Synthesis and complex-forming properties of N-substituted diazacrown ethers

Article abstract of DOI:10.1023/B:RUGC.0000025154.24958.66

N-Substituted mono- and diazacrown ether with ethoxycarbonylmethyl, 7-phenyl-3,6-dioxaheptyl, p-methoxy, and p-nitrobenzyl groups in the side chain have been synthesized. Their reactions with alkali and alkaline-earth metals have been studied. Substituent

Full text of DOI:10.1023/B:RUGC.0000025154.24958.66

Russian Journal of General Chemistry, Vol. 73, No. 12, 2003, pp. 1919 1924. Translated from Zhurnal Obshchei Khimii, Vol. 73, No. 12, 2003,
pp. 2029 2034.
Original Russian Text Copyright
2003 by Luk’yanenko, Basok, Kulygina, Vetrogon.
Synthesis and Complex-Forming Properties
of N-Substituted Diazacrown Ethers
N. G. Luk’yanenko, S. S. Basok, E. Yu. Kulygina, and V. I. Vetrogon
Bogatskii Physicochemical Institute, National Academy of Sciences of Ukraine, Odessa, Ukraine
Received December 10, 2001
Abstract N-Substituted mono- and diazacrown ether with ethoxycarbonylmethyl, 7-phenyl-3,6-dioxaheptyl,
p-methoxy, and p-nitrobenzyl groups in the side chain have been synthesized. Their reactions with alkali and
alkaline-earth metals have been studied. Substituents affect the complex-forming ability of the base macro-
cycle by changing the basicity of the nitrogen atoms and coordinating with the complexing ion.
Complex formation of mono- and divalent cations
with lariate crown ethers has been intensively studied
from the very discovery of the latter [1]. The complex-
forming capacity of the latter depends both on the
macrocyclic ligand and on the side chains that can
additionally coordinate with the cation [1 8]. In
general, side chains much affect most properties of the
base macroring, such as conformation, electronic
properties of binding centers and their steric acces-
sibility, etc.. On the other hand, flexible side chains
containing heteroatoms can embrace cations, thus
forming cryptand-like 3D structures [2, 6 8]. As a
result, unusual complex-forming properites arise,
which are not directly related to the concept of size
compatibility of cation and macroring cavity but
strongly depend of the nature of the side chains.
available on their complex formation with alkali and
alkaline-earth cations, which prevents substantiated
conclusions as to the electronic and structural effects
of substituents on the complex-formation reaction.
The main purposes of the present work were to
synthesize a series of N-substituted aza- and diaza-
crown ethers and to study their complex-forming
properties and the effect of the substituents on them.
The target azacrown ethers were prepared by alkyla-
tion of mono- and diazacrown ethers with benzyl
chlorides (compounds VII XII and XVII XIX) or
(7-phenyl-3,6-dioxaheptyl) toluenesulfonate (com-
pounds XV and XVI), or ethyl chloroacetate (com-
pounds XIII, XIV, XX, and XXI). The alkylations
were performed in the presence of sodium carbonate
or triethylamine in boiling acetonitrile or ethanol over
the course of 12 16 h. The yields of pure target pro-
ducts were 73 96%. Azacrown ethers VII and XIV
XX we obtained for the first time. The composition
and structure of the synthesized compounds were
Comprehensive assessment of the effect of side
chains is quite an intricate problem, and molecular
design of lariate crown ethers has so far remained
empirical.
1
At present lariate crown ethers are rather well
studied. At the same time, limited information is
proved by elemental analysis, H NMR spectroscopy,
and mass spectrometry.
m
m
O
O
MeCN or EtOH/Na CO or Et N
2
3
3
NH + RX
N R
Y
Y
O
O
n
n
I VI
VII XXI
Y = O (I III, VII XVI), NH (IV VI), NR (XVII XXI); n = m = 1 (I, IV, VII, X, XVII, XX); n = 1, m = 2 (II, V, VIII,
XI, XIII, XV, XVIII); n = m = 2 (III, VI, IX, XII, XIV, XVI, XIX, XXI); R = 4-O NC H CH (VII IX), 4-MeOC H
2
6
4
2
6 4
CH (X XII, XVII XIX), EtOCOCH (XIII, XIV, XX, XXI), PhCH OCH CH OCH CH (XV, XVI).
