Solvent extraction of Ag(I) and Cu(II) with new macrocyclic Schiff bases

Article abstract of DOI:10.1002/jccs.201100465

Two new macrocyclic Schiff bases (II) and (III) containing nitrogen - oxygen donor atoms were synthesized by reaction between diethylene triamine or 2,2'-(ethylenedioxy)bis(ethylamine) and the intermediate compound: 1,4-bis(6-methoxy-2-formylphenyl)-1,4-d

Full text of DOI:10.1002/jccs.201100465

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
Solvent Extraction of Ag(I) and Cu(II) with New Macrocyclic Schiff Bases
Souad Kedy,* Farouk Kandil and Nadeem Almhna
Department of Chemistry, Faculty of Science, Damascus university, Syria
(Received Jul. 28, 2011; Accepted Sept. 27, 2011; Published Online Oct. 21, 2011; DOI: 10.1002/jccs.201100465)
Two new macrocyclic Schiff bases (II) and (III) containing nitrogen - oxygen donor atoms were synthe-
sized by reaction between diethylene triamine or 2,2¢-(ethylenedioxy)bis(ethylamine) and the intermedi-
ate compound: 1,4-bis(6-methoxy-2-formylphenyl)-1,4-dioxabutane (I). Identification of these macro-
cyclic Schiff bases: 1,12, 15,18, 29,32 - hexaaza - [3,4;8,9;20,21;26,27-tetra-(6¢-methoxyphenyl)]-
5,8,22,25-tetraoxa cyclo tetratriacosine-1,11,18,28-tetraene. (II) 1,12,21,32-tetraaza-[3,4;9,10;23,24;29,
30-tetra-(6¢-methoxyphenyl)]-5,8,15,18,25,28,35,38-octaoxa cyclo - tetracontane-1,11,21,31-tetraene.
(III) were determined by elemental analysis (LC-MS), (IR) and (1H and 13C-NMR) spectroscopy. The liq-
uid-liquid extraction of metal picrates such as Ag+ and Cu2+ fromaqueous phase to organic phase was car-
ried out using these ligands. The effect of chloroform and dichloromethane as organic solvents over the
metal picrate extractions were investigated at 25 0.1 °C by using atomic absorption spectrometer.
Keywords: Macrocyclic Schiff bases; Liquid-liquid extraction.
INTRODUCTION
Polyaza macrocycles with large cavities have re-
choose the correct template metal ion or to predict certain
ring contraction reactions were the template cation dose
not coordinate with all of the ring nitrogen atoms.8 In some
cases, reduction of the cyclic Schiff base and removal of
the template ion have been difficult.9 A non template
method for the formation of macrocyclic poly Schiff bases
has also been studied. This procedure often gave a poly-
meric material beside cyclization reaction, while there is no
need to remove a metal ion.10 In the present work we used a
non template method for the formation of two novel macro-
cyclic Schiff bases having ethoxy groups: (II) and (III)
Scheme I, then were used for removel of various metal ions
from the aqueous phase in to the organic phase in liquid-
liquid extraction system.
ceived recent interests as inorganic cation receptors. The
cyclic arrangement of a large number of donor atoms and
the flexibility of these ligands make them good hosts for
ion complexes.1,2 They were also used as spectrophotomet-
ric analytical reagents. Metal ions have enormous impor-
tance in many biological processes, especially heavy metal
ions are effective enzyme inhibitors exerting toxic effects
on living system.3 Therefore, separation and determination
of toxic metal ions such as mercury, lead, and cadmium in
environmental sources play an important role for healthy
life. Although new macrocyclic compounds containing ox-
ygen, sulfur, and nitrogen are knowing. Macrocyclic com-
pounds used in solvent extraction were mostly the oxygen
donar type.4 Anumber of methods for the preparation of the
large polyaza macrocyclic have been reported. The most
common synthetic procedure requires the use of N-tosyl
groups to protect and activate the nitrogen atoms in the
cyclization step.5 Ring closure occurs by a condensation re-
action of N-tosylated polyamines with the appropriate
ditosylate ester or dihalide in DMF in the presence of base.6
These reactions allow the production of polyaza macro-
cycles in moderate yields, but removing the N-tosyl groups
requires drastic conditions and is not always straightfor-
ward.7 Another cyclization process uses the template ring
closure for formation of cyclic di- or tetra dental Schiff
base. This is a simple process, but it is often difficult to
EXPERIMENTAL
Materials and method
Chloroform, dichloromethane, dimethyl formamide,
picric acid, methanol, K2CO3, Cu(NO3)2.3H2O, Ag(NO3),
were the analytical grade reagents and were purchased
from Merck. Diethylene triamine, 2,2¢-(ethylenedioxy)bis-
(ethylamine), 1,2-dibromoethane and o-vanillin were re-
cord from sigma-Aldrich. IR spectra was obtained on Jusco
300 FT-IR Spectrometer using KBr discs. Mass spectra of
the ligand were carried out on a micro mass Quattro LC-
MS/MS Spectrometer. 1H-NMR and 13C-NMR spectra was
recorded at ambient Broker DT-400 Spectrometer using
CDCl3 with DMSO-DMF as the internal standard. A Hita-
* Corresponding author. E-mail: souadkdyi@yahoo.com
J. Chin. Chem. Soc. 2012, 59, 525-528
© 2012 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
525

Article
Kedy et al.
