Synthesis of new metallomesogens based on 3-ketoesters

Article abstract of DOI:10.1134/S1070363213080148

Ethyl 3-(4-hydroxyphenyl)-3-ketopropionate was synthesized by acylation of acetoacetic ester with 4-acetoxybenzoyl chloride, followed by cleavage of aroylacetoacetic ester and hydrolysis of the protecting acetate group. Further esterification of the pheno

Full text of DOI:10.1134/S1070363213080148

ISSN 1070-3632, Russian Journal of General Chemistry, 2013, Vol. 83, No. 8, pp. 1556–1562. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © V.N. Kovganko, N.N. Kovganko, 2013, published in Zhurnal Obshchei Khimii, 2013, Vol. 83, No. 8, pp. 1326–1333.
Synthesis of New Metallomesogens Based on 3-Ketoesters
V. N. Kovgankoa and N. N. Kovgankob
a Belarus State Technological University, ul. Sverdlova 13-a, Minsk, 220050 Belarus
e-mail: umkauhanka@tut.by
b Belarus State Medical University, Minsk, Belarus
Received July 12, 2012
Abstract—Ethyl 3-(4-hydroxyphenyl)-3-ketopropionate was synthesized by acylation of acetoacetic ester with
4-acetoxybenzoyl chloride, followed by cleavage of aroylacetoacetic ester and hydrolysis of the protecting
acetate group. Further esterification of the phenol hydroxy group with 4-alkoxybenzoic acids resulted in the
synthesis of mesogenic 3-aryl-3-keto ester used to produce copper(II) metallomesogenic complexes.
DOI: 10.1134/S1070363213080148
Among many types of liquid-crystal compounds it
is accepted to define a new class of mesomorphic
metallocomplexes as metallomesogens [1–4]. Over the
past 20 years an intensive research has been performed
on the synthesis of metallomesogens and the study of
their properties. This is due to the specific physical and
chemical properties of metallomesogens that allow
fundamental research of the liquid crystalline state of
matter. Since recently, more studies were carried out to
find the possibilities of practical application of metallo-
mesogens. For example, metallomesogens were suggested
as components of the optical glass with desired proper-
ties [4], components of liquid crystal mixtures for
luminescent displays [5], and stationary phase in gas
chromatography [6, 7].
3-ketopropanoates and the corresponding copper(II)
complexes based on synthesized 3-aryl-3-ketoesters
[13, 14] appropriate for testing this assumption. While
determining the phase transition temperatures of the
synthesized metallocomplexes we found that these
compounds do not have the liquid crystal properties
[14]. The absence of liquid crystal properties is most
likely due to the insufficient number of rings in the
hard scaffold of the molecules of these compounds.
The best way to increase the number of rings in the
scaffold of mesogenic 3-ketoesters, in our opinion, is
to synthesize 3-(4-benzoyloxyphenyl)-3-ketopropanoates.
In the compounds of this type the benzene rings are
bound with a bridging ester group. It is known that
bridging groups in the hard scaffold of a metallo-
mesogen molecule extend temperature limits of
existence of the mesophase. This fact is known for
many types of metallomesogenic complexes derived
from 1,3-dicarbonyl chelating ligands [1–3, 10].
Therefore, we believed that a simultaneous increase in
the number of rings and introduction of bridging
groups in the mesogenic 3-ketoesters might improve
the mesomorphic properties of the corresponding metallo-
complexes.
To produce metallomesogens for application as
ligands various 1,3-bifunctional organic compounds
are often used [1–3]. For example, well-known ligands
for coordination mesomorphic compounds are 1,3-
diketones [1–5, 8, 9].
In carrying out targeted research on the synthesis of
metallomesogenic complexes [10–12] and analyzing
published data we noted that at present the metallo-
mesogens based on 3-ketoesters remain unknown.
These substances are structurally related to 1,3-di-
ketones widely used as ligands in the preparation of
metallomesogens. We believe that it is logical to
expect the possibility of preparation of new types of
metallomesogens on the basis of 3-ketoesters.
