Synthesis and extraction properties of first representatives of 2-(phosphorylamido)-substituted 1,8-naphthyridines

Full text of DOI:10.1134/S0012500809040053

ISSN 0012-5008, Doklady Chemistry, 2009, Vol. 425, Part 2, pp. 84–87. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © P.S. Lemport, E.I. Goryunov, I.B. Goryunova, A.A. Letyushov, A.M. Safiulina, I.G. Tananaev, E.E. Nifant’ev, B.F. Myasoedov, 2009, published in Doklady
Akademii Nauk, 2009, Vol. 425, No. 6, pp. 773–776.
CHEMISTRY
Synthesis and Extraction Properties
of First Representatives
of 2-(Phosphorylamido)-Substituted 1,8-Naphthyridines
P. S. Lemporta, E. I. Goryunova, I. B. Goryunovaa, A. A. Letyushovb,
A. M. Safiulinab, Corresponding Member of the RAS I. G. Tananaevb,
Corresponding Member of the RAS E. E. Nifant’eva, and Academician B. F. Myasoedovb
Received October 28, 2008
DOI: 10.1134/S0012500809040053
Liquid radioactive waste, which is formed in large
amounts in the process of spent fuel treatment, is a seri-
ous environmental hazard since it contains consider-
able amounts of long-lived radionuclides, mainly radio-
active isotopes of f elements, actinides and lanthanides
[1]. One of the most promising methods of liquid waste
treatment is extraction with the use of different types of
organic and organoelement compounds as extractants.
Organoelement extractants of greatest interest are neu-
tral organophosphorus ligands, first of all, bidentate
ones, capable of efficiently extracting tetra- and
hexavalent actinides from acid media. Unfortunately,
these ligands are, as a rule, considerably less effi-
cient in extraction of trivalent actinides and lan-
thanides [2]. At the same time, it was shown that
trivalent actinides (for example, americium and
curium) can be efficiently extracted from acid media by
means of various polydentate nitrogen-containing hetero-
cycles, such as tripyridyltriazines, terpyridines, bis(benz-
imidazolyl)pyridines, bis(benzothiazolyl)pyridines, and
especially polyalkyl-substituted 2,6-bis(1,2,4-triazin-
3-yl)pyridines [3–5].
As such a heterocyclic moiety, 1,8-naphthyridine
deserves special attention. In its molecule, the
arrangement of the nitrogen atoms is optimal for che-
lation of various metal cations, including lanthanide
ions [6, 7].
5
4
6
7
3
2
8
1
N
N
Mz+
In this case, the potentially best conditions for
complex formation can be achieved when a phospho-
ryl-containing substituent is introduced into the 2-
position of the naphthyridine ring and especially
when an imide bridge is used as the linker between
the ligating fragments (the heterocycle and the phos-
phoryl group). The presence of this bridge not only
optimizes the distance between the endocyclic nitro-
gen atoms and the phosphorus atom but also ensures
delocalization of the electron system of the chelating
It might be expected that design of neutral organo-
phosphorus extractants with molecules containing
polynitrogen heterocyclic moieties would make it pos- center.
sible to extend the field of application of the resulting
hybrid structures and to find compounds with a unique
combination of useful properties.
In this work, we synthesized for the first time a
series of various 2-(phosphorylamido)-substituted 1,8-
naphthyridines and demonstrated that compounds of
this type can selectively extract lanthanides from car-
bonate media.
a Nesmeyanov Institute of Organoelement Compounds,
Russian Academy of Sciences, ul. Vavilova 28,
Moscow, 119991 Russia
b Frumkin Institute of Physical Chemistry and
Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
These compounds were obtained by direct phospho-
rylation of 2-amino-1,8-naphthyridines with phospho-
ryl chlorides (Scheme 1).
84

SYNTHESIS AND EXTRACTION PROPERTIES OF FIRST REPRESENTATIVES
CH3
85
O
P R
R'
CH3
H3C
N
N
IIIa–h
N
H
Py
O
Et3N
+
P R
R'
Cl
H3C
N
N
NH2
CHCl3
Et3N
CH3
N
I
IIa–j
O
P R
R'
H3C
N
N
H
IIIa–j
II, III: a R = R' = Ph; b R = R' = PhO; c R = R' = o-MeC6H4O; d R = R' = m-MeC6H4O; e R = R' = p-MeC6H4O;
f R = Ph, R' = Me; g R = Me, R' = PhO; h R = Ph, R' = EtO; i R = Me, R' = EtO; j R = R' = EtO.
