Synthesis of nitro and amino derivatives of benzothiacrown ethers

Article abstract of DOI:10.1007/s11172-007-0150-9

The condensation reaction of 1,2-bis(2-haloethoxy)-4-nitrobenzenes with acyclic α,ω-(oxa)alkanedithiols in the presence of alkali metal carbonates produced a series of nitrobenzodithiacrown ethers with macrocycles of different size. The structures of thre

Full text of DOI:10.1007/s11172-007-0150-9

Russian Chemical Bulletin, International Edition, Vol. 56, No. 5, pp. 993—1002, May, 2007
993
Synthesis of nitro and amino derivatives of benzothiacrown ethers
S. N. Dmitrieva,a N. I. Sidorenko,b A. I. Vedernikov,a L. G. Kuz´mina,c
J. A. K. Howard,d T. M. Buslaeva,b and S. P. Gromova
ꢀ
aPhotochemistry Center, Russian Academy of Sciences,
7a ul. Novatorov, 119421 Moscow, Russian Federation.
Fax: +7 (495) 936 1255. Eꢀmail: gromov@photonics.ru
bM. V. Lomonosov Moscow State Academy of Fine Chemical Technology,
86 prosp. Vernadskogo, 119571 Moscow, Russian Federation.
Fax: +7 (495) 434 8711
cN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
31 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (495) 954 1279
dDepartment of Chemistry, University of Durham,
South Road, Durham DH1 3LE, UK
The condensation reaction of 1,2ꢀbis(2ꢀhaloethoxy)ꢀ4ꢀnitrobenzenes with acyclic
α,ωꢀ(oxa)alkanedithiols in the presence of alkali metal carbonates produced a series of
nitrobenzodithiacrown ethers with macrocycles of different size. The structures of three ethers
were established by Xꢀray diffraction. A new method was developed for the synthesis of
nitrobenzomonothiaꢀ15ꢀcrownꢀ5 ether. Nitro derivatives of benzodithiacrown ethers were
tested as reagents for extraction of palladium(II), platinum(IV), and rhodium(III) from hydroꢀ
chloric acid solutions. Extraction of PdII salts was found to be highly selective compared to that
of PtIV and RhIII salts. Benzodithiaꢀ15ꢀcrownꢀ5 ether is the most efficient extractant for
palladium(II). Reduction of nitrobenzothiacrown ethers with hydrazine hydrate in the presꢀ
ence of a platinum catalyst afforded their amino derivatives.
Key words: 1,2ꢀbis(2ꢀhaloethoxy)ꢀ4ꢀnitrobenzenes, α,ωꢀ(oxa)alkanedithiols, condensation,
nitrobenzothiacrown ethers, Xꢀray diffraction study, reduction, aminobenzothiacrown ethers,
extraction, palladium.
Scheme 1
Thiacrown ethers are among the most promisꢀ
ing macrocyclic sulfides.1,2 Sulfurꢀcontaining macroꢀ
heterocycles have attracted interest because these comꢀ
pounds can form stable complexes with transition and
heavy metal ions.3,4 These compounds can be used
as selective extractants, materials for ionꢀselective
electrodes, reagents for modifications of chromatoꢀ
graphic sorbents, etc. The development of procedures for
the synthesis of important functionalized derivatives of
thiacrown ethers is of great importance for the extenꢀ
sion of the possibilities of the practical use of these comꢀ
pounds.
In the present study, we developed convenient proceꢀ
dures for the synthesis of nitro and amino derivatives of
benzothiacrown ethers with macrocycles of different size
and different combinations of O and S atoms. The conꢀ
densation reactions of 1,2ꢀbis(2ꢀhaloethoxy)ꢀ4ꢀnitrobenꢀ
zenes 1a,b with terminal (oxa)alkanedithiols 2a—d in the
presence of alkali metal carbonates (M2CO3) in aqueous
ethanol produced nitrobenzodithiacrown ethers 3a—d in
48—89% yields (Scheme 1). To suppress side reactions,
1: X = Cl (a), I (b)
2, 3
a
n
0
1
M
Cs
Li
2, 3
c
d
n
2
3
M
Na
K
b
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 958—966, May, 2007.
1066ꢀ5285/07/5605ꢀ0993 © 2007 Springer Science+Business Media, Inc.

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Dmitrieva et al.
condensation was performed under highꢀdilution conꢀ
ditions.
ethoxy)benzaldehydes,5 we used diiodide 1b in the synꢀ
thesis of compound 3a, whereas other nitrobenzodithiaꢀ
crown ethers 3b—d were prepared starting from dichloꢀ
ride 1a. Compounds 3a,c,d were synthesized for the first
time. Compound 3b has been prepared earlier6 by conꢀ
densation of diiodide 1b with dithiol 2b in the presence of
Na2CO3 in 58% yield. The conditions proposed in the
present study allowed the synthesis of crown ether 3b
from dichloride 1a in substantially higher yield (89%),
one reaction step being eliminated.
High yields achieved in the presence of Li2CO3 (in the
synthesis of 15ꢀmembered macrocycle 3b), Na2CO3 (in
the synthesis of 18ꢀmembered macrocycle 3c), or K2CO3
(in the synthesis of 21ꢀmembered macrocycle 3d) are most
likely attributed to the best correspondence between the
size of the metal cation, which is partially (in the case of
Na+ or K+) or completely (in the case of Li+) hydrated in
an aqueous alcoholic solution, and the size of the cavity
of the intermediate in the cyclization step giving dithiaꢀ
crown ether. The good yield of 12ꢀmembered macrocycle
3a achieved in the reaction with the use of Cs2CO3 is
apparently due to the specific template effect of the
Cs+ ion. This effect has been observed in the synthesis of
sulfurꢀcontaining crown compounds with macrocycles of
different size.7,8
We chose alkali metal carbonates for the synthesis of
compounds 3a—d based on the data, which we have obꢀ
tained earlier5 in studying the influence of the metal catꢀ
ion on the efficiency of condensation of 3,4ꢀbis(2ꢀ
haloethoxy)benzaldehydes with dithiols 2a—d in the synꢀ
thesis of formyl derivatives of benzodithiacrown comꢀ
pounds.