2
2
2
2
2
2
2
+
The protonation and complex-formation constants
were determined by pH-metric titration in methanol
respective of the ring size, exhibit K -selectivity in
2
+
2+
the series of alkali metals and Sr - or Ba -selectivity
at 25 C. The resulting data are summarized in Table 1. in the series of alkaline-earth metals. Exceptions are
Lariate diazacrown ether VII XXI almost all, ir- N-(ethoxycarbonylmethyl)aza-15-crown-5 (XIII) and
1
070-3632/03/7312-1919$25.00 2003 MAIK Nauka/Interperiodica

1920
LUK’YANENKO et al.
3
Table 1. Protonation and stability constants of complexes (log K; K, dm /mol) of N-substituted mono- and diazacrown
ethers VII XXI with alkali and alkaline-earth metals in methanol at 25 C
Comp.
no.
H+
Li+
Na+
K+
Rb+
Cs+
Ca2+
Sr2+
Ba2+
a
a
a
VII 8.30 0.01
VIII 7.93 0.01
<1.5
<1.5
<1.5
2.0 0.2
2.05 0.06
2.47 0.03
<1.5
1.8 0.2
<1.5
2.20 0.08 2.01 0.08
2.50 0.06 2.56 0.02
5.04 0.02 5.10 0.03
2.02 0.09 2.05 0.07 2.2 0.2
3.70 0.02 3.60 0.02 2.8 0.1
IX
X
8.04 0.01
1.5 0.1 3.00 0.03 4.52 0.01
a
10.06 0.01
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
a
XI
9.95 0.01
2.80 0.04 2.70 0.03
2.28 0.09 2.96 0.04 3.25 0.05
a
XII 9.80 0.02
XIII 7.80 0.02
XIV 8.11 0.02
1.9 0.1 3.40 0.02 4.68 0.02
2.1 0.1 4.01 0.05 3.77 0.03
1.80 0.02 4.31 0.04 5.36 0.04
1.5 0.3 4.13 0.03 4.34 0.02
1.8 0.2 4.26 0.02 5.76 0.02
3.84 0.02 3.70 0.04 3.25 0.04 5.87 0.02 5.90 0.01
3.19 0.03 2.85 0.01 4.27 0.01 5.29 0.07 5.18 0.03
4.43 0.03 3.69 0.05 5.60 0.03 7.41 0.04 7.50 0.03
3.61 0.04 3.11 0.02 3.52 0.02 5.16 0.03 5.10 0.01
5.04 0.01 4.47 0.06 4.2 0.02 6.58 0.06 7.32 0.01
a
a
a
a
a
XV
10.01 0.02
XVI 10.11 0.04
XVII 10.29 0.01
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
<1.5
7
.11 0.03b
a
XVIII 10.21 0.01 1.90 0.10 2.85 0.03 3.29 0.07
<1.5
<1.5
2.83 0.01 3.30 0.04 3.20 0.04
b
7
.57 0.02
a
b
a
b
a
XIX 9.79 0.01
.09 0.02
9.08 0.01
.74 0.02
XXI 7.85 0.01
1.88 0.01 2.85 0.03 3.35 0.02
<1.5 4.63 0.07 3.74 0.01
2.2 0.1 5.02 0.01 5.34 0.01
2.35 0.04 2.51 0.07 2.92 0.07 5.21 0.04 4.88 0.03
1.9 0.1 <1.5 6.79 0.01 6.83 0.01 6.52 0.01
8
XX
4
3.96 0.02 3.08 0.04 7.70 0.02 9.15 0.04 8.78 0.03
4.48 0.03c 5.49 0.05c 5.06 0.05c
5
.81 0.03b
a
b
Logarithms of the protonation constants corresponding to the equilibrium L + H+ = LH+. Logarithms of the protonation constants
+
+
2+ c
+
corresponding to the equilibrium LH + H = LH
.