Scheme 1.
by elemental analysis data and 31ê{1H} NMR (Table 1).
In all cases, the 31ê{1H} NMR spectra show a singlet in
the region typical of the corresponding environment of
the phosphorus atom.
2-Amino-5,7-dimethyl-1,8-naphthyridine (I), which is
readily synthesized from inexpensive commercially
available reagents, was used as the initial amino-substi-
tuted naphthyridine. Various phosphoric, phosphonic,
and phosphinic monochlorides IIa–IIj were used as
phosphorylating agents, so that the nature of the sub-
stituents at the ligating phosphoryl group varies in a
wide range.
Taking into account the fact that initial heterocyclic
amine I is poorly soluble in most organic solvents, 5,7-
dimethyl-2-(phosphorylamido)-1,8-naphthyridines III
were first synthesized by refluxing a pyridine solution
of amine I with a phosphorylating agent in the presence
of triethylamine as the hydrogen chloride acceptor,
which is considerably more basic than pyridine
(method A). However, it turned out that, while phos-
phorylamides IIIa–IIIg are obtained in rather high
yields (71–83%) by this method (Table 1), the yield of
IIIh sharply decreases (to 45%), and phosphoramides
IIIi and IIIj are not synthesized at all because of the
destruction of the corresponding initial acid chlorides
II under the conditions used.
Therefore, we developed an alternative variant of
synthesis of 5,7-dimethyl-2-(phosphorylamido)-1,8-
naphthyridines under much milder conditions. The
method consists in the reaction of chlorides IIa–IIj
under heating with a suspension of aminonaphthyridine
I in chloroform in the presence of triethylamine
(method B). Under these conditions, we succeeded in
synthesizing phosphoramides IIIi and IIIj, and the
yields of compounds IIIa–IIIh were higher (in the case
of IIIh, considerably higher) than those afforded by
method A (Table 1).
The next step of the work was to study the possibil-
ities of using the synthesized 2-(phosphorylamido)-
subsituted 1,8-naphthyridines for extraction of 4f and 5f
elements from nitric acid and carbonate media. The
study was performed for 5,7-dimethyl-2-(diphe-
nylphosphinamido)-1,8-naphthyridine IIIa and La(III),
Nd(III), Th(IV), and U(VI) as an example. We found
that this phosphorus–nitrogen ligand taken in concen-
tration of 0.01 mol/L in chloroform selectively extracts
lanthanides(III) from carbonate media, whereas the dis-
tribution ratios in nitric acid media are low for the met-
als tested (Table 2).
Taking into account that carbonate solutions are not
typical media for the extraction of f elements by neutral
organophosphorus compounds (both mono- and
polydentate), our findings concerning the extraction
with 2-(phosphorylamido)-substituted 1,8-naphthy-
ridines allow us to draw the conclusion that these
hybrid extractants have unique properties.
It is worth noting that, according to preliminary
data, phosphoryl-containing 1,8-naphthyridines III do
act as tridentate ligands in complexation of lanthanide
cations. Both nitrogen atoms of the heterocycle and the
phosphoryl oxygen atom are involved in the coordina-
tion of the metal [8].
EXPERIMENTAL
The 31ê{1H} NMR spectra of solutions in CDCl3
were recorded at 298 K on a Bruker Avance-400 spec-
trometer operating at 161.98 MHz with 85% H3PO4 as
All synthesized 5,7-dimethyl-2-(phosphorylamido)-
1,8-naphthyridines IIIa–IIIj are white or light yellow
air-stable solids readily soluble in dimethylformamide,
dimethyl sulfoxide, pyridine, benzene, and chloroform, the external reference. Standard tubes 5 mm in diameter
poorly soluble in hexane and ether, and insoluble in were used. The concentration of solutions was
water. The structure of the compounds was confirmed 0.02 mol/L. Elemental analysis was carried out in the
DOKLADY CHEMISTRY Vol. 425 Part 2 2009

86
LEMPORT et al.