For the synthesis of metallomesogenic complexes
based on 3-aryl-3-ketoesters with bridging groups in
the hard scaffold it seemed necessary to obtain the 3-
(4-hydroxyphenyl)-3-oxopropanoic acid (IV), contain-
ing a free phenol hydroxy group. The starting com-
pound was 4-acetoxybenzoic acid (I). The 4-acet-
oxybenzoyl chloride (II) obtained in the first stage
Previously we obtained homologous 3-(4-al-
koxyphenyl)-3-ketopropionates, 3-(4'-pentylbiphenyl)-
1556

1557
SYNTHESIS OF NEW METALLOMESOGENS BASED ON 3-KETOESTERS
from the acid I by treatment with thionyl chloride was
used without purification for the acylation of ethyl
acetoacetate. The reaction was carried out in the
presence of magnesium chloride and pyridine [15].
The resulting (4-acetoxybenzoyl)acetoacetate (III) was
subjected to cleavage by the action of aqueous
ammonia in the presence of ammonium chloride. In
these conditions not only the Hunsdiecker’s splitting
proceeded, but hydrolysis of acetate protecting group
also occurred. This sequence of operations resulted in
ethyl 3-(4-hydroxyphenyl)-3-oxopropanoate IV with a
free phenol group in a total yield of 32%.
O
O
O
O
O
O
O
OEt
AcO
AcO
AcO
OEt
OH
Cl
I
II
III
O
RO
O
O
OH
O
O
O
O
HO
RO
OEt
DCC, DMAP
OEt
IV
Va-Vg
EtO
O
O
OR
O
O
O
O
Cu
O
RO
O
OEt
VIа−VIg
R = С3H7 (а), С4H9 (b), С5H11 (c), С6H13 (d), С7H15 (e), С8H17 (f), С9H19 (g). DCC is N,N'-dicyclohexylcarbodiimide,
DMAP is N,N'-dimethylaminopyridine.
The structure of compound IV was proved by the
spectral data. The UV spectrum of this substance
exhibits an absorption maximum at 283 nm, which
corresponds to the absorption of substituted aromatic
ring. The IR spectrum of this compound contains
strong vibration bands of the O-H group in the region
of 3000–3600 cm–1 confirming the removal of the
acetate protecting group in the reaction with aqueous
ammonia. In the region of vibrations of the carbonyl
group there are two strong bands at 1736 and 1673 cm–1,
which correspond to two C=O groups of the ketoester
IV. At the successful splitting according to Huns-
diecker hydrolysis of phenol ester occurs, while the 3-
keto ester is not affected. This is confirmed by the fact
that in the 1H NMR spectrum of the ketoester IV there
is no singlet of the acetyl group with intensity cor-
responding to three protons. At the same time, the
proton signals of ethoxy group of the ethyl ester
remains in the 1H NMR spectrum: a triplet at δ 1.19 ppm
and a quartet at δ 4.12 ppm.
In the 1H NMR spectrum of compound IV there is a
doublet of the aromatic ring protons and a two-proton
singlet of C2H2 group at δ 3.00 ppm. These data
confirm the 3-aryl-3-ketoester structure of compound
IV.
Further we synthesized a series of esters, Va–Vg,
by esterification of phenol IV with 4-alkoxybenzoic
acids in the presence of dicyclohexylcarbodiimide and
dimethylaminopyridine. The structure of benzoates
Va–Vg was confirmed by spectral studies. In the IR
spectra of all esters the characteristic vibration bands
of the O-H are absent. The IR spectra of homologous
esters contain three strong bands of the characteristic
vibrations of the C=O groups, for compound Va at at
1
1730, 1689, and 1627 cm–1. In the H and 13C NMR
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1558
V. KOVGANKO, N. KOVGANKO
spectra of the benzoates Va–Vg there are the signals of
the IR spectra of the synthesized compounds VIa–VIg
indicates the absence of coordinated water or alcohol
in these complexes. These data are consistent with the
data of elemental analysis on the percentage of copper
in the resulting complexes.