Structure of the macrocyclic Schiff bases
(II), and (III)
C=C), 1287, 1238 (aromatic-O), 1220 (O-CH3), 1180,
1130 (R-O), 756 (substituted benzene). 1H and 13C-NMR
spectra in CDCl3are complex.12
Scheme I
1H-NMR (CDCl3-d6): 8.78 (s, 4H, CH=N), 6.74-7.62
(m, 24H, Ar–H), 4.72 (t, 4H, -CH2-NH-), 3.90, 3.97 (t, 4H,
CH2-O-ph), 3.70, 3.77, 3.78, 3.80 (t, 4H, CH2-O-), 2.29,
2.26 (s, 12H, O-CH3), 13C-NMR (CDCl3-d6, d ppm):
OCH3: 56.72, 57.03, 57.95, NH-CH2: 69.65, 67.71, OCH2:
73.03, 73.72. Aromatic: 111.99, 112.53, 116.25, 117.95,
119.41, 120.91, 122.26, 122.08 128.32, 143.01, 144.14,
156.65, 159.97, HC=N: 169.93, 167.51. Anal. Calc. For
C44H54N6O8: C, 66.5; H, 6.8; N, 10.6. Found: C, 66.4; H,
6.9; N, 10.9; [a] D20.5 = 1.62.
Synthesis of 1,12,21,32-tetraaza-[3,4;9,10;23,24;29,30-
tetra-(6¢-methoxyphenyl)]-5,8,15,18,25,28,35,38-
octaoxacyclo-tetracontane-1,11,21,31-tetraene (III)
The macrocyclic compound (III) was prepare by the
dropwise addition of solution of the 2,2¢-(ethylenedioxy)
bis(ethylamine) (0.74 g, 5 mmol) in methanol (60 mL) to a
stirred solution of compound (I) (1.66 g, 5 mmol) in metha-
nol (60 mL). After the addition was completed, the stirring
was continued for 10 h, an oily product began to separate
from solution . It was purified by washing with ethanol, the
large macrocyclic product pal yellow oil. Yield: (2.6 g,
60%), Mass spectra: m/z = 882 [III-2H]+. IR (KBr pellets,
cm-1): 3026 (aromatic–CH), 2888-2847 (Aliphatic-C-H),
1650 (CH=N). 1488-1460 (aromatic C=C), 1287, 1238 (ar-
omatic-O), 1222 (O-CH3), 1180, 1130 (R-O), 754 (substi-
chi Model 180-80 Atomic absorption Spectrometer (acety-
lene/air flame) was used to determine the concentration of
metal ions.
Synthesis of 1,4-bis(6-methoxy-2-formylphenyl)-1,4-
dioxabutane (I)
To a stirred solution of o-vanillin (3.04 g, 0.02 mol)
and K2CO3 (1.38 g, 0.01 mol) in DMF (50 mL) 1,2-dibro-
moethane (1.88 g, 0.01 mol) in DMF (10 mL) was added
dropwise the reaction was continued for 10 h at 150-155 °C
and then 5 h at room temperature after the addition was
completed, 20 mL distilled water was added it was left in
refrigerator for 1 h later the precipitate was filtered, washed
by 50 mL water, dried in air, re-crystallized from ethanol.11
Colour: bright brown. m.p: 180-182 °C. Yield: (4.6, 70%),
Mass spectra: m/z = 330; IR (KBr pellets, cm-1): 3003 (aro-
matic-CH), 2930-2887 (Aliphatic-C-H), 1700 (C=O)str,
1482-1475 (aromatic C=C), 1289, 1311 (Ar-O), 1181 (O-
CH3), 1130, 1100 (R-O), 757 (substituted benzene).