Apparently, the reactions of dihalides 1a,b with dithiols
2a—d start with deprotonation of dithiol under the action
of bases in an aqueous ethanolic solution giving rise to the
thiolate anion or its ion pair (Scheme 2). The nucleoꢀ
philic substitution at one of the terminal saturated carbon
atoms of dihalide affords podand 4. Subsequent deꢀ
protonation of the thiol group and cyclization of the reꢀ
sulting ion pair consisting of the hydrated metal ion
and the anion of podand 4 give compounds 3a—d.
The hydrated cation can form additional coordination
bonds involving the oxygen atoms of dihalide and dithiol
through partial dehydration. Apparently, this preorgaꢀ
nization of the intermediate provides the basis for the
template effect of the metal ion facilitating the loss of the
halide ion as a result of the intramolecular nucleophilic
substitution.
Since we succeeded in synthesizing the formyl deꢀ
rivative of benzodithiaꢀ12ꢀcrownꢀ4 ether only starting
from diiodide 1b, and the yields of formylbenzodithiaꢀ
15(18,21)ꢀcrownꢀ5(6,7) ethers were virtually indepenꢀ
dent of the nature of the halide ion in 3,4ꢀbis(2ꢀhaloꢀ
A procedure for the synthesis of the nitro derivative of
benzomonothiaꢀ15ꢀcrownꢀ5 ether 3e by condensation
of 1,2ꢀbis[2ꢀ(tosyloxy)ethoxy]ꢀ4ꢀnitrobenzene with
bis(2ꢀhydroxyethyl)sulfide in the presence of ButONa in
tertꢀbutyl alcohol was documented.9 We developed a new
Scheme 2
n = 0—3
+ is an alkali metal cation with different degrees of hydration
Q

Nitroꢀ and aminobenzothiacrown ethers
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 5, May, 2007
995
Scheme 3
approach to the synthesis of compound 3e from available
4ꢀnitropyrocatechol (5) and 2ꢀ(2ꢀchloroethoxy)ethanol
(6) (Scheme 3). The reaction of compounds 5 and 6 in
the presence of a base produced dithiol 7. A small amount
of nitrophenol 8, which was produced via alkylation of
4ꢀnitropyrocatechol (5) at the hydroxy group located in
the para position with respect to the nitro group, was
isolated along with the dithiol. Two different nitrophenols
can theoretically be formed as a result of alkylation at one
of two hydroxy groups of pyrocatechol 5. The fact that the
reaction produced nitrophenol 8 was confirmed by NOE
experiments. Thus, the 2D spectrum shows an intense
crossꢀpeak between the methylene protons of the CH2OAr
group and the proton of the benzene ring in the
meta position with respect to the nitro group. Based on
these data, the mechanism of formation of diol 7 can be
suggested. Apparently, deprotonation of 4ꢀnitropyroꢀ
catechol (5) with a base initially occurs at the more acidic
hydroxy group in the para position with respect to the
electronꢀwithdrawing nitro group to give the phenolate
ion. The nucleophilic substitution of the chlorine atom in
2ꢀ(2ꢀchloroethoxy)ethanol (6) with this ion affords nitroꢀ
phenol 8. The next step involves deprotonation of the
second hydroxy group in the benzene ring of compounds 8
under the action of the base followed by alkylation of the
resulting phenolate with an excess of compound 6 to give
diol 7. The treatment of diol 7 with thionyl chloride in
the presence of pyridine affords dichloride 9, and the
reaction of the latter with sodium sulfide produces
benzomonothiacrown ether 3e in substantially higher yield
(64% in the absence of a base and 73% in the presence of
Na2CO3) compared to that obtained according to the
procedure described earlier9 (18%).
Reduction of nitrobenzothiacrown ethers 3a—e
with hydrazine hydrate in the presence of platinum on
carbon afforded amino derivatives 10a—e in high yields
(Scheme 4).
Scheme 4
3, 10
X
Y
n
3, 10
X
Y
n
a
b
c
S
S
S
O
O
O
0
1
2
d
e
S
O
O
S
3
1
It should be noted that this reaction imposes stringent
requirements on the purity of the starting nitro comꢀ
pounds. In the case of chromatographically pure nitroꢀ
benzothiacrown ethers, which were not recrystallized,
a larger amount of the catalyst was required for complete
reduction due, probably, to partial poisoning of its active

996
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 5, May, 2007
Dmitrieva et al.
surface by traces of dithiols used in the synthesis of nitro
compounds or traces of byꢀproducts containing the
mercapto group.
its active surface with traces of dithiol 2c used in the
synthesis of nitro derivative 3c.
The structures of the resulting compounds were estabꢀ
lished by 1H and 13C NMR and IR spectroscopy and were
confirmed by mass spectrometry and elemental analysis
(Tables 1—3).
The threeꢀdimensional structures of nitrobenzodiꢀ
thiacrown ethers 3a,c,d were studied by Xꢀray diffraction.