3-aryl-3-ketoester fragment and the carboxylate
1
residues (Table 1). According to the H NMR spectra,
the compounds Va–Vg are mixtures of tautomers with
predominance of the keto form (4:1). Thus, for the
enol forms of the compounds Va–Vg in the proton
spectrum there is a characteristic singlet of the vinyl
proton C2H at δ 5.82 ppm and a broad singlet of the
proton of OH group at δ 12.65 ppm.
Mesomorphic properties of the synthesized
compounds. Investigation of phase transitions in the
synthesized compounds showed that the β-ketoesters
Va–Vg are characterized by the mesomorphism. These
compounds form mainly the monotropic smectic
phase. We found the existence in benzoate Vf of a
thermotropic smectic phase A, in benzoate Va, a
monotropic nematic phase. The formation of
mesophases by two-ring mesogens with different 1,3-
bifunctional groups has been found previously [18,
19]. The liquid-crystalline state in these materials is
likely stabilized due to the formation of additional
quasi-cycle with involvement of the 1,3-bifunctional
group [18, 19].
In the synthesis of metallomesogens with 1,3-
bifunctional ligands the process of complex formation
with bivalent metals capable of forming flat square
complexes is most often used. Such coordination
ensures planarity of the chelate unit, which is
important for obtaining substances with liquid crystal
properties [1, 10, 11]. As complexing agents for the
metallomesogens with 1,3-bifunctional ligands the ions
of copper(II), nickel(II), palladium(II) and other metals
were suggested [1-10].
We synthesized mesogenic complexes VIa–VIg
containing bridging ester groups in the hard scaffold of
molecules by the reaction of β-ketoesters Va–Vg with
copper(II) acetate. The complexes are dark green
crystalline substances, readily soluble in benzene,
chloroform, ethyl acetate and sparingly soluble in
alcohol. The structures of the synthesized compounds
were confirmed by IR and UV spectra and elemental
analysis (Table 2).
In the study of phase transitions of the synthesized
chelates VIa–VIg we found that for compounds VIa
and VIb only the transition to isotropic liquid phase is
typical. Increasing the number of carbon atoms in the
alkoxide chain of the mesogenic molecules led to
stabilization of complexes VIc–VIg in liquid crystal-
line state. Moreover, these compounds are charac-
terized by the formation of a nematic phase. This fact
is quite important, as most of the known columnar
metallomesogens are characterized by smectic meso-
morphism [1–3], which largely limits their application.
The UV absorption spectra of the complexes VIa–
VIg contain an absorption maximum at 270-277 nm.
The absorption maxima positions do not differ from
those in the spectra of the initial β-ketoesters Va–Vg.
Most likely, they correspond to the absorption of
aromatic fragment of the ligand.
As mentioned above, the copper(II) complexes with
3-(4-alkoxyphenyl)-3-ketoester
and
3-(4-pentyl-
biphenyl)-3-ketoesters [14] do not form liquid crystal
phases. The introduction of an additional benzene ring
and the bridging of the ester group in the rigid scaffold
of the molecule increases mesogenic ability of the
chelating 3-ketoesters VIb–VIg, which affects
positively the mesomorphic properties of the corres-
ponding metallocomplexes.
The IR spectra of compounds VIa–VIg contain the
bands of stretching vibrations of the benzoate C=O
bond at 1730-1720 cm–1. The conjugated system of the
bonds of the chelate ring induces a number of strong
bands in the region of 1600-1460 cm–1. Among other
well-identifiable characteristic vibration bands in the
IR spectra of chelates VIa–VIg, for example, vibration
bands of C-H bonds of the aromatic and alkyl
substituents in the region of 3100–2850 cm–1 and C–O
bonds at 1260– 1160 cm–1 can be specified. In the
synthesis, isolation, and preparation of analytical
samples of the copper(II) complexes VIa–VIg we used
water and various alcohols. These agents are known
[16, 17] to be sometimes included in the complex
compounds. The lack of absorption bands of O–H in
Thus, we established that the mesogenic 3-keto-
esters can be used as chelating ligands in the
preparation of metallomesogens.