Logarithms of the stability constants corresponding to the equilibrium LH +
2
n+
(n+1)+
M
= LHM
.
N,N -bis(ethoxycarbonylmethyl)diaza-12-crown-4
stituted azacrown ethers, we can use the example of
compounds VIII, IX and XI, XII, whose side groups
are incapable of additional coordination with the com-
plexing cation (Table 2).
+
(XX), which selectively react with Na ions.
The stability of the complexes is determined by
the macroring size and the nature of the side groups.
At the same side groups, the stability of the com-
plexes increases with the ring size of the N-substituted
azacrown ether, from 12- to 15- and further to
Increasing basicity of nitrogen increases the re-
lative stability both of alkali and of alkaline-earth
cation complexes. The strongest effect is observed
18-membered (Table 1).
+
2+
2+
with Na , Sr
and Ba , which enhances the
2
+
2+
2+
2+
Substituents appreciably affect the basicity of the
Sr /Ca - and Ba /Ca -selectivities and attenuates
+
+
nitrogen atoms, which suggests change in the com-
plex-forming properties of the macroring. On the
other hand, side chains containing donor atoms can
react with the complexing cation. Molecular modeling
of the complexes shows that in crown ethers with p-
nitrobenzyl and p-methoxybenzyl side groups such
intramolecular reactions are impossible.
the K /Na -selectivity.
The effect of side groups on the stability of com-
plexes of crown ethers VII XVI is more intricate. At
the same ring size and almost equal basicity, as in
compounds XIII XVI, side chains capable of addi-
tionally coordinating with the complexing cation
enhance stability of both alkali and alkaline-metal
cation complexes (Table 1). Therewith, the strongest
effect in the former complexes is produced by ether
side groups (crown ethers XV and XVI), whereas in
the latter complexes, by ester side groups (compounds
XIII and XIV). This phenomenon is probably ex-
plained by the fact that cations with a high charge
However, more flexible groups, such as ethoxy-
carbonylmethyl and 7-phenyl-3,6-dioxaheptyl, are
readily available for cooperative interaction with the
macroring.
To trace the effect of the basicity of the nitrogen
atoms on the complex-forming properties of N-sub-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 12 2003

SYNTHESIS AND COMPLEX-FORMING PROPERTIES
1921
Table 2. Effect of the basicity of the nitrogen atom in N-substituted monoazacrown ethers VIII, IX, XI, and XII on the
relative stability of their complexes ( log K)
log K
H+
Li+
Na+
K+
Rb+
Cs+
Ca2+
Sr2+
Ba2+
log KXI
log KXII
log KVIII
log KIX
2.02
1.76
0
>0.4
0.80
0.40
0.23
0.16
> 0.5
0.14
> 0.6
0.10
0.08
0.45
0.46
0.83
0.69
0.80
Table 3. Effect of the nature of side chains in N-substituted monoazacrown ethers VIII, IX, and XI XVI on the relative
stability of their complexes ( log K)
log K
log KVIII
H+
Li+
Na+
K+
Rb+
Cs+
Ca2+
Sr2+
Ba2+
log KXIII
log KXIV
log KXV
log KXVI
0.13
0.07
0.06
0.31
>0.6
0.3
0
2.01
1.31
1.33
0.86
1.3
1.2
0.7
>2.1
1.2
0.8
0.1
>1.6
0.8
2.07
2.8
1.24
0.95
2.79
2.37
2.2
2.62
log KIX
log KXI
log KXII
0.84
1.64
1.08
2.4
1.85
1.42
0.1
0.71
Table 4. Relative stability of complexes ( log K) of mono- and diazacrown ethers XI, XII, XIV, XVIII, XIX, and
XXI with the same side groups
log K
log KXI
log KXII
log KXIV
Li+
Na+
K+
Rb+
Cs+
Ca2+
Sr2+
Ba2+
log KXVIII
log KXIX
log KXXI
0.40
0.02
0.40
0.05
0.55
0.71
0.59
1.33
0.02
0.00
1.49
0.47
0.00
1.19
0.61
0.55
0.33
2.10
0.34
0.66
1.74
0.05
1.02
1.28
density prefer to interact with the carbonyl group of
the side chain (Table 3).