Their crystal structures are shown in Figs 1—3. Selected
bond lengths and bond angles are given in Table 4. In the
structure of 3a, the crown macrocycle is disordered over
two orientations of the C(10)—C(11) chain between the
S(1) and S(2) atoms (the atomic numbering scheme used
in Figs 1—3 differs from the IUPAC nomenclature). This
disorder, as well as high mosaicity of the crystals, resulted
in a decrease in the accuracy of the Xꢀray diffraction data
for 3a,c. In spite of this, a comparison of molecules 3a,c,d
Compounds 3a—e were reduced by analogy with the
known procedure9 for the synthesis of aminobenzoꢀ
monothiaꢀ15ꢀcrownꢀ5 ether (10e) using the platinum
catalyst instead of the palladium catalyst. The platinum
catalyst proved to be much more efficient in the synthesis
of amino derivatives 10a—e. For example, an attempt to
reduce compound 3c in the presence of the Pd/C catalyst
(10%) led to an increase in the reaction time to 70 h,
whereas the reaction was completed in 7 h in the presence
of a smaller amount of the Pt/C catalyst (10%). The difꢀ
ference in the reduction rate can also be associated with
higher resistance of the platinum catalyst to poisoning of
Table 1. Physicochemical characteristics, yields, and elemental
analysis data for compounds 3a—e, 7—9, and 10a—e
Comꢀ Rfa M.p./°C Yield Found
Molecular
formula
(%)
N
C(9)
poꢀ
(solvent) (%) Calculated
S(1)
und
C(8)
С
H
C(6)
3a
3b
3c
3d
3e
0.73 159—161 48 47.95 5.31 4.58 С12H15NO4S2
C(5)
C(7)
C(10A)
C(11B)
(AcOEt)
47.82 5.02 4.65
C(10B)
C(11A)
0.51 129—131b 89
—
—
—
С14H19NO5S2
O(2)
(EtOH)
O(3)
C(4)
N(1)
0.39 128—129 67 48.75 6.12 3.54 С16H23NO6S2•
O(1)
(hexane)
48.78 6.01 3.56 •0.25H2O
C(2)
0.61
69–71
(hexane)
58 49.77 6.52 3.17 С18H27NO7S2
49.87 6.28 3.23
C(3)
0.49 105—107c 73
—
—
—
С14H19NO6S
S(2)
O(4)
(pentane)
C(1)
C(12)
7 d
8 d
0.34
Oil
28
3
—
—
—
—
—
—
C14H21NO8
С10H13NO6
0.49 115—117
(hexane)
Fig. 1. Crystal structure of nitrobenzodithiacrown ether 3a. Here
and in Figs 2 and 3, the displacement ellipsoids are drawn at the
50% probability level.
9 d
0.63
Oil
93
—
—
—
C14H19Cl2NO6
10a 0.42 119–121 88 53.22 6.17 4.99 С12H17NO2S2
(EtOH) 53.11 6.31 5.16
87—89 95 52.52 6.54 4.17 С14H21NO3S2•
(EtOH) 52.55 6.77 4.38 •0.25H2O
80—82 83 52.58 7.25 3.65 C16H25NO4S2•
10b 0.37
10c 0.35
10d e 0.30
S(1)
C(9)
C(8)
C(10)
(EtOH)
52.79 7.06 3.85 •0.25H2O
C(11)
Oil
90
—
—
—
—
—
—
C18H29NO5S2
С14H21NO4S
10e 0.26 131—133f 95
C(7)
O(2)
O(1)
(EtOH)
O(3)
C(12)
C(13)
C(6)
C(5)
a In benzene—AcOEt, 10 : 1 (3a—c), benzene—AcOEt, 1 : 1 (3d),
benzene—AcOEt, 5 : 1 (3e), benzene—EtOH, 5 : 1 (7—9), and
benzene—EtOH, 10 : 1 (10a—e), systems.
O(4)
C(4)
b Cf. lit. data6: m.p. 125—126 °C.
C(2)
C(1)
O(5)
C(16)
S(2)
C(14)
c Cf. lit. data9: m.p. 104—105 °C.
C(3)
d The highꢀresolution mass spectrum is given in the Experimenꢀ
tal section.
N(1)
C(15)
e The highꢀresolution mass spectrum, found: m/z 403.1488 [M]+.
O(6)
C
18H29NO5S2. Calculated: M = 403.1487.
f Cf. lit. data9: m.p. 132—134 °C.
Fig. 2. Crystal structure of nitrobenzodithiacrown ether 3c.

Nitroꢀ and aminobenzothiacrown ethers
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 5, May, 2007
997
Table 2. IR, 1H NMR, and mass spectra of compounds 3a,c,d, 7—9, and 10a—d
Comꢀ
IR
1H NMR (CDCl3),
MS,
m/z (Irel (%))*
pound (KBr), ν/cm–1
δ (J/Hz)
3а
3c
1515 (NO2)
1513 (NO2)
2.99 (m, 4 H, 2 СH2S); 3.06 (s, 4 H, 2 СH2S); 4.43 (m, 4 H,
2 СH2ОAr); 6.85 (d, 1 H, H(14), J = 9.0); 7.69 (d, 1 H,
H(11), J = 2.3); 7.93 (dd, 1 H, H(13), J = 9.0, J = 2.3)
301 [M]+ (61), 241 (60), 181 (100),
166 (60), 92 (85), 87 (79), 79 (65),
64 (72), 61 (75), 51 (61)
389 [M]+ (11), 181 (67), 148 (83),
105 (81), 89 (77), 87 (100), 79 (55),
61 (95), 60 (100), 59 (92), 58 (99)