EXPERIMENTAL
IR spectra were recorded in the region of 400–4000
cm–1 from tablets with potassium bromide on a Nicolet
FTIR Nexus spectrometer, UV spectra from ethanol
solutions were taken on a Specord M500 spectro-
photometer. NMR spectra were recorded on a Bruker
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SYNTHESIS OF NEW METALLOMESOGENS BASED ON 3-KETOESTERS
Table 1. Physicochemical characteristics of 3-ketoesters Va–Vg
Comp.
no.
Yield,
%
Phase transition
temperature, °Са
UV spectrum,
IR spectrum,
1H NMR spectrum, δ, ppm
(J, Hz)b
13C NMR spectrum,
δ, ppm
R
λmax, nm
ν, cm–1
С3Н7
73
Cr 71 I
270
3077, 2965, 2930,
2871 (С–Н), 1730,
1689, 1627 (С=О),
1606, 1576, 1505
1.04 t (3H, CH3, J 7), 1.82 10.60, 14.23 (CH3);
sextet (2Н, CH2, J 7), 4.02 t 22.96 (CH2); 46.06
(2H, ОCH2C2H5, J 7), 1.21 (C2H2 ketone); 61.37,
t (3H, CH3, J 7) 4.15 q (2Н, 70.19 (ОCH2); 87.58
ОCH2CH3, J 7), 4.03 s (2Н, (=С2Н, enol) 114.94,
C2H2), 7.04 d (2H, Ar, J 9), 121.97, 122.70, 128.03,
7.36 d (2H, Ar, J 9), 8.04 d 130.69, 132.86, 134.61,
Vа
(I 65 N 55 SmA 50 Cr)
(С=Сarom
)
(2H, Ar, J 9), 8.12 d (2H,
Ar, J 9)
155.85 (Сarom); 164.31,
164.39, 168.00, 191.95
(C=О, С3, ketone, enol)
С4Н9
91
Cr 85 I
270
3118, 3061, 2921,
2870, 2854 (С–Н),
1727, 1685, 1627
0.99 t (3H, CH3, J 7) 1.50
14.00, 14.23 (CH3);
Vb
(I 77 SmA 57 Cr)
sextet (2Н, CH2, J 7), 1.79 19.72, 31.73 (CH2);
quintet (2Н, CH2, J 7), 4.07 46.08 (C2H2, ketone);
(С=О), 1608, 1580, t (2H, ОCH2C3H7, J 7),
1514 (С=Сarom 1.21 t (3H, CH3), 4.15 q
61.41, 68.48 (ОCH2);
87.61 (=С2Н, enol);
)
(2Н, ОCH2CH3, J 7), 4.04 s 114.98, 121.96, 122.72,
(2Н, C2H2), 7.04 d (2H, Ar, 128.05, 130.71, 132.87,
J 9), 7.36 d (2H, Ar, J 9),
134.62, 155.87 (Сarom);
8.04 d (2H, Ar, J 9), 8.12 d 164.36, 164.44, 168.07,
(2H, Ar, J 9)
192.05 (C=О, С3,
ketone, enol)
С5Н11 73
Cr 84 I
271
3113, 3062, 2955,
2871 (С–Н), 1728,
1647, 1619 (С=О),
1607, 1579, 1513
0.94 t (3H, CH3, J 7), 1.36– 14.20, 14.23 (CH3);
1.50 м (4Н, CH2), 1.81 22.97, 28.74, 29.38
quintet (2Н, CH2, J 7), 4.06 (CH2); 46.07 (C2H2,
t (2H, ОCH2C4H9, J 7). ketone); 61.38, 68.74
1.21 t (3H, CH3, J 7), 4.15 (ОCH2); 88.01 (=С2Н,
q (2Н, ОCH2CH3), 4.03 s enol); 114.95, 121.99,
(2Н, C2H2), 7.03 d (2H, Ar, 122.70, 128.05, 130.70,
J 9), 7.36 d (2H, Ar, J 9), 132.88, 134.64, 155.86
8.04 d (2H, Ar, J 9), 8.12 d (Сarom); 164.32, 164.41,
Vc
(I 76 SmC 70 Cr)