EXPERIMENTAL
The melting points were measured in open capilla-
1
Comparison of the stabilities of complexes of
mono- and diazacrown ethers with the same ring size
and substituents (Table 4) shows that replacement of
one oxygen atom in 15-membered crown ether XI by
nitrogen (diazacrown ether XVIII) results in a slight
stability enhancement of complexes with all the ions
studied. By contrast, 18-membered diazacrown ether
XIX forms less stable complexes than monoazacrown
ether XII. Complexes of diazacrown ethers XVIII and
XIX get less stable compared with complexes of
monoazacrown ethers XI and XII as the size of the
cation increases along the series of both alkali and
alkaline-earth metals. An exception are potassium
complexes of crown ethers XI and XVIII. As
concerns 18-membered crown ethers XIV and XXI
which contain in the side chain ethoxycarbonyl groups
capable of additionally coordinating with the com-
plexing ion, diazacrown ether XXI forms more stable
complexes with all the alkaline-earth metal cations,
ries and were not corrected. The H NMR spectra
were run on Bruker AM-200 (200 MHz) and Bruker
AM-250 (250 MHz) spectrometers in CDCl , internal
reference TMS. The mass spectra were obtained on
Varian MAT-112 and MX-1331 instruments with
direct inlet at ionizing energies of 70 and 12 eV. Thin-
layer chromatography was performed on Silufol-
254 plates (Chemapol).
3
All commercial reagents were used as received,
unless otherwise stated. Azacrown ethers I III and
diazacrown ethers IV VI were prepared as described
in [9 11]. 7-Phenyl-3,6-dioxaheptyl p-toluenesul-
fonate was prepared from diethylene glycol mono-
benzyl ether [12] according to [13].
N-(4-Nirobenzyl)azacrown ethers VII IX,
N-(4-methoxybenzyl)azacrown ethers X XII, and
N,N -bis(4-methoxybenzyl)diazacrown ethers
XVII XIX (general procedure). A mixture of
20 mmol of monoazacrown ether or 10 mmol of diaza-
crown ether, 22 mmol of corresponding benzyl chlo-
ride, 45 mmol of powdered sodium carbonate, and
+
+
as well as with Li and Na . Probably, both side
groups are involved in complex formation with these
ions.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 12 2003

1922
LUK’YANENKO et al.
7
1
0 ml of dry acetonitrile was refluxed with stirring for
4 h. After cooling, the precipitate was filtered off,
, ppm: 2.78 t (8H, NCH ), 3.59 m and 3.76 m (18H,
2
OCH , ArCH , and OCH ), 6.81 d (4H, Harom), 7.22 d
2
2
3
and the solvent was removed by rotary evaporation.
The residue was dissolved in 100 ml of chloroform,
and the resulting solution was treated with 5% HCl
(4H, Harom). Found, %: C 69.41; H 8.43; N 6.83.
C H N O . Calculated, %: C 69.54; H 8.27; N 6.76.
2
4
34
2
4
N,N -Bis(4-methoxybenzyl)-4,10-diaza-15-
(
3 20 ml). The combined acidic extracts were made
1
crown-5 (XVIII). Oil. Yield 87%. H NMR spectrum,
ppm: 2.78 t (8H, NCH ), 3.61 m and 3.79 m (22H,
alkaline (pH 10) with concentrated NaOH and then
treated with chloroform (3 50 ml). The extracts were
,
2
OCH , ArCH , and OCH ), 6.81 d (4H, Harom), 7.24 d
2
2
3
dried with MgSO , and the solvent was removed at
4
(
4H, Harom). Found, %: C 68.39; H 8.52; N 6.72.
reduced pressure. Solid residues were recrystallized
from ethanol. Oily residues were treated with hot
hexane (3 40 ml), the solvent was removed, and the
procedure was repeated.
C H N O . Calculated, %: C 68.10; H 8.35; N 6.11.