2.96 (t, 2 H, СH2S, J = 6.6); 2.99 (t, 2 H, СH2S, J = 6.9);
3.15 (t, 2 H, СH2S, J = 6.4); 3.18 (t, 2 H, СH2S, J = 6.6);
3.62 (s, 4 H, 2 СH2О); 3.74 (t, 2 H, СH2О, J = 6.6); 3.75
(t, 2 H, СH2О, J = 6.9); 4.27 (m, 4 H, 2 СH2ОAr); 6.87
(d, 1 H, H(20), J = 9.0); 7.71 (d, 1 H, H(17), J = 2.5);
7.91 (dd, 1 H, H(19), J = 9.0, J = 2.5)
3d
1513 (NO2)
2.949 (t, 2 H, СH2S, J = 6.4); 2.954 (t, 2 H, СH2S, J = 6.3);
3.06, 3.07 (both t, 2 H each, 2 СH2S, J = 6.2); 3.67 (s, 8 H,
4 СH2О); 3.78 (t, 2 H, СH2О, J = 6.4); 3.79 (t, 2 H, СH2О,
J = 6.3); 4.27, 4.29 (both t, 2 H each, 2 СH2ОAr, J = 6.2);
6.90 (d, 1 H, H(23), J = 9.2); 7.74 (d, 1 H, H(20), J = 2.6);
7.91 (dd, 1 H, H(22), J = 9.2, J = 2.6)
433 [M]+ (10), 193 (61), 151 (64),
105 (86), 89 (91), 87 (100), 86 (64),
73 (58), 71 (72), 61 (95), 60 (88)
7
3370 (OH);
1515 (NO2)
2.66 (br.s, 2 H, 2 OH); 3.70, 3.77, 3.96 (all m, 4 H each,
6 СH2О); 4.26 (m, 4 H, 2 СH2ОAr); 6.93 (d, 1 H, H(6),
J = 9.0); 7.78 (d, 1 H, H(3), J = 2.8); 7.91 (dd, 1 H,
H(5), J = 9.0, J = 2.8)
331 [M]+ (75), 182 (60), 181 (73),
166 (47), 165 (40), 155 (45), 89 (100),
87 (49), 79 (42), 73 (37)
8
9
3404, 3111
(OH); 1512
(NO2)
3.72, 3.84, 3.93 (all m, 2 H each, 3 СH2О); 4.27 (m, 2 H,
СH2ОAr); 6.89 (d, 1 H, H(3), J = 9.5); 7.77 (dd, 1 H,
H(4), J = 9.5, J = 2.6); 7.78 (d, 1 H, H(6), J = 2.6)
243 [M]+ (22), 181 (42), 89 (100),
79 (32), 69 (33), 57 (32), 55 (24),
53 (52), 52 (49), 51 (38)
371 (2 37Cl) [M]+ (2), 369 (35Cl, 37Cl)
[M]+ (33), 367 (2 35Cl) [M]+ (46),
182 (24), 181 (45), 109 (49), 107 (94),
89 (82), 79 (21), 65 (58), 63 (100)
1515 (NO2)
3.669, 3.672 (both t, 2 H each, 2 СH2О, J = 5.9); 3.87 (t, 4 H,
2 СH2Cl, J = 5.9); 3.95 (m, 4 H, 2 СH2О); 4.27 (m, 4 H,
2 СH2ОAr); 6.96 (d, 1 H, H(6), J = 9.1); 7.81 (d, 1 H, H(3),
J = 2.7); 7.91 (dd, 1 H, H(5), J = 9.1, J = 2.7)
10a
10b
3448, 3362
(NH2)
2.89, 2.94 (both m, 2 H each, 2 СH2S); 3.07 (m, 4 H, 2 СH2S); 271 [M]+ (89), 183 (78), 151 (84),
3.49 (br.s, 2 H, NH2); 4.30 (m, 4 H, 2 СH2OAr); 6.24 (dd,
1 H, H(13), J = 8.2, J = 2.7); 6.25 (br.s, 1 H, H(11));
6.67 (d, 1 H, H(14), J = 8.2)
99 (53), 95 (100), 92 (53), 87 (39),
67 (27), 60 (38), 58 (85)
3419, 3345
(NH2)
2.89 (t, 2 H, СH2S, J = 6.1); 2.96 (t, 2 H, СH2S, J = 6.6);
3.04 (t, 2 H, СH2S, J = 6.1); 3.06 (t, 2 H, СH2S, J = 5.5);
3.79 (t, 2 H, СH2О, J = 6.1); 3.80 (t, 2 H, СH2О, J = 6.6);
4.15 (t, 2 H, СH2ОAr, J = 6.1); 4.20 (t, 4 H, СH2ОAr,
J = 5.5); 6.24 (dd, 1 H, H(16), J = 8.5, J = 2.6); 6.30
(d, 1 H, H(14), J = 2.6); 6.74 (d, 1 H, H(17), J = 8.5)
315 [M]+ (34), 272 (57), 151 (100),
149 (21), 107 (18), 93 (20), 92 (93),
79 (18), 70 (24), 61 (31)
10c
10d
3425, 3387
(NH2)
2.92, 2.93 (both t, 2 H each, 2 СH2S, J = 6.4); 3.04, 3.11
(both t, 2 H each, 2 СH2S, J = 6.6); 3.48 (br.s, 2 H, NH2);
3.63 (s, 4 H, 2 СH2О); 3.73, 3.75 (both t, 2 H each, 2 СH2О,
J = 6.4); 4.11, 4.14 (both t, 2 H each, 2 СH2ОAr, J = 6.6);
6.22 (dd, 1 H, H(19), J = 8.5, J = 2.4); 6.29 (d, 1 H, H(17),
J = 2.4); 6.70 (d, 1 H, H(20), J = 8.5)
359 [M]+ (8), 152 (26), 151 (100),
103 (23), 95 (46), 89 (34), 87 (50),
67 (29), 61 (62), 60 (66), 59 (52)
3422, 3352
(NH2)
2.88 (t, 2 H, СH2S, J = 6.6); 2.91 (t, 2 H, СH2S, J = 6.4);
2.97 (t, 2 H, СH2S, J = 6.6); 3.01 (t, 2 H, СH2S, J = 6.5);
3.657, 3.664 (both s, 4 H each, 4 СH2О); 3.75 (t, 2 H, СH2О,
J = 6.6); 3.77 (t, 2 H, СH2О, J = 6.4); 4.11 (t, 2 H, СH2ОAr,
J = 6.6); 4.15 (t, 2 H, СH2ОAr, J = 6.5); 6.23 (dd, 1 H,
H(22), J = 8.2, J = 2.6); 6.30 (d, 1 H, H(20), J = 2.6); 6.74
(d, 1 H, H(23), J = 8.2)
403 [M]+ (24), 191 (22), 151 (100),
95 (36), 89 (47), 87 (51), 86 (25),
71 (32), 61 (48), 60 (43)
* The molecular ion peak and ten most intense peaks are given. The ionization energies were 60 (7 and 10d) and 70 eV (other
compounds).