Synthesis of 1,12,15,18,29,32-hexaaza-[3,4;8,9;20,21;
26,27-tetra-(6¢-methoxyphenyl)]-5,8,22,25-tetraoxa-
cyclotetratriacosine-1,11,18,28-tetraene (II)
1
tuted benzene). H and 13C-NMR) spectra in CDCl3 are
complex.12 1H-NMR (CDCl3-d6): 8.52 (s, 4H, CH=N),
7.10-7.74 (m, 12H, Ar–H), 4.31-4.5 (t, 8H, O-CH2-CH2),
3.97 (t, 4H, O-CH2-), 3.89 (t, 4H, CH2-O-ph), 2.41 (s, 12H,
O-CH3). 13C-NMR (CDCl3-d6, d ppm): OCH3: 40.15, CH2-
O-Ph: 69.35, 69.03, 66.72, OCH2: 70.32, 71.91, 72.54,
73.26, 74.97, 75.49, Aromatic: 102.91, 111.08, 122.26,
122.32, 124.01, 134.14, 136.65, 139.97, 149.51, 150.93,
HC=N: 166.15, 167.27. Anal. Calc. For C48H60N4O12: C,
20.5
65.1; H, 6.8; N, 6.3; Found: C, 65.4; H, 7.1; N, 6.0; [a]D
The macrocyclic compound (II) was prepared by the
dropwise addition of solution of the diethylene triamine
(0.206 g, 2 mmol) in methanol (40 mL) to a stirred solution
of compound (I) (0.66 g, 2 mmol) in methanol (60 mL), the
stirring was continued for 10 h, an oily product began to
separate from solution. It was purified by washing with eth-
anol. The large macrocyclic product pal yellow oil. Yield:
(1.0 g, 64%); Mass spectra: m/z = 795 [II+H]+. IR (KBr pel-
lets, cm-1): 3200 (–N-H), 3080 (aromatic–CH), 2920-2847
(Aliphatic -C-H), 1640 (CH=N)str, 1488-1460 (aromatic
= 1.88.
Solvent extraction
Transition metal picrates were prepared by the step-
wise addition of a 1 × 10-2 M of metal nitrate solution to a
1.25 × 10-4 M aqueous picric acid solution and shaking at
25 °C for 1 h. An organic solution (5 mL) of the ligand
(1.25 × 10-5 M) and an aqueous solution (5 mL) containing
metal picrate (1.25 × 10-4 M) were shacked for 1 h. The re-
sulting mixtures were allowed to stand for at least 1 h in or-
526
www.jccs.wiley-vch.de
© 2012 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2012, 59, 525-528

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Extraction of Ag(I) with Schiff Bases
der to complete the phase separation. The concentred of
cation in aqueous phase was determined by atomic absorp-
tion spectro photometer. The extractability was calculated
according to (1).
hexaaza-[3,4;8,9;20,21;26,27-tetra-(6¢-methoxyphenyl)]-
5,8,22,25-tetraoxacyclotetratriacosine-1,11,18,28-tetraen.
(II) was synthesized by reaction of 1,4-bis(6-methoxy-2-
formylphenyl)-1,4-dioxa butane (I), with diethylene tri
amine in methanol. The IR spectrum of the ligand (II)
shows a peak due to n (CH=N)str at 1640 cm-1, a peak due to
n (–N-H) at 3200 and the absence of a peak due to n (C= O)
at around 1700 cm-1 for the (I) is indicative of Schiff base
condensation. The mass spectra show a molecular peak at
m/z= 330 for (I) and m/z = 792 for (II) are confirmed the
formation of macrocyclic Schiff base (II) 1,12,21,32-tetra-
aza-[3,4;9,10;23,24;29,30-tetra-(6¢-methoxyphenyl)]-
5,8,15,18,25,28,35,38-octaoxacyclo-tetracontane-1,11,
21,31-tetraene. (III) was synthesized by reaction of 1,4-
bis(6-methoxy-2-formylphenyl)-1,4-dioxabutane(I)
with-2,2¢-(ethylene dioxy)bis(ethylamine) in methanol.