(С=Сarom
)
(2H, Ar, J 9)
167.99, 191.94 (C=О,
С3, ketone, enol)
С6Н13 70
Cr 92 I
276
3111, 3060, 2931,
2869 (С–Н), 1728,
1685, 1620 (С=О),
1607, 1579, 1513
0.92 t (3H, CH3, J 7), 1.30– 14.22 (CH3); 23.13,
1.40 м (4Н, CH2), 1.48 26.26, 29.65, 32.16
Vг
(I 87 SmA 68 Cr)
quintet (2Н, CH2, J 7), 1.80 (CH2); 46.07 (C2H2,
quintet (2Н, CH2, J 7), 4.06 ketone); 61.40, 68.76
(С=Сarom
)
t (2H, ОCH2C5H11, J 7),
(ОCH2); 87.60 (=С2Н,
1.21 t (3H, CH3, J 7), 4.15 enol); 114.96, 121.95,
q (2Н, ОCH2CH3, J 7), 4.04 122.72, 128.05, 130.71,
s (2Н, C2H2), 7.03 d (2H,
Ar, J 9), 7.36 d (2H, Ar, J (Сarom); 164.35, 164.42,
132.87, 134.62, 155.86
9), 8.04 d (2H, Ar, J 9),
8.12 d (2H, Ar, J 9)
168.05, 192.03 (C=О,
С3, ketone, enol)
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V. KOVGANKO, N. KOVGANKO
Table 1. (Contd.)
Yield,
Phase transition
temperature, °Са
UV spectrum,
IR spectrum,
1H NMR spectrum, δ, ppm
(J, Hz)b
13C NMR spectrum,
Comp.
no.
R
%
λmax, nm
ν, cm–1
δ, ppm
С7Н15 82
Cr 95 I
270
3120, 3062, 2956,
2944, 2925, 2856
0.93 t (3H, CH3, J 7), 1.33– 14.26 (CH3); 23.14,
1.45 м (6Н, CH2), 1.50 26.56, 29.65, 29.69,
Ve
(I 89 SmA 83 Cr)
(С–Н), 1728, 1648, quintet (2Н, CH2, J 7), 1.83 32.38 (CH2); 46.06
1621 (С=О), 1606,
quintet (2Н, CH2, J 7), 4.08 (C2H2, ketone); 61.36,
1580, 1513
t (2H, ОCH2C6H13, J 7), 68.75 (ОCH2); 87.58
(С=Сarom
)
1.23 t (3H, CH3, J 7), 4.17 (=С2Н, enol); 114.94,
q (2Н, ОCH2CH3, J 7), 4.05 121.96, 122.70, 128.03,
s (2Н, C2H2), 7.05 d (2H,
130.69, 132.85, 134.61,
Ar, J 9), 7.38 d (2H, Ar, J 155.85 (Сarom); 164.30,
9), 8.06 d (2H, Ar, J 9),
8.14 d (2H, Ar, J 9)
164.40, 167.98, 191.93
(C=О, С3, ketone, enol)
С8Н17 82
Cr 87 SmA 92 I
270
3113, 3062, 2955,
2871 (С–Н), 1728,
1647, 1619 (С=О),
1607, 1579, 1513
0.90 t (3H, CH3, J 7), 1.25– 14.23, 14.27 (CH3);
1.43 м (8Н, CH2), 1.48 23.17, 26.61, 29.70,
Vf
quintet (2Н, CH2, J 7), 1.80 29.84, 29.95, 32.41
quintet (2Н, CH2, J 7), 4.06 (CH2); 46.07 (C2H2,
(С=Сarom
)
t (2H, ОCH2C7H15, J 7),
ketone); 61.36, 68.75
1.21 t (3H, CH3, J 7), 4.15 (ОCH2); 87.58 (=С2Н,
q (2Н, ОCH2CH3, J 7), 4.03 enol); 114.94, 121.97,
s (2Н, C2H2), 7.03 d (2H,
Ar, J 9), 7.36 d (2H, Ar, J 132.86, 134.63, 155.85
122.70, 128.03, 130.69,
9), 8.04 d (2H, Ar, J 9),
8.12 d (2H, Ar, J 9)
(Сarom); 164.30, 164.40,
167.98, 191.93 (C=О,
С3, ketone, enol)
С9Н19 75
Cr 101 I
270