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Dmitrieva et al.
Table 3. 13C NMR spectra of compounds 3c, 7—9, and 10d
Table 4. Selected bond lengths (d) and bond angles (ω) in
the structures of 3a,c,d
Comꢀ
pound
13C NMR,
δ
Parameter
Bond
3a
3c
3d
3c
7
29.79 (2 SCH2CH2OAr); 30.70 (2 CH2S); 69.47
(2 CH2O); 69.90, 69.98 (both CH2OAr); 71.46, 71.60
(both CH2O); 106.80 (C(17)); 111.31 (C(20)); 117.66
(C(19)); 140.58 (C(18)); 147.41 (C(16a)); 153.49
(C(20a))
d/Å
O(1)—C(1)
O(1)—C(2)
O(2)—C(7)
O(2)—C(8)
O(1)...O(2)
1.398(12) 1.455(8) 1.447(2)
1.394(11) 1.373(8) 1.371(2)
1.323(11) 1.347(11) 1.360(2)
1.460(11) 1.446(10) 1.450(2)
61.41 (2 CH2ОH); 68.66 (3 CH2О); 68.74, 72.74,
72.77 (all CH2О); 107.77, 111.03 (C(3), C(6));
117.95 (C(5)); 141.41 (C(4)); 147.91 (C(2));
153.70 (C(1))
2.49
2.58
2.61
Angle
ω/deg
C(1)—O(1)—C(2)
C(7)—O(2)—C(8)
C(11)—O(3)—C(12)
C(13)—O(4)—C(14)
C(15)—O(5)—C(16)
O(1)—C(2)—C(3)
O(1)—C(2)—C(7)
O(2)—C(7)—C(2)
O(2)—C(7)—C(6)
119.6(8) 116.8(6) 117.3(2)
120.8(7) 118.0(7) 116.9(2)
—
—
—
125.3(9) 126.6(8) 124.3(2)
114.5(8) 113.3(7) 115.9(2)
113.3(8) 116.5(6) 115.6(2)
125.9(9) 123.3(8) 124.2(2)
8
9
61.58 (CH2O); 68.96, 69.03 (CH2OAr, CH2CH2OAr);
72.63 (CH2O); 111.07 (C(6)); 111.95 (C(3)); 116.39
(C(4)); 142.63 (C(5)); 146.82 (C(1)); 151.34 (C(2))
114.6(7) 113.2(2)
110.3(7) 112.5(2)
—
112.4(2)
42.70, 42.76 (both CH2Cl); 68.95, 69.07, 69.36, 69.46
(2 CH2ОAr, 2 CH2CH2ОAr); 71.60, 71.64
(both CH2О); 108.77, 111.79 (C(3), C(6)); 118.07
(C(5)); 141.50 (C(4)); 148.30 (C(2)); 154.22 (C(1))
10d
31.20, 31.35 (both SCH2CH2OAr); 31.91, 32.12
(both CH2S); 69.39 (CH2OAr); 70.29, 70.31 (both
CH2О); 70.76 (CH2OAr); 70.98, 71.04 (both CH2О);
71.42 (2 CH2О); 102.22 (C(20)); 107.05 (C(22));
116.58 (C(23)); 141.11 (C(23a)); 141.38 (C(19a));
149.63 (C(21))
bond angles in molecules 3a,c,d are increased, on the
average, to 124.9(6)°, whereas the O(1)—C(2)—C(7) and
O(2)—C(7)—C(2) bond angles are decreased, on the avꢀ
erage, to 114.9(6)°. Such distortions lead to a decrease
in the distance between the O(1) and O(2) atoms to
2.49—2.61 Å, which is smaller than the sum of the
van der Waals radii (~2.8 Å). This is mainly associated
with the conjugation of the lone electron pairs of the O(1)
and O(2) atoms located on the p orbitals with the benzene
ring.10,11 This conjugation is evidenced by the predomiꢀ
nantly sp2ꢀhybridized state of the O(1) and O(2) atoms,
resulting in the substantially shorter O(1)/O(2)—CAr disꢀ
tances compared to the O(1)/O(2)—CAlk distances (aver.,
1.361(8) and 1.443(8) Å, respectively) and the larger bond
angles at the O(1) and O(2) atoms compared to the bond
angles at the other O atoms (aver., 118.2(5) and 112.6(4)°,
respectively). This conjugation is favored by the conꢀ
formations of the C(1)—O(1)—C(2)—C(3) and
C(8)—O(2)—C(7)—C(6) fragments characterized by the
rather small torsion angles (0.8—14.2°). It should be noted
that the shortest O(1)...O(2) distance and the largest deꢀ
viations of the CAlk—O—CAr—CAr torsion angles from
the values ideal for conjugation (0 or 180°) were found in
compound 3a. This undoubtedly reflects the conformaꢀ
tional strain of the 12ꢀmembered macroheterocycle.
In all compounds, both sulfur atoms are located outꢀ
side the macrocyclic cavity, which is characteristic of the
singleꢀcrystal structures of benzothiacrown ethers.11,12 In
macrocycles with this geometry, the orbitals of the lone
electron pairs on the sulfur atoms should point away from
the center of the macrocycle. Taking also into account
that the distance between the S(1) and S(2) atoms in
compounds 3c and 3d is rather large (7.64 and 8.01 Å,
Note. The spectra of compounds 7—9 and 10d were recorded in
CDCl3; of compound 3c, in DMSOꢀd6.
based on the main geometric parameters revealed their
common features.
