dekker, Inc: New york and Basel, 2004. 2nd ed..
5. Gannaz, B.; Chiarizia, R.; Antonio, M. R.; Hill, C.; Cote, G. Solvent Extr. Ion Exch.
2007, 25(3), 313–3370.
6. Shannon, R. D. Acta Crystallogr. Sect. A 1976, 32, 751–767.
7. Siddall, T. H. J. Inorg. Nucl. Chem. 1967, 25, 883–892.
8. Cuillerdier, C.; Hoel, P.; Musikas, C.; Nigond, L. Eur. Pat. Appl. EP 505277 A1
19920923, 1992.
9. Berthon, L.; Testard, F.; Martinet, L.; Zemb, T.; Madic, C. C. R. Chim. 2010, 13,
1326–1334.
10. Manchanda, V. K.; Pathak, P. N. Sep. Purif. Technol. 2004, 35, 85–103.
11. (a) Seaborg, G. T. Radiochim. Acta 1993, 61(3–4), 115–122; (b) Nagame, Y.;
Hirata, M. Radiochim. Acta 2011, 99(7–8), 377–393.
12. Mohapatra, P. K.; Sriram, S.; Manchanda, V. K.; Badheka, L. P. Sep. Sci. Technol.
2000, 35(1), 39–55.
13. Broudic, J.-C.; Conocar, O.; Moreau, J. E.; Meyer, D.; Wong Chi Man, M. J. Mater.
Chem. 1999, 9(10), 2283–2285.
14. Shabu, B. S.; Reddy, M. L. P.; Prabhu, D. R.; Kanekar, A. S.; Manchanda, V. K.
Radiochim. Acta 2006, 94(5), 267–273.
15. Horváth, I. T.; Rábai, J. Science 1994, 266, 72–75.
16. (a) Gladysz, J. A.; Curran, D. P.; Horváth, I. T. Handbook of Fluorous Chemistry;
Wiley-VCH: Weinheim, 2004. pp. 1–595; (b) O’Neal, K. L.; Zhang, H.; Yang, Y.;
Hong, L.; Lu, D.; Weber, S. G. J. Chromatogr. A 2010, 1217, 2287–2295; (c)
Barthel-Rosa, L. P.; Gladysz, J. A. Coord. Chem. Rev. 1999, 190–192, 587–605.
17. Kida, T.; Inaba, Y.; Watanabe, W.; Nakajima, Y.; Fukuoka, S.; Takeshita, K.; Mori,
A. Chem. Lett. 2010, 39, 774–776.
Conclusions
In summary, we have reported here the efficient synthesis of
fluorinated malonamide-based ligands for the extraction of lantha-
nides. This new class of compounds was synthesized in good yields
on multigram scale, and their L/L extracting abilities were studied
on neodymium salts. We proved that the stabilization of Nd(III)
salts in F-solvents does not require the fluorophilic triflate coun-
ter-ion, and is rather the result of a careful design of the extracting
molecule. F-malonamide 3 (R1 = Me) in perfluorohexane shows
comparable efficiency to H-malonamide 1 (R1 = Bu) in decane.
Others systems (substituents and extraction conditions) are now
considered to improve the extraction properties and the separation
of various f-elements. Also, the hydrophilic–lipophilic–fluorophilic
balance will be the object of detailed studies. Direct applications of
this technique deal with the preconcentration of f-elements for
analytical purposes, important in the frame of radionuclides anal-
ysis. Moreover, the stabilization of a lanthanide salt into a fluorous
layer may find applications in the recovery of Lewis acid cata-
lysts,28 and all the results will be reported in due course.
18. (a) Nakashima, K.; Maruyama, T.; Kubota, F.; Goto, M. Anal. Sci. 2009, 25, 77–
82; (b) Bhattacharyya, P.; Croxtall, B.; Fawcett, J.; Fawcett, J.; Gudmunsen, D.;
Hope, E. G.; Kemmitt, R. D. W.; Paige, D. R.; Russell, D. R.; Stuart, A. M.; Wood,
D. R. W. J. Fluorine Chem. 2000, 101, 247–255.
19. Yoshimura, T.; Ohno, A.; Esumi, K. Langmuir 2006, 22, 4643–4648.
20. Faucitano, A.; Buttafava, A.; Karolczak, S.; Guarda, P. A.; Marchionni, G. J.
Fluorine Chem. 2004, 125, 221–241.
21. Chu, Q.; Yu, M. S.; Curran, D. P. Tetrahedron 2007, 63, 9890–9895.
22. Product is generally provided by panchim, but needs re-purification by
chromatography on silica gel. See Berthon, L.; Martinet, L.; Testard, F.; Madic,
C.; Zemb, T. Solvent Extr. Ion Exch. 2007, 25, 545–576. Noteworthy, no report of
the yield for the synthesis of 1 was reported in literature.
23. Hirose, T.; Hiratani, K.; Kasuga, K.; Saito, K.; Koike, T.; Kimura, E.; Nagawa, Y.;
Nakanishi, H. J. Chem. Soc., Dalton Trans. 1992, 2679–2683.