3106, 3061, 2921,
2853 (С–Н), 1727,
1684, 1630 (С=О),
1609, 1580, 1514
0.89 t (3H, CH3, J 7), 1.25– 14.23, 14.28 (CH3);
1.40 м (10Н, CH2), 1.48 23.17, 26.59, 29.70,
Vg
(I 97 SmA 72 Cr)
quintet (2Н, CH2, J 7), 1.80 29.84, 29.98, 30.13,
quintet (2Н, CH2, J 7), 4.06 32.45 (CH2); 46.07
(С=Сarom
)
t (2H, ОCH2C8H17, J 7),
(C2H2, ketone); 61.36,
1.21 t (3H, CH3), 4.15 q
68.75 (ОCH2); 87.58
(2Н, ОCH2CH3, J 7), 4.03 s (=С2Н, enol); 114.95,
(2Н, C2H2), 7.03 d (2H, Ar, 121.99, 122.69, 128.03,
J 9), 7.36 d (2H, Ar, J 9),
130.69, 132.86, 134.63,
8.04 d (2H, Ar, J 9), 8.12 d 155.86 (Сarom); 164.30,
(2H, Ar, J 9)
164.41, 167.97, 191.91
(C=О, С3, ketone, enol)
a
Here and hereinafter Cr is crystal phase; N is nematic phase; SmA, SmC are smectic phase of A or C type; I is isotropic liquid phase. In
parentheses the type of phase transitions and temperature of monotropic transitions are given. b Proton signals given correspond to the
keto form of 1,3-dicarbonyl compound Va–Vg.
Avance 500 instrument (operating frequency 500.13 MHz
bench connected to the polarizing microscope.
Determining the mesophase type was performed by
comparing the observed textures with appropriate
references [20]
1
for H and 125.75 MHz for 13C) from solutions in
deuterodioxane. Chemical shifts are given relative to
TMS as internal reference. The reaction course and
purity of the compounds was monitored by TLC on
Merck Kieselgel 60 F254 plates. The melting points
and phase transitions were determined on a heating
Ethyl 3-(4-hydroxyphenyl)-3-oxopropanoate (IV).
To a heterogeneous mixture of 12.10 g (0.127 mol) of
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SYNTHESIS OF NEW METALLOMESOGENS BASED ON 3-KETOESTERS
Table 2. Physicochemical characteristics of metallocomplexes VIa–VIg
Yield,
%
Phase transition
temperature, °Са
UV spectrum,
Found Cu, %/
Comp.
no.
IR spectrum,
R
ν, cm–1
λmax, nm
Calculated Cu, %
3074, 2977, 2933, 2878 (С–Н), 1730 (С=О,
ester), 1604, 1575, 1538, 1510, 1497 (С=О,
С=С, С=Сarom), 1166, 1197, 1267 (С–О)
Cr 218 I
С3Н7
84.5
80
276
270
271
270
277
270
269
8.00/7.92
VIа
VIb
VIc
VId
VIe
VIf
(decomp.)
2958, 2931, 2872 (С–Н), 1728, (С=О, ester),
1604, 1575, 1542, 1510, 1498 (С=О, С=С,
С=Сarom), 1164, 1199, 1268 (С–О)
Cr 219 I
С4Н9
С5Н11
С6Н13
С7Н15
С8Н17
С9Н19
8.07/7.65
7.37/7.40
7.33/7.17
6.84/6.95
7.21/6.74
6.64/6.55
(decomp.)