Table 1. Yields and properties of 5,7-dimethyl-2-(phosphorylamido)-1,8-naphthyridines IIIa–IIIj
Found/calculated, %
31P{1H}
NMR,
δ, ppm, s
Yield*,
%
Empirical
formula
Compound
Tm, °C
C
H
N
P
70.85
------------
70.77
5.29
---------
5.40
11.30
------------
11.25
8.45
---------
8.30
IIIa
IIIb
IIIc
IIId
IIIe
IIIf
IIIg
IIIh
IIIi
86 (78)
80 (71)
82 (80)
80 (74)
84 (83)
83 (72)
79 (74)
78 (45)
82 (0)
191–193
67–69
C22H20N3OP
C22H20N3O3P
C24H24N3O3P
C24H24N3O3P
C24H24N3O3P
C17H18N3OP
C17H18N3O2P
C18H20N3O2P
C13H18N3O2P
C14H20N3O3P
16.8
–3.0
–2.7
–3.5
–3.2
30.1
29.4
18.4
29.5
1.8
65.18
------------
65.18
5.03
---------
4.97
10.21
------------
10.37
7.46
---------
7.64
66.37
------------
66.50
5.49
---------
5.58
9.70
---------
9.69
7.10
---------
7.15
138–140
97–99
66.61
------------
66.50
5.52
---------
5.58
9.74
---------
9.69
7.23
---------
7.15
66.42
------------
66.50
5.60
---------
5.58
9.78
---------
9.69
7.07
---------
7.15
127–129
229–231
186–187
98–100
203–205
117–119
65.74
------------
65.59
5.80
---------
5.83
13.50
------------
13.50
9.67
---------
9.95
62.14
------------
62.38
5.49
---------
5.54
12.75
------------
12.84
9.43
---------
9.46
63.40
------------
63.34
5.94
---------
5.91
12.35
------------
12.31
9.01
---------
9.07
55.83
------------
55.91
6.44
---------
6.50
15.11
------------
15.05
10.97
------------
11.09
54.55
------------
54.36
6.41
---------
6.52
13.66
------------
13.59
10.10
------------
10.01
IIIj
71 (0)
* The yields of 5,7-dimethyl-2-(phosphorylamido)-1,8-naphthyridines by method A are parenthesized.
laboratory for microanalysis at the Institute of Organo- O-ethyl chloromethylphosphonate IIi [15] were syn-
thesized by known procedures.
element Compounds, RAS.
Synthesis of 5,7-dimethyl-2-(phosphorylamido)-
1,8-naphthyridines IIIa–IIIg (method A). To a sus-
pension of 867 mg (5 mmol) of aminonaphthyridine I
and 606 mg (6 mmol) of abs. triethylamine in 10 mL
of abs. pyridine, 5 mmol of corresponding chloride II
was added dropwise at room temperature. The reaction
mixture was heated under reflux for 5 h, pyridine was
removed in the vacuum of a water-jet pump, and the
residue was dissolved in 20 mL of CHCl3, washed with
water (2 × 15 mL), dried over MgSO4, and chromato-
graphed on 8 g of Al2O3 (elution with CHCl3). The sol-
vent was removed from the eluate, and the residue was
recrystallized from tert-butyl methyl ether.
All operations were carried out in an argon atmo-
sphere. Solvents purified and dried by known proce-
dures [9] and saturated with argon were used. Diphe-
nylphosphinic chloride IIa, diphenyl chlorophosphate
IIb, methylphenylphosphinic chloride IIf, and diethyl
chlorophosphate IIj (Aldrich) were purified by vacuum
distillation. 2-Amino-5,7-dimethyl-1,8-naphthyridine I
[10], bis(o-tolyl) chlorophosphate IIc [11], bis(m-tolyl)
chlorophosphate IId [12], bis(p-tolyl) chlorophosphate
IIe [11], O-phenyl chloromethylphosphonate IIg [13],
O-ethyl chlorophenylphosphonate IIh [14], and
Table 2. Distribution ratios
Synthesis of 5,7-dimethyl-2-(phosphorylamido)-
1,8-naphthyridines IIIa–IIIj (method B). To a sus-
pension of 867 mg (5 mmol) of aminonaphthyridine I
in 20 mL of abs. CHCl3, 5 mmol of corresponding chlo-
ride II was added dropwise. The mixture was stirred for
5 min at room temperature, and 606 mg (6 mmol) of
abs. triethylamine was added dropwise. The reaction
mixture was refluxed until complete dissolution of the
initial aminonaphthyridine, cooled, washed with water
Concentra-
tion, mol/L
U(VI)
Th(IV)
La(III)
Nd(III)
HNO3 0.77
HNO3 2.81
HNO3 5.40
Na2CO3 0.47
0.10
0.17
0.36
0.02
–
0.05
–
0.05
0.1
0.15
0.27
0.32
2.00
0.23
1.43
0.2
DOKLADY CHEMISTRY Vol. 425 Part 2 2009

SYNTHESIS AND EXTRACTION PROPERTIES OF FIRST REPRESENTATIVES
87
3. Musikas, C., Inorg. Chim. Acta, 1987, vol. 140, pp. 197–
(2 × 20 mL), dried over MgSO4, and treated further as
206.
in method A.