All compounds are characterized by a distortion of the
bond angles at the C(2) and C(7) atoms, which are shared
by two cyclic systems, exocyclic with respect to the benꢀ
zene ring. This distortion is typical of benzocrown sysꢀ
tems.10,11 The O(1)—C(2)—C(3) and O(2)—C(7)—C(6)
S(1)
C(9)
C(10)
C(8)
O(2)
C(12)
C(13)
C(11)
O(3)
C(6)
C(7)
C(2)
O(4)
C(14)
C(15)
C(5)
O(1)
C(1)
C(18)
C(4)
O(6)
C(3)
O(5)
C(16)
S(2)
N(1)
O(7)
Fig. 3. Crystal structure of nitrobenzodithiacrown ether 3d.
C(17)

Nitroꢀ and aminobenzothiacrown ethers
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 5, May, 2007
999
respectively), it can be concluded that the conformations
of the dithiacrown macrocycles observed in the crystals
are unfavorable for the formation of inclusion complexes
with metal ions. The data on the efficient extraction of
PdII salts with compounds 3a,c,d presented below suggest
that their dithiacrown systems are rather flexible in soluꢀ
tion due to which these systems can relatively easily adopt
conformations favorable for the complex formation. This
assumption agrees well with the fact that the macrocycle
in the crystal structure of 3a exists in two different conforꢀ
mations.
The nitro derivatives of benzodithiacrown ethers 3a—d
were tested as reagents for extraction of palladium(II),
platinum(IV), and rhodium(III) salts from hydrochloric
acid solutions. Solutions of K2[PdCl4], K2[PtCl6], and
Na3[RhCl6] at the concentration CM = 2•10–3 mol L–1 in
HCl (CA = 0.7 mol L–1) were used as models. The extracꢀ
tion was carried out with the use of solutions of comꢀ
pounds 3a—d in dichloromethane at the concentration
CE = 2•10–3 mol L–1. We chose dichloromethane beꢀ
cause of high solubility of the compounds under study in
this organic solvent and the fast phase separation after
extraction. The use of carbon tetrachloride, benzene, or
toluene as the solvent resulted in the formation of phases
of difficultly separable emulsions in the course of mixing.
The data on the extraction of PdII, PtIV, and RhIII salts
under the aboveꢀdescribed conditions are presented in
Table 5. As can be seen from these data, benzodithiacrown
ethers are rather efficient extractants for palladium(II),
which could be expected because PdII, being a soft acid
(in accord with Pearson’s hardꢀsoft acidꢀbase principle),
forms stable complexes with Sꢀ and S,Nꢀcontaining molꢀ
ecules. Because of this, the compounds under study proved
to be inefficient for extraction of platinum(IV) and
rhodium(III) belonging to hard acids. In addition, it should
be taken into account that highly charged rhodium(III)
complexes are difficult to extract because of their high
hydrophilicity. Among the nitro derivatives of benzodiꢀ
thiacrown ethers under examination, compound 3b conꢀ
taining the 15ꢀmembered macrocycle is characterized by
the largest distribution coefficient in the extraction of
palladium(II). This is apparently due to the corresponꢀ
dence between the sizes of the complex ion and the macꢀ
rocyclic ligand. However, the unambiguous conclusion
can be drawn only after the synthesis of individual pallaꢀ
dium complexes with the compounds in question.
To summarize, we developed new convenient and efꢀ
ficient procedures for the synthesis of nitro and amino
derivatives of benzothiacrown ethers with macrocycles of
different size and different combinations of heteroatoms O
and S. In the crystalline state, the sulfur atoms of the
dithiacrown fragment were demonstrated to be oriented
unfavorable for the simultaneous coordination of the metal
ion. However, the flexible macroheterocyclic fragment
can undergo a structural rearrangement in solution, thus
providing good binding of PdII salts. This was demonꢀ
strated by experiments on extraction. High selectivity of
extraction of PdII salts compared to that of PtIV and
RhIII salts was found.
Experimental
The 1H and 13C NMR spectra were recorded on a Bruker
DRX500 spectrometer (500.13 and 125.76 MHz, respectively)
in CDCl3 or DMSOꢀd6 using the solvent as the internal stanꢀ
dard (δ 7.27 and 2.50; δ 77.00 and 39.43, respectively). The
H
C
chemical shifts and spinꢀspin coupling constants were measured
with an accuracy of 0.01 ppm and 0.1 Hz, respectively. Twoꢀ
dimensional homonuclear 1H—1H COSY and heteronuclear
1H—13C COSY (HSQC and HMBC) spectra were used for the
assignment of the proton and carbon signals. The mass spectra
were obtained on Varian MAT 311A and Finnigan MATꢀ212
instruments. The highꢀresolution mass spectra were measured
on a Finnigan MATꢀ212 instrument (perfluorokerosene as the
standard) using a direct inlet system (the ionization energy was
60 or 70 eV). The IR spectra were recorded on Shimadzu IRꢀ435
and Bruker IFSꢀ113v spectrophotometers in films or KBr pellets.
The course of the reactions was monitored by TLC on
DCꢀAlufolien Kieselgel 60 F254 plates (Merck). Column
chromatography was performed with the use of silica gel
(Kieselgel 60, 0.063—0.100 mm, Merck).
Elemental analyses were carried out in the Laboratory of
Microanalysis of the A. N. Nesmeyanov Institute of Organoꢀ
element Compounds of the Russian Academy of Sciences and in
the Center of Collaborative Research of the M. V. Lomonosov
Moscow State Academy of Fine Chemical Technology.
The melting points were measured on a MELꢀTemp II inꢀ
strument in capillaries.
Table 5. Distribution coefficients (DM) for extraction of
palladium(II), platinum(IV), and rhodium(III) salts
(CM = 2•10–3 mol L–1) from an HCl solution (CA
0.7 mol L–1) with solutions of extractants 3a—d (CE
2•10–3 mol L–1) in dichloromethane
=
=
Comꢀ
pound
DM*
PdII
PtIV
RhIII
3a
3b
3c
3d
0.46
22.4
0.79
4.89
0.045
0.037
0.050
0.043
0.030
0.025
0.033
0.028
Dithiols 2a—c were commercial products (Aldrich).