3072, 2960, 2942, 2871 (С–Н), 1724 (С=О,
ester), 1606, 1577, 1545, 1512, 1498 (С=О,
С=С, С=Сarom), 1163, 1199, 1261 (С–О)
Cr 223 I
93
(I 166 N 151 Cr)
2929, 2862 (С–Н), 1725 (С=О, ester), 1606,
1577, 1541, 1514, 1497 (С=О, С=С,
С=Сarom), 1162, 1196, 1263 (С–О)
85
Cr 209 N 220 I
Cr 196 N 211 I
Cr 179 N 203 I
Cr 173 N 196 I
3066, 2936, 2865 (С–-Н), 1732 (С=О, ester),
1603, 1580, 1569, 1531, 1511, 1494 (С=О,
С=С, С=Сarom), 1162, 1194, 1257 (С–О)
91
2924, 2856 (С–Н), 1726 (С=О, ester), 1605,
1580, 1531, 1510, 1495 (С=О, С=С,
С=Сarom), 1162, 1193, 1258 (С–О)
84
2923, 2851 (С–Н), 1721 (С=О, ester), 1605,
1576, 1534, 1513, 1497 (С=О, С=С,
С=Сarom), 1165, 1199, 1257 (С–О)
88
VIg
magnesium chloride and 14.6 ml (0.115 mol) of ethyl
acetoacetate in 270 ml of methylene chloride at
cooling to 5°C under vigorous stirring was added
dropwise 10.0 ml of pyridine. The resulting reaction
mixture was stirred with cooling in ice bath for 40 min.
Then a solution of acetoxybenzoyl chloride II, prepared
from 20.67 g (0.115 mol) of 4-atcetoxybenzoic acid I
and an excess of thionyl chloride, in 40 ml of
methylene chloride was added dropwise. The reaction
mixture was stirred for 2.5 h with cooling in ice bath,
left overnight at room temperature and then diluted
with 250 ml of water. The organic layer was separated,
the aqueous layer was extracted with methylene
chloride. The combined organic extracts were washed
with water. Methylene chloride was distilled off under
a reduced pressure. The residue containing aroyl-
acetoacetic ether III was dissolved in 100 ml of
ethanol. To this solution 30 ml of water, 30 ml of 25%
ammonia solution, and 8.06 g (0.151 mol) of
ammonium chloride was added. The reaction mixture
was kept at room temperature for 4 h and then treated
in succession with 30 ml of concentrated hydrochloric
acid and 100 ml of water. Organic compound was
repeatedly extracted with toluene. The toluene solution
was washed with water and then passed through a
column with alumina. Eluting with toluene separated
most of the impurities (TLC control). The main pro-
duct was isolated eluting with ethyl acetate and petro-
leum ether (1:3). The resulting solution was further
purified by boiling with activated charcoal. After
removal of the solvent in vacuo 7.6 g of oily β-keto-
ester IV was obtained, yield 32%. UV spectrum (λmax
,
nm): 283. IR spectrum, ν, cm–1 (the film between KBr
plates): 3000-3600 br (OH), 2983, 2940 (C–H), 1736,
1
1673 (C=O), 1604, 1583, 1515 (C=Sar.). H NMR
spectrum, δ, ppm: 1.19 t (3H, J 7 Hz, CH3), 3.00 s (2H,
COCH2CO), 4.12 q (2H, J 7 Hz, OCH2), 6.81 d (2H, J
8.5 Hz), 7.84 d (2H, J 8.5 Hz), aromatic protons.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 8 2013

1562
V. KOVGANKO, N. KOVGANKO
3. Binnemans, K. and Gorller-Walrand, C., Chem. Rev.,
Ethyl 3-[4-(4'-propoxy)benzoyloxyphenyl]-3-oxo-
2002, vol. 102, no. 6, p. 2303.
4. Hudson, S.A. and Maitlis, P.M., Chem. Rev., 1993,
vol. 93, no. 3, p. 861.
5. Binnemans, K. and Moors, D., J. Mater. Chem., 2002,
no. 12, p. 3374.