4. Kolarik, Z. and Mullich, U., Solvent Extr. Ion Exch.,
Extraction of U(VI), Th(IV), La(III), and
Nd(III). In test tubes with ground-glass stoppers, the
following components were placed: 1.5 mL of a solu-
tion of HNO3 of different concentrations or Na2CO3,
0.5 mL of a metal solution in 0.01 M HNO3, and 2 mL
of a 0.01 M solution of 5,7-dimethyl-2-(diphenylphos-
phinamido)-1,8-naphthyridine IIIa in chloroform (the
ligand solution was prepared by dissolving a weighed
sample). The phases were allowed to contact for
15 min. Phase separation was performed by centrifug-
ing. The phases were isolated, and an aliquot of the
aqueous phase was sampled for spectrophotometric
analysis for U(VI), Th(IV), La(III), and Nd(III) with
Arsenazo III followed by calculation of metal distribu-
tion ratios. The distribution ratios were determined as
the ratio of the metal content in the organic phase to its
content in the aqueous phase. Extraction was studied
under static conditions at 20 1°C.
1997, vol. 15, no. 3, pp. 361–379.
5. Kolarik, Z., Mullich, U., and Gassner, F., Solvent Extr.
Ion Exch., 1999, vol. 17, no. 1, pp. 23–32.
6. He, C. and Lippard, S.J., Tetrahedron, 2000, vol. 56,
no. 42, pp. 8245–8252.
7. Paudler, W.W. and Sheets, R.M., Adv. Heterocycl.
Chem., 1983, vol. 33, pp. 147–184.
8. Matveeva, A.G., Lemrort, R.S., Peregudov, A.S.,
Matveev, S.V., and Nifant’ev, E.E., Abstracts of Papers,
XV Mezhdunar. konf. po khimii soedinenii fosfora, pos-
vyashchennaya 100-letiyu so dnya rozhdeniya M.I. Ka-
bachnika (XV International Conference on the Chemis-
try of Phosphorus Compounds dedicated to the 100th
Anniversary of the Birth of M.I. Kabachnik), St. Peters-
burg, 2008, p. 54.
9. Weissberger, A., Proskauer, E.S., Riddik, J.A., and
Toops, E.E., Organic Solvents. Physical Properties and
Methods of Purifications, NewYork: Interscience, 1955.
Translated under the title Organicheskie rastvoriteli,
Moscow: Inostrannaya Literatura, 1958.
ACKNOWLEDGMENTS
10. Bernstein, J., Stearns, B., Shaw, E., and Lott, W.A.,
J. Am. Chem. Soc., 1947, vol. 69, no. 5, pp. 1151–1158.
This work was supported by the Presidium of the
RAS (program n. 8 “Development of Methods of Syn-
thesis of Chemical Substances and Design of New
Materials”).
11. Khodak, A.A., Tikhonina, N.A., Porshnev, Yu.N., and
Gilyarov, V.A., Izv. Akad. Nauk SSSR. Ser Khim., 1987,
no. 11, pp. 2547–2550.
12. Goryunov, E.I., Zakharov, L.S., Petrovskii, P.V., and
Kabachnik, M.I., Izv. Akad. Nauk SSSR, Ser. Khim.,
1985, no. 4, pp. 878–882.
REFERENCES
13. Tomchina, L.F., Zavlin, P.M., and Razumovskii, V.V.,
1. Glagolenko, Yu.V., Dzekun, E.G., Rovnyi, S.I., Sazh-
nov, V.K., Ufimtsev, V.P., Broshevitskii, V.S., Lap-
tev, G.A., Osnovin, V.I., Zakarkin, B.S., Smelov, V.S.,
Nenarokomov, E.A., and Nikipelov, B.V., Vopr. Radiats.
Bezopasnosti, 1997, no. 2, pp. 3–18.
Zh. Obshch. Khim., 1968, vol. 38, no. 3, pp. 564–566.
14. Gaumont, A.C., Morise, X., and Denis, J.M., J. Org.
Chem., 1992, vol. 57, no. 15, pp. 4292–4295.
15. Pudovik, A.N., Kashevarova, E.I., and Gorcha-
kova, V.M., Zh. Obshch. Khim., 1964, vol. 34, no. 7,
pp. 2213–2218.
2. Rozen, A.M. and Krupnov, B.V., Usp. Khim., 1996,
vol. 65, no. 11, pp. 1052–1079.
DOKLADY CHEMISTRY Vol. 425 Part 2 2009