24. Trabelsi, H.; Szönyi, F.; Geribaldi, S. J. Fluorine Chem. 2001, 107, 177–181.
25. Typical procedure for the preparation of F-malonamide 5 via Route B: To a
solution of di-ester 7 (9.70 g, 16 mmol) in ethanol (30 mL) was added KOH
(1.80 g, 2.0 equiv) dissolved in water (5 mL), and the resulting mixture was
heated under reflux for 4 h. After reduction of the volume in vacuo, aqueous
HCl (4 M) was added dropwise under vigorous stirring in an ice-water bath
until pH got close to 7 and a cream white solid formed. The solid was filtered,
washed with water, ethanol, then diethyl ether and dried in vacuo. It was then
suspended into DCM (10 mL) and oxalyl chloride (3.4 mL, 2.5 equiv) was added
slowly (30 min) in an ice-water bath under argon, followed by a drop of dry
DMF. The mixture was then allowed to go back to room temperature, and
turned clear. Stirring was pursued for 1 h30. The resulting orange solution was
then added slowly into a flask under argon containing triethylamine (4.5 mL,
2.5 equiv) and N,N0-methylbutyl amine in excess (19.0 mL, 10 equiv) in DCM
(50 mL) and heated under reflux for 6 h. The white solid formed was removed
with filtration, and the organic solution was washed with water (2 ꢁ 50 mL),
brine (20 mL) and concentrated in vacuo. Purification on silica gel (40 g) with
elution of an ethylacetate/cyclohexane mixture (80:20 in volume) led to
compound 5 as yellow oil (6.05g, 55% yield). Data for 5 (C23F17H29N2O2,
Acknowledgments
We thank the Marcoule Institute for Separative Chemistry for
facilities and the CNRS and the CEA for financial support.
Dr. M.-C. Dul is grateful to the RBPCH program of the CEA for her
postdoctoral fellowship.
688.47 g molꢂ1) IR (ATR)
m
(cmꢂ1): 2962, 2935, 1638 (CO amide), 1238, 1200,
1145, 1110; 1H NMR (400 MHz, CDCl3) d(ppm): 3.61–3.68 (m, 1H, NCH2) 3.35–
3.27 (m, 3H, NCH2), 3.26–3.14 (m, 1H, COCHCO), 2.96, 2.95, 2.92, 2.91 (4s, 6H,
NCH3), 2.26–2.10 (m, 4H, CH(CH2)2), 1.53–1.45 (m, 4H, CH2 of
NCH2CH2CH2CH3), 1.33–1.23 (m, 4H, CH2 of NCH2CH2CH2CH3), 0.94–0.88 (m,
6H, NCH2CH2CH2CH3); 19F NMR (376.3 MHz, CDCl3) d(ppm): ꢂ80.8 (s, 3F, CF3),
ꢂ115.0 (m, 2F, CF2), ꢂ121.8 (s, 2F, CF2), ꢂ122.0 (s, 6F, 3 CF2), ꢂ122.8 (s, 2F, CF2),
ꢂ123.4 (s, 2F, CF2), ꢂ126.2 (s, 2F, CF2); 13C NMR (100.6 MHz, CDCl3) d(ppm):
168.4, 168.3, 168.2, 168.2 (CO), 121.6–112.8 (m, CF3), 113.8–105.5 (m, 7 CF2),
49.4 (COCHCO), 48.3, 48.2, 48.2, 48.0 (NCH2), 35.0, 35.0, 33.5, 33.5 (NCH3), 30.4,
30.3, 29.0 (NCH2CH2CH2CH3), 29.0–28.5, 20.6–19.8 (2m, CH(CH2)2(CF2)7CF3),
20.0 (NCH2CH2CH2CH3), 13.7, 13.6 (NCH2CH2CH2CH3); HRMS (Q-TOF ES+):
Calc. for C23H30N2O2F17 689.2036 [MH+], found 689.2005.
Supplementary data
Supplementary data (characterization for all new compunds,
representative IR and NMR spectra and toluene-d8 temperature
dependence 1H NMR spectra of 5.) associated with this article
can be found, in the online version, at http://dx.doi.org/10.1016/
j.tetlet.2013.09.031.
References and notes
26. Lefrançois, L.; Hébrant, M.; Tondre, C.; Delpuech, J.-J.; Berthon, C.; Madic, C. J.
Chem. Soc., Perkin Trans. 2 1999, 1149–1158.
27. L. Nigond, Ph.D. Thesis, Université Blaise Pascal, Clermont Ferrand, 1992, CEA-
R-5610.
28. (a) Yi, W.-B.; Cai, C. J. Fluorine Chem. 2005, 126, 1553–1558; (b) Juliette, J. J. J.;
Rutherford, D.; Horváth, I. T.; Gladysz, J. A. J. Am. Chem. Soc. 1999, 121, 2696–
2704.
1. (a) Goonan, T. G.; Rare earth elements
– End use and recyclability: US
Geological Survey Scientific Investigations Report 2011-5094, 15 p. available
only at http://pubs.usgs.gov/sir/2011/5094/.; (b) Wang, L.; Huang, X.; Yu, Y.;
Cui, D.; Zhang, G. Hydrometallurgy 2010, 101, 41–47; (c) Innoncenzi, V.; Vegliò,
F. J. Power Sources 2012, 211, 184–191; (d) Yang, H.; Wang, W.; Zhang, D.; Deng,
Y.; Cui, H.; Chen, J.; Li, D. Ind. Eng. Chem. Res. 2010, 49, 11645–11651.