2
6
38
2
5
N,N -Bis(4-methoxybenzyl)-4,13-diaza-18-
crown-6 (XIX). Colorless crystals. Yield 86 %, mp
1
4
5 47 C. H NMR spectrum, , ppm: 2.78 t (8H,
NCH ), 3.59 m and 3.77 m (26H, OCH , ArCH , and
N-(4-Nitrobenzyl)aza-12-crown-4 (VII). Colorless
1
2
2
2
crystals. Yield 90%, mp 54 56 C. H NMR spectrum,
OCH ), 6.81 d (4H, Harom), 7.22 d (4H, Harom). Found,
3
,
ppm: 2.73 t (4H, NCH ), 3.67 m (14H, OCH ,
2 2
%
%
: C 67.03; H 8.59; N 5.72. C H N O . Calculated,
: C 66.91; H 8.42; N 5.57.
N-(4-Ethoxycarbonylmethyl)azacrown ethers
28 42 2 6
ArCH ), 7.56 d (2H, Harom), 8.12 d (2H, Harom).
2
Found, %: C 58.17; H 7.03; N 9.14. C H N O .
1
5
22
2
5
Calculated, %: C 58.05; H 7.15; N 9.03.
XIII and XIV and N,N -bis(4-ethoxycarbonyl-
methyl)diazacrown ethers XX and XXI (general
procedure). A mixture of 20 mmol of monoazacrown
ether or 10 mmol of diazacrown ether, 22 mmol of
ethyl chloroacetate, and 40 mmol of triethylamine in
N-(4-Nitrobenzyl)aza-15-crown-5 (VIII). Oil.
Yield 89%. H NMR spectrum, , ppm: 2.76 t (4H,
1
NCH ), 3.68 m (16H, OCH ), 3.84 s (2H, ArCH ),
2
2
2
7
5
5
.59 d (2H, Harom), 8.15 d (2H, Harom). Found, %: C
8.51; H 7.23; N 8.02. C H N O . Calculated, %: C
1
7
26
2
6
5
0 ml of ethanol was heated under reflux with stirring
7.61; H 7.39; N 7.90.
for 16 h, cooled, and poured into 200 ml of water.
The resulting solution was treated with chloroform
N-(4-Nitrobenzyl)aza-18-crown-6 (IX). Oil. Yield
1
(
6 20 ml). The combined chloroform extracts were
8
3
8%. H NMR spectrum, , ppm: 2.84 t (4H, NCH ),
2
dried with MgSO , and the solvent was removed at
.69 m (20H, OCH ), 3.85 s (2H, ArCH ), 7.60 d (2H,
4
2
2
reduced pressure. The residue was treated with boiling
hexane (3 25 ml), the solvent was removed at re-
duced pressure, and the residue was distilled in
a vacuum.
Harom), 8.19 d (2H, Harom). Found, %: C 57.18; H
7
7
.68; N 7.21. C H N O . Calculated, %: C 57.27; H
19 30 2 7
.59; N 7.03.
N-(4-Methoxybenzyl)aza-12-crown-4 (X). Oil.
1
N-(Ethoxycarbonylmethyl)aza-15-crown-5
XIII). Oil. Yield 81%, bp 148 151 C (0.05 mm). H
Yield 86%. H NMR spectrum, , ppm: 2.69 t (4H,
NCH ), 3.65 m and 3.78 s (17H, OCH , ArCH , and
1
(
2
2
2
NMR spectrum, , ppm: 1.23 t (3H, CH ), 2.90 t (6H,
OCH ), 6.80 d (2H, Harom), 7.21 d (2H, Harom). Found,
3
3
NCH ), 3.46 s and 3.55 m (16H, OCH ), 4.14 d (2H,
%
%
: C 65.21; H 8.41; N 4.89. C H NO . Calculated,
2
2
1
6
25
4
COCH ). Found, %: C 55.20; H 9.03; N 4.43.
: C 65.06; H 8.53; N 4.74.
2
C H NO . Calculated, %: C 55.07; H 8.91; N 4.59.
1
4
27
6
N-(4-Methoxybenzyl)aza-15-crown-5 (XI). Oil.