3,6,9ꢀTrioxaꢀ1,11ꢀundecanedithiol (2d), 1,2ꢀbis(2ꢀchloroꢀ
ethoxy)ꢀ4ꢀnitrobenzene (1a), and 1,2ꢀbis(2ꢀiodoethoxy)ꢀ4ꢀ
nitrobenzene (1b) were prepared according to procedures deꢀ
scribed earlier.6,13
*DM = (0.002 – Caqeq)/Caqeq, where Caqeq is the equilibꢀ
rium concentration of metals in the aqueous phase after
extraction.
12ꢀNitroꢀ2,3,5,6,8,9ꢀhexahydroꢀ1,10,4,7ꢀbenzodioxadithiaꢀ
cyclododecene (3a). A solution of diiodide 1b (3.33 g, 7.2 mmol)

1000
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 5, May, 2007
Dmitrieva et al.
and 1,2ꢀethanedithiol (2a) (0.66 mL, 7.9 mmol) in ethanol
(450 mL) was added dropwise with stirring and refluxing to
a 1 : 1 aqueousꢀethanolic solution (360 mL) of Cs2CO3 (11.74 g,
36 mmol) under argon. The reaction mixture was refluxed for
20 h and concentrated in vacuo. Water (200 mL) was added to
the residue, and the mixture was extracted with chloroform. The
extracts were concentrated in vacuo, and the residue was puriꢀ
fied by silica gel column chromatography using benzene as the
eluent. The yield was 1.04 g (48%).
Nitrobenzodithiacrown ethers 3b—d (general procedure).
A solution of dichloride 1a (2.02 g, 7.2 mmol) and dithiol 2b—d
(7.9 mmol) in ethanol (300 mL) was added dropwise with stirꢀ
ring and refluxing to a 1 : 1 aqueousꢀethanolic solution (360 mL)
of M2CO3 (M = Li, Na, or K) (36 mmol) under argon. The
reaction mixture was refluxed for 48 h (for compounds 3b,c) or
77 h (for compound 3d) and concentrated in vacuo. Water
(200 mL) was added to the residue, and the mixture was extracted
with chloroform. The extracts were concentrated in vacuo, and
the residue was purified by silica gel column chromatography
using benzene and benzene—AcOEt (5 : 1) for 3b, benꢀ
zene—AcOEt (10 : 1) for 3c, and benzene—AcOEt (5 : 1) and
then benzene—AcOEt (1 : 1) for 3d as the eluents. The yields,
physicochemical parameters, and spectroscopic characteristics
of compounds 3b—d are given in Tables 1—3.
1,2ꢀBis[2ꢀ(2ꢀhydroxyethoxy)ethoxy]ꢀ4ꢀnitrobenzene (7) and
2ꢀ[2ꢀ(2ꢀhydroxyethoxy)ethoxy]ꢀ5ꢀnitrophenol (8). A solution of
2ꢀ(2ꢀchloroethoxy)ethanol (6) (5.1 mL, 48.3 mmol) in nꢀbutanol
(15 mL) was added dropwise with stirring to a boiling solution
of 4ꢀnitropyrocatechol (5) (2.50 g, 16.1 mmol) and NaOH
(2.07 g, 51.8 mmol) in nꢀbutanol (50 mL) under argon. The
reaction mixture was refluxed for 60 h and then concentrated
in vacuo. Water was added to the residue, and the mixture
was extracted with chloroform. The extracts were concenꢀ
trated in vacuo, and the residue was purified by silica gel column
chromatography using AcOEt as the eluent. Compounds 7
and 8 were obtained in yields of 1.37 g (28%) and 0.10 g (3%),
respectively. The highꢀresolution mass spectrum of comꢀ
pound 7, found: m/z 331.1268 [M]+. C14H21NO8. Calculated:
Table 6. Crystallographic parameters and the Xꢀray diffraction data collection and refinement statistics
for compounds 3a,c,d
Parameter
3а
3c
3d
Molecular formula
M
C12H15NO4S2
301.37
C16H23NO6S2
389.47
C18H27NO7S2
433.53
Crystal system
Space group
a/Å
b/Å
c/Å
Monoclinic
P21/c
Orthorhombic
P212121
4.7106(3)
12.8364(9)
30.351(2)
90
1835.3(2)
4
1.410
Orthorhombic
Pbca
8.1101(2)
18.5248(5)
27.3007(8)
90
15.0682(12)
10.4511(8)
8.6043(6)
97.526(4)
1343.33(18)
4
β/deg
V/Å3
4101.60(19)
8
Z
dcalc/g cm–3
F(000)
1.490
632
1.404
1840
824
µ(MoꢀKα)/mm–1
Crystal dimensions/mm
Scan mode/θꢀscanning
range/deg
0.405
0.46×0.12×0.08
ω/2.38—29.00
0.322
0.40×0.08×0.06
ω/1.72—28.99
0.299
0.36×0.36×0.16
ω/1.49—29.00
Ranges
of reflection
indices
Number of measured
reflections
Number of independent
reflections (Rint
Number of reflections
with I > 2σ(I )
–16 ≤ h ≤ 20,
–13 ≤ k ≤ 14,
–11 ≤ l ≤ 11
7845
–6 ≤ h ≤ 5,
–17 ≤ k ≤ 15,
–35 ≤ l ≤ 41
12533
–10 ≤ h ≤ 9,
–25 ≤ k ≤ 24,
–37 ≤ l ≤ 32
21988
3414
(0.1221)
1805
4819
(0.1141)
3188
5281
(0.0593)
3876
)
Number of refinement
189
226
361
variables
R Factors based on
reflections with I > 2σ(I )
R Factors based on
all reflections
Goodnessꢀofꢀfit on F 2
Residual electron
density (min/max)/e Å–3
R1 = 0.1681,
wR2 = 0.3190
R1 = 0.2587,
wR2 = 0.3509
1.095
R1 = 0.1277,
wR2 = 0.2846
R1 = 0.1765,
wR2 = 0.3069
1.097
R1 = 0.0494,
wR2 = 0.0867
R1 = 0.0779,
wR2 = 0.0932
1.055
–0.645/0.836
–0.606/1.295
–0.278/0.379

Nitroꢀ and aminobenzothiacrown ethers
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 5, May, 2007
1001
M = 331.1267. The highꢀresolution mass spectrum of comꢀ
pound 8, found: m/z 243.0742 [M]+. C10H13NO6. Calculated:
M = 243.07428.