The IR spectrum of ligand (III) shows a n (CH=N)str peak at
1650 cm-1 and the absence of a peak due to n (C= O) at
around 1700 cm-1 for the (I) is indicative of Schiff base
condensation.13 The mass spectra show a molecular peak at
m/z = 882 for (III) and m/z = 330 for (I) are confirmed the
formation of macrocyclic Schiff base (III).
% E = [(A0-A)/A0] × 100
(1)
where A0 is the concentration of cation in aqueous phase
before extraction.
Ais the concentration of cation in aqueous phase after
extraction. The dependence of the distribution ratio D of
the cation between the aqueous phase and the organic phase
upon the ligand concentration was examined.
The general extraction equilibrium is given by equa-
tion (2)
Mn+aq + npic-aq + m Lorg = [M(Pic)n(L)m]org
(2)
The overall extraction equilibrium constant is expressed as
equation (3)
[M(Pic)n(L)m]org
Kex = ¾¾¾¾¾¾¾¾¾¾
org
(3)
[Mn+]aq [pic-]naq [L] m
Extraction of metal picrates
The distribution ratio D would be defined by equation (4)
[M(Pic)n(L)m]org
Table (1) shows the extractability of Ag+ and Cu2+
picrates from the aqueous phase into organic phase by
macrocyclic Schiff bases (II) and (III). It is clear that the
extractability results of the macrocyclic Schiff bases are
different for both of the organic solvents, when dichloro-
methane was used as organic solvent macrocyclic (II) ex-
tracted Ag+ ion 78.0% but the other metal ions not ex-
tracted effectively. Macrocyclic (III) extracted Ag+ ion
89.2% for the same solvent. It is interesting that the per-
centage of the extraction of the metal ions with macrocyclic
(III) is higher than of macrocyclic(II) for both of the sol-
vents.These results is suggested that the phenyl group is the
efficient group in the extraction and increasing a number of
oxygen donor increases the percentage of the extraction of
the metal ions. It can be seen from Table (1) that the solvent
has an important effect upon the cation extractability.
These results may depend on dielectric constants the sol-
vents. The dielectric constants of dichloromethane and
chloroform are 9.1 and 4.8 respectively. Dichloromethane
having a high dielectric constants is favored for the extrac-
tion of all the metal ions there are similar results in litera-
ture.14 On the other hand, the better solvation of the com-
plexes by dichloromethane may be a valuable reason for
better extraction. From the extraction data shown in Table
D = ¾¾¾¾¾¾¾¾
(4)
[Mn+]aq
It follows that
D = Kex [pic-]naq [L] m org
(5)
(6)
LogD = nlog[Pic] + log Kex + m log[L]
The extraction aquilibrium constant (log Kex) between an
aqueous solution of metal picrates and an organic solution
of (Schiff base cation) complex can be calculated from
equation (6).
RESULT AND DISCUSSION
Macrocyclic Schiff bases
In this work, we have found that in the reaction be-
tween diethylene triamine or 2,2¢-(ethylenedioxy)bis(eth-
ylamine) and dialdehyde (I) the (2:2) Schiff base macro-
cycle is formed as the major product. The macrocyclic lig-
ands were characterized by mass spectrometry, IR and 1H
and 13C NMR spectroscopy. The mass spectra of (II) and
(III) play an important role in conforming the (2:2) (di-
aldehydes:diamine). Macrocyclic Schiff 1,12,15,18,29,32-
J. Chin. Chem. Soc. 2012, 59, 525-528
© 2012 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.jccs.wiley-vch.de
527

Article
Kedy et al.
Table 1. The extractability of aqueous metal picrates for macro-
cyclic Schiff bases (II) and (III) in to organic phase at
25.0 0.1 °C
observed. The slope of equal to 1 suggesting the ligand (III)
forms a (1:1) (L:M) for Cu2+ complexe with ligand (III).
The slope of equal to 2 suggesting the ligand (III) forms a
(1:2) (L:M) for Ag+ complexe with ligand (III).
