Synthesis and characterization of Salamo-type bisoxime compounds based on 2-hydroxy-4-methoxybenzaldehyde and bis(aminooxy)alkane

Article abstract of DOI:10.14233/ajchem.2014.17568

There new Salamo-type bisoxime compounds H₂L¹-H₂L³ have been synthesized from 2-hydroxy-4-methoxybenzaldehye and 1,5-bis(aminooxy)pentane, 1,6-bis(aminooxy)hexane or 1,9-bis(aminooxy)nonane in hot ethanol medium, respectivel and characterized by elemental analysis, IR and ¹HNMR spectroscopy.

Full text of DOI:10.14233/ajchem.2014.17568

Asian Journal of Chemistry; Vol. 26, No. 18 (2014), 6269-6271
ASIAN JOURNAL OF CHEMISTRY
http://dx.doi.org/10.14233/ajchem.2014.17568
Synthesis and Characterization of Salamo-Type Bisoxime Compounds
Based on 2-Hydroxy-4-methoxybenzaldehyde and Bis(aminooxy)alkane
*
LI WANG , WEI-MIN ZHOU, GANG LI and YANG ZHANG
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, P.R. China
*
Corresponding author: E-mail: wangli_78@126.com; kkil615@yahoo.com.cn
Received: 7 March 2014;
Accepted: 15 May 2014;
Published online: 1 September 2014;
AJC-15896
1
3
2 2
Three new Salamo-type bisoxime compounds H L -H L have been synthesized from 2-hydroxy-4-methoxybenzaldehyde and 1,5-
bis(aminooxy)pentane, 1,6-bis(aminooxy)hexane or 1,9-bis(aminooxy)nonane in hot ethanol medium, respectively and characterized by
1
elemental analysis, IR and H NMR spectroscopy.
Keywords: Salamo-type compound, Synthesis, Characterization.
INTRODUCTION
ethanolic solution (10 mL) of 2-hydroxy-4-methoxybenzal-
dehyde (304.3 mg, 2 mmol) was added an ethanolic solution
Particular attention has been paid in recent years to the
(
6 mL) of 1,5-bis(aminooxy)pentane (134.2 mg, 1 mmol). The
synthesis, characterization and application of Salen-type
1
compounds . The new Salen-type bisoxime compounds have
reaction mixture was stirred at 328 K for 5 h. The formed
precipitate was separated by filtration and washed successively
very important value that they are widely used in catalytic
2
3,4
domain , medical field , analytical chemistry , material
5
with ethanol/n-hexane (1:4). The product was dried under
1
L .
6,7
vacuum to obtain white title compound H
2
world , etc. So we devoted to design and synthesis of a series
of new Salamo-type bisoxime compounds which have far-
reaching significance. In the present study we have designed
and synthesized three new Salamo-type bisoximes, named as
O
C
O
C
O
C
n
Br
Br
2 2 2
NH NH ·H O
n
n
H
2
N
O
O
NH2
2
N OH
N O O N
C
O
C
C
O
5
,5'-dimethoxy-2,2'-[(pentane-1,5-diyldioxy)bis-(nitrilo-
1
O
2
methylidyne)]diphenol (H L ), 5,5'-dimethoxy-2,2'-[(hexane-
1
L : n = 4; H
2
L : n = 5;
Fig. 1. Synthetic route to bis(aminooxy)alkane. H
3
L : n = 8
2
2
2
L ) and
1
5
,6-diyldioxy)bis(nitrilo-methylidyne)]diphenol (H
,5'-dimethoxy-2,2'-[(nonane-1,9-diyldioxy)bis-(nitrilo-
2
H
2
3
2
methylidyne)]diphenol (H L ).
O
N
O
N
EXPERIMENTAL
OHC
OH
2
-Hydroxy-4-methoxybenzaldehyde (≥ 99 %), 1,5-
2
CH
3
CH
2
OH
dibromopentane (97 %), 1,6- dibromohexane (97 %) and 1,9-
dibromononane (97 %) were purchased and used without
further purification. Other reagents were analytical pure grade
and purchased from Tianjin Chemical Reagent Factory. The
+
H
2
N
O
O
NH
2
OH
HO
5
5°C
OMe
MeO
OMe
1
2
Fig. 2. Synthetic route to the Salamo-type bisoxime compound H L
8,9
others are the same as literature .
General procedure: Synthetic route to Salamo-type
Preparation of 5,5'-dimethoxy-2,2'-[(hexane-1,6-
2
diyldioxy)bis(nitrilomethylidyne)]diphenol (H L ): To an
1
3
2
2 2
bisoxime compounds H L -H L are shown in Fig. 1-4. 1,5-
ethanolic solution (6 mL) of 2-hydroxy-4-methoxybenzal-
dehyde (194.5 mg, 1.28 mmol) was added an ethanolic solution
(10 mL) of 1,6-bis(aminooxy)hexane (81.1 mg, 0.64 mmol).
The reaction mixture was stirred at 328-333 K for 6 h. The
formed precipitate was separated by filtration and washed
bis(aminooxy)pentane, 1,6-bis(aminooxy)hexane or 1,9-
bis(aminooxy)nonane were synthesized according to an
7
analogous method reported earlier .
-9
Preparation of 5,5'-dimethoxy-2,2'-[(pentane-1,5-
1
L ): To an
diyldioxy)bis(nitrilomethylidyne)]diphenol (H
2

6
270 Wang et al.
Asian J. Chem.
1
L are soluble
successively with ethanol/n-hexane (1:4). The product was
ethanol, insoluble in n-hexane. In addition, H
3
2
2
L .
dried under vacuum to obtain white title compound H
2
in dichloromethane and acetonitrile, but H
2
L are insoluble in
1
L and
dichloromethane and just soluble in hot acetonitrile. H
2
3
L are easy to be dissolved in ethyl ether and acetic ether,