1
Yield 89 %. H NMR spectrum, , ppm: 2.70 t (4H,
NCH ), 3.67 m and 3.76 s (21H, OCH , ArCH , and
N-(Ethoxycarbonylmethyl)aza-18-crown-6
1
2
2
2
(XIV). Oil. Yield 77%, bp 172 175 C (0.05 mm). H
OCH ), 6.80 d (2H, Harom), 7.21 d (2H, Harom). Found,
3
NMR spectrum, , ppm: 1.22 t (3H, CH ), 2.92 t (6H,
3
%
%
: C 63.21; H 8.55; N 4.25. C H NO . Calculated,
1
8
29
5
NCH ), 3.47 s and 3.56 m (20H, OCH ), 4.15 d (2H,
2
2
: C 63.69; H 8.61; N 4.13.
COCH ). Found, %: C 54.83; H 9.08; N 3.92.
2
C H NO . Calculated, %: C 55.00; H 8.94; N 4.01.
N-(4-Methoxybenzyl)aza-18-crown-6 (XII). Oil.
16 31
7
1
Yield 92 %. H NMR spectrum, , ppm: 2.74 t (4H,
NCH ), 3.62 m, 3.66 m and 3.76 s (25H, OCH ,
N,N -Bis(ethoxycarbonylmethyl)-4,10-diaza-12-
2
2
crown-4 (XX). Oil. Yield 73%, bp 184 187 C
ArCH , and OCH ), 6.81 d (2H, Harom), 7.23 d (2H,
2
3
1
(
0.05 mm). H NMR spectrum, , ppm: 1.23 t (6H,
Harom). Found, %: C 62.80; H 8.81; N 3.52. C H33
20
CH ), 2.90 t (12H, NCH ), 3.46 s and 3.55 m (8H,
NO . Calculated, %: C 62.64; H 8.67; N 3.65.
3
2
6
OCH ), 4.14 d (4H, COCH ). Found, %: C 55.33; H
2
2
N,N -Bis(4-methoxybenzyl)-4,10-diaza-12-
crown-4 (XVII). Oil. Yield 91%. H NMR spectrum,
8.64; N 8.01. C H N O . Calculated, %: C 55.47;
H 8.73; N 8.09.
16 30 2 6
1
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 12 2003

SYNTHESIS AND COMPLEX-FORMING PROPERTIES
1923
N,N -Bis(ethoxycarbonylmethyl)-4,13-diaza-18-
technique. A combined glass electrode (Ingold)
coupled with an automated titrator (Titrino DMS-716),
at 25 C. The standard internal solution of the re-
ference electrode (saturated aqueous KCl) of the
combined glass electrode was replaced by a 0.01 M
crown-6 (XXI). Oil. Yield 86%, bp 202 205 C
1
(
0.05 mm). H NMR spectrum, , ppm: 1.24 t (6H,
CH ), 2.92 t (12H, NCH ), 3.47 s and 3.56 m (16H,
3
2
OCH ), 4.16 d (4H, COCH ). Found, %: C 55.40; H
2
2
8
.92; N 6.38. C H N O . Calculated, %: C 55.28;
solution of Et NCl in MeOH, saturated with AgCl.
2
0
38
2
8
4
H 8.81; N 6.45.
Parameters (pH and S) of the electrode function
0
+
pHobs = pH + Slog [H ] were determined from the
N-(7-Phenyl-3,6-dioxaheptyl)azacrown ethers
XV and XVI (general procedure). A mixture of
0 mmol of monoazacrown ether, 22 mmol of 7-
phenyl-3,6-dioxaheptyl p-toluenesulfonate, and
5 mmol of powdered sodium carbonate in 80 ml of
dry acetonitrile was heated under reflux with stirring
for 12 h. The mixture was cooled, the precipitate was
filtered off, and the solvent was removed at reduced
pressure. The residue was dissolved in 100 ml of
chloroform and washed with 30 ml of water, saturated
0
titration curve of a 0.001 M solution of HClO in
4
MeOH [obtained by dilution of concentrated (11.6 M)
2
perchloric acid] with a 0.01 M solution of Et NOH in
4
the presence of 0.01 M Et NClO . For methanol
4
4
4
pKMeOH 16.7 was used. The protonation constants
and the complex-formation constants bxyz relating to
+
the overall complex-formation equilibrium (xMn +
+
+
(nx+z)
yL + zH = (M L H
) were determined from the
x
y
z
pH-metric data obtained in the course of neutralization
of the acidic solution of ligand with a 0.01 M solution
NaCl solution (2 30 ml), and dried with MgSO . The
4
solvent was removed at reduced pressure, and the
residue was dissolved in 50 ml of 5% HCl. The result-
ing solution was treated with chloroform (2 20 ml),
made alkaline (pH 10) with concentrated NaOH, and
treated again with chloroform (3 50 ml). The extract
of Et NOH in MeOH under argon in the presence or
4
in the absence of metal salts. Data treatment was per-
formed using the SIRKO program [14] which allows
simultaneous calculation of b , electrode parameters,
xyz
and component concentrations. The overall titration
curve in the range pH 3 12 was used in calculations.