and their weak reflection ability (the I/σ ratio was 3.9 and 3.2,
respectively). High mosaicity of the crystals made it imposꢀ
sible to choose the parameters for the correct integration of
experimental reflections using the SAINT program. In these
experiments, a large number of residual electron density peaks
were found in the region of the crown fragment, which is apparꢀ
ently indicative of a certain disorder of the macrocycle maniꢀ
fested in the existence of a series of similar conformations. Howꢀ
ever, we failed to extract these minor disorder components.
High flexibility of the macrocycles resulting in their disorder in
the crystals is, apparently, responsible for strong mosaicity of
the crystals.
The atomic coordinates and other experimental data were
deposited with the Cambridge Structural Database*
(CSD refcodes 615202 (3a), 615203 (3c), and 615204 (3d)).
Extraction was carried out in calibration tubes with ground
stoppers at room temperature. The volumetric ratio of the aqueꢀ
ous phase to the organic phases was 1 : 1. The stirring time was
10 min. The aqueous phases were analyzed after extraction by
the spectrophotometric method described earlier.16
1,2ꢀBis[2ꢀ(2ꢀchloroethoxy)ethoxy]ꢀ4ꢀnitrobenzene (9). A soꢀ
lution of SOCl2 (10.8 mL, 148 mmol) in chloroform (10 mL)
was added dropwise to a solution of compound 7 (2.4 g,
7.25 mmol) and pyridine (1.2 mL, 14.9 mmol) in chloroform
(10 mL) precooled to 0 °C. The reaction mixture was refluxed
for 25 h and then cooled. A 5% HCl solution was added with
stirring. The organic layer was separated, and the aqueous layer
was extracted with chloroform. The organic phases were comꢀ
bined and concentrated in vacuo, and the residue was purified by
silica gel column chromatography using a 5 : 1 benzene—AcOEt
mixture as the eluent. The yield was 2.5 g (93%). The
highꢀresolution mass spectrum, found: m/z 367.0589 [M]+.
C
14H19Cl2NO6. Calculated: M = 367.0589 (35Cl).
15ꢀNitroꢀ2,3,5,6,8,9,11,12ꢀoctahydroꢀ1,4,10,13,7ꢀbenzoꢀ
tetraoxathiacyclopentadecene (3e). A solution of dichloride 9
(0.21 g, 0.57 mmol) in ethanol (20 mL) was added dropwise with
stirring and refluxing to a 1 : 1 aqueousꢀethanolic solution
(40 mL) of Na2S•9H2O (0.75 g, 3.1 mmol) and Na2CO3 (0.08 g,
0.74 mmol) under argon. The reaction mixture was refluxed for
15 h, cooled, and concentrated in vacuo. Water was added to the
residue, and the mixture was extracted with chloroform. The
extracts were concentrated, and the residue was purified by silica
gel column chromatography using a 5 : 1 benzene—AcOEt mixꢀ
ture as the eluent. The yield was 0.14 g (73%).
This study was financially supported by the Russian
Foundation for Basic Research (Project No. 06ꢀ03ꢀ
32456), the Presidium of the Russian Academy of Sciꢀ
ences (Program No. 8), and the Mining and Metallurgiꢀ
cal Company Norilsk Nickel.
Aminobenzothiacrown ethers 10a—e (general procedure).
A solution of N2H4•H2O (0.47 mL, 9.7 mmol) in ethanol
(10 mL) was added dropwise with stirring and refluxing to
a solution of nitro compound 3a—e (0.3 mmol) and the
Pt/C (10%) catalyst (13 mg) in ethanol (40 mL) under argon.
The reaction mixture was refluxed for 3—8 h until the starting
nitro compound was completely consumed (TLC monitoring),
and the catalyst was filtered off. The filtrate was concentrated
in vacuo to dryness, water was added to the residue, and the
mixture was extracted with chloroform. The extracts were conꢀ
centrated in vacuo. The purity of the reaction products was
confirmed by 1H NMR spectroscopy. The yields, physicochemiꢀ
cal parameters, and spectroscopic characteristics of compounds
10a—e are given in Tables 1—3.
Xꢀray diffraction study. Single crystals of compounds 3a,c,d
suitable for Xꢀray diffraction were grown by slow evaporation of
solutions in a hexane—CH2Cl2 mixture. Single crystals of
dithiacrown ethers coated with perfluorinated oil were mounted
on a Bruker SMARTꢀCCD diffractometer under a flow of cooled
nitrogen (T = 120 K). The experimental Xꢀray diffraction data
sets were collected from the single crystals using the ωꢀscanning
technique and MoꢀKα radiation (λ = 0.71073 Å). The Xꢀray
reflections were processed using the Bruker SAINT software.14
The structures of 3a,c,d were solved by direct methods and
refined by the fullꢀmatrix leastꢀsquares method based on F 2
with anisotropic displacement parameters for all nonhydrogen
atoms. The hydrogen atoms were placed geometrically and reꢀ
fined using a riding model (for 3a,c) or isotropically (for 3d). All
calculations were performed with the use of the SHELXTLꢀPlus
program package.15 Crystallographic parameters and the Xꢀray
diffraction data collection and refinement statistics are given in
Table 6.
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Received September 27, 2006;
in revised form February 14, 2007