6. Chen, J.-L. and Liu, C.-Y., J. Chromatog. (A), 2007,
propanoate (Va). To a mixture of 0.52 g (2.89 mmol)
of 4-propoxybenzoate, 0.55 g (2.64 mmol) of phenol
IV, and 0.60 g (2.91 mmol) of N,N'-dicyclo-hexyl-
carbodiimide in 20 ml of methylene chloride was
added in a catalytic amount N,N-dimethylaminopyri-
dine. The reaction mixture was stirred for 25 h. The
precipitate of dicyclohexylurea was removed by filtra-
tion through a layer of aluminum oxide, the sorbent
was then washed additionally with methylene chloride.
The combined filtrate was evaporated under a reduced
pressure, the residue was recrystallized from 2-
propanol. The yield of ester Va 0.66 g (73%).
vol. 1161, nos. 1–2, p. 269.
7. Huang, K.-P., Kumar Misra, T., Wang, G.-R., Huang, B.-Y.,
and Liu, C.-Y., J. Chromatog. (A), vol. 1215, nos. 1–2,
2008, p. 177.
8. Serrano, J.L. and Sierra, T., Chem. Eur. J., 2000, vol. 6,
no. 5, p. 759.
9. Date, R. and Bruce, D., Liq. Cryst., 2004, vol. 31,
Compound Vb–Vg were obtained by similar
procedure. The properties of esters Va–Vg are shown
in Table 1.
no. 11, p. 1435.
10. Kauhanka, U.M. and Kauhanka, М.M., Liq. Cryst.,
2006, vol. 33, no. 2, p. 213.
11. Kovganko, V.N., Kovganko, N.N., Turanova, О.А.,
Frolova, Е.N., and Turanov, А.N., Coord. Khim., 2010,
vol. 36, no. 4, p. 289.
Copper(II)
bis-{1-ethoxy-3-[4'-(4''-propyloxy-
benzoyl)phenyl]propane-1,3-dionate} (VIa). To a
solution of 0.203 g (0.549 mmol) of β-ketoester Va in
10 ml of 2-propanol under reflux while stirring was
added 0.075 g (0.375 mmol) of copper(II) acetate
monohydrate. The stirring under reflux was continued
for 20 min, then 5 ml of water was added. After
15 min, the dilution with water (10 ml) was repeated,
and the mixture was stirred under reflux for 10 min.
The precipitated complex compound was filtered off,
washed successively with 2-propanol, a mixture of 2-
propanol and water (1:1), and then with water. After
drying in air and in a vacuum 0.186 g of compound
VIa was obtained. Yield 84.5%. To obtain an
analytical sample the material was recrystallized from
a mixture of chloroform and 2-propanol.
12. Kovganko, V.N. and Kovganko, N.N., Zh. Org. Khim.,
2006, vol. 42, no. 3, p. 442.
13. Kovganko, V.N. and Kovganko, N.N., and Polovkov, М.А.,
Zh. Org. Khim, 2010, vol. 46, no. 12, p. 1803.
14. Kovganko, V.N. and Kovganko, N.N., Vest. Nat. Akad.
Nauk Belarusi, Ser. Khim., 2012, no. 2, p. 88.
15. Clay, R.J., Collom, T.A., Karrick, G.L., and Wemple, J.,
Synthesis, 1993, no. 3, p. 290.
16. Casas, J.S., Castano, M.V., Garcia-Tasende, M.S.,
Sanchez, A., Sоrdo, J., and Touceda, A., Polyhedron,
2005, vol. 24, p. 3057.
17. Casas, J.S., Castano, M.V., Castellano, E.E., Ellena, J.,
Garcia-Tasende, M.S., Gato, A., Sanchez, A., San-
juan, L.M., and Sordo, J., Inorg. Chem., 2002, vol. 41,
no. 6, p.1550.
Compounds VIc–VIg were obtained by similar
procedure. Properties of chelates VIa–VIg are shown
in Table 2.
18. Pociecha, D., Krowczyński, A., Szydłowska, J., Go-
recka, E., Glogarova, M., and Przedmojski, J., J. Mater.
Chem., 1997, vol. 7, no. 9, p. 1709.
REFERENCES
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20. Demus, D. and Richter, L., The Texture of Liquid
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2. Gimenez, R., Lydon, D.P., and Serrano, J.L., Curr.
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 8 2013