was dried with MgSO , and the solvent was removed
4
at reduced pressure. The residue was treated with
boiling hexane (3 25 ml). The solvent was removed
in a vacuum to leave pure products as thick oils.
The electrode parameters and the stability (b ) and
xyz
protonation (b ) constants obtained by titration of
0
yz
ligands in the absence of metals were set constant at
preliminarily calculated values.
N-(7-Phenyl-3,6-dioxaheptyl)aza-15-crown-5
XV). Oil. Yield 79%. H NMR spectrum, , ppm:
1
(
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2
7
3
.81 m (6H, NCH ), 3.66 m (24H, OCH , ArCH ),
2 2 2
.36 m (5H, Harom). Found, %: C 63.31; H 8.69; N
.45. C H NO . Calculated, %: C 63.45; H 8.87;
1
2
. Izatt, R.M., Bradshaw, J.S., and Nielsen, S.A., Chem.
Rev., 1985, vol. 85, no. 4, p. 271.
2
1
35
6
N 3.52.
. Barbour, L.J., De Wall, S.L., Meadows, E.S., and
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N-(7-Phenyl-3,6-dioxaheptyl)aza-18-crown-6
XVI). Oil. Yield 75%. H NMR spectrum, , ppm:
1
(
2
.78 t and 2.83 t (6H, NCH ), 3.63 m (28H, OCH ,
2 2
ArCH ), 7.30 m (5H, Harom). Found, %: C 62.68; H
2
3. Tsukube, H., Inoue, T., and Hori, K., J. Org. Chem.,
9
.08; N 3.09. C H NO . Calculation, %: C 62.56;
23 39 7
1994, vol. 59, no. 26, p. 8047.
H 8.90; N 3.17.
4
5
6
. Rodopoulus, T., Pittet, P.-A., and Lincoln, S.F.,
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Determination of the protonation and complex-
formation constants of azacrown ethers VII XXI.
The solvent, methanol (Carlo Erba, water content
. Manchanda, V.K., Mohapatra, P.K., and Zhu, C.,
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<0.01 %) was used as received. Solutions of ligands
were obtained by dissolving weighed samples in
methanol. The ionic strengths of the solutions were
. Habata, Y., Saeki, T., Watanabe, A., Akabori, S.,
Jerald, S., and Bradshaw, J.S., J. Heterocycl. Chem.,
2
maintained constant (10 M) by adding tetraethyl-
1
999, vol. 36, no. 2, p. 355.
ammonium perchlorate recrystallized from methanol.
The titrant was a solution of tetraethylammonium
hydroxide obtained by dilution of a commercial solu-
tion (25% in MeOH, Fluka) and standardized against
potassium hydrogen phthalate.
7
8
. Liu, Y., Zhang, H.-Y., Bai, X.-P., Wada, T., and
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Talanova, G.G., Purkiss, D.W., and Rogers, R.D.,
J. Org. Chem., 1999, vol. 64, no. 15, p. 5341.
The stability constants of complexes were deter-
mined potentiometrically by the proton competition
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1924
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. Calverley, M. J. and Dale, J., Acta Chem. Scand.,
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1
1
0. Maeda, H., Nakaisuji, Y., and Okahara, M., J. Chem.
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 12 2003