Extractabilitya,b
(II) (III)
%
Extractabilitya,c
(II) (III)
%
Metal Ion
Ag+
78.0 0.3 89.2 0.1 22.4 0.1 42.2 0.3
25.1 0.2 34.1 0.3 8.1 0.3 21.4 0.2
CONCLUSION
Cu2+
A noval macrocyclic Schiff bases (II) and (III) have a
good extraction abillity of Ag+ ion from the aqueous phase
to the dichloromethane phase.
But it was observed a high extraction of Ag+ ion with
macrocyclic Schiff base (III) wich has N4O8 donor sets than
of macrocyclice (II) wich has N6O4 donor sets. It was found
that macrocyclices have N6O4, N4O8 donor sets extracted
Ag+ compared with the other transition metal cations Cu2+
as selective.
a Aqueous phase (5 mL); [pic] = 1.25 × 10-5 M,
Organic phase (5 mL), [L] = 1.25 × 10-4 M
b Defined as percent extracted in to dichloromethane phase
c Defined as percent extracted in to chloroform phase
Table 2. The selectivity of silver picrate over the other metal
picrates for macrocyclic Schiff
a,b
n+
/ Dm
n+
Selectivity
D
Selectivitya,c DAg+/ Dm
Ag+
Metal ion
Cu2+
(II)
(III)
(II)
(III)
2.3 0.2
The composition of extracted complexes (L:M) is 2:1
when M = Ag+ and 1:1 when M = Cu2+ for the ligand (III).
9.1 0. 2 12.4 0.3
4.8 0.3
b Calculated for dichloromethane as organic phase
c Calculated for chloroform as organic phase
ACKNOWLEDGEMENTS
We are grateful to Department of Chemistry, Faculty
of Science, Damascus university, Syria for the support of
this research.
(1). It is clear that the ligands which have N6O4, N4O8, do-
nor sets show that both of the cation-cavity size and the
type of binding sites in the ring contribute to the ability of
Ag+ ion binding.
REFERENCES
1. Krzysztof, E.; Krakowiak, S.; Kent, D.; Geng, W. J. Org.
Chem. 1991, 56, 8.
Table (2) shows the selectivity of silver picrate over
the other metal picrate for macrocyclic Schiff bases(II) and
(III). The selectivity is indicated as DAg+ / Dmn+. DAg+ and
Dmn+ denotes the distribution ratio of Ag+ ion and Mn+ ion
respectively. Macrocyclic Schiff bases (II) and (III) indi-
cated high selective extraction of Ag+ ion over the, Cu2+ ion
with 12.4, respectively. The selectivity results for to di-
chloromethane are higher than those for chloroform.
Fig. 1 shows the extraction into dichloromethane at
different concentration of ligand from 1 × 10-5 M to 1.5 ×
10-4 M. A liner relationship between Log D versus Log L is
2. Scott, C.; Sally, B. Inorg. Chem. 2011, 50, 3697.
3. Christian, G.-D. Pharm. Anal. 1996, 14, 889.
4. Ummuhan, O.; Hakan, A. Sep. Sci. Technol. 2006, 41, 401.
5. Walkowiak, W.; Brown, P.-R.; Shukla, P.; Bartsch, R.-A. J.
Membr. Sci. 1987, 32, 59.
6. Iwata, M.; Kuzuhara, H. Bull. Chem. Soc. Jpn. 1989, 62, 198.
7. Ibrahim, U.; Ismet, B.; turgut, K.; Umit, C. J. Heterocycl.
Chem. 2006, 43, 1679.
8. Beckmann, U.; Brooker, S. Coord. Chem. Rev. 2003, 17,
245.
9. Drew, M.-J.; Murphy, B.-P.; Nelson, S. M. J. Chem. Soc.,
Dalton Trans. 1987, 873.
10. Sone, T.; Ohba, Y.; Watanabe, R. Bull. Chem. Soc. Jpn. 1989,
62, 1346.
11. Salih, I.; Hamid, T. J. Mol. Struct. 2008, 891, 157.
12. Antoni, L.; Joseph, R.; Arthur, M.; Inorg. Chem. 1994, 33,
5946.
13. Salih, I.; Hamid, T. Spectrochim. Acta A- Mol. Biomol. Spec.
2008, 69, 903.
Fig. 1. Log D versus Log L for the extraction of Ag-
14. Ziyadonogullari, B.; Topal, G. Talanta 2001, 53, 10834.
picrate (n) and Cu-picrate (s).
528
www.jccs.wiley-vch.de
© 2012 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2012, 59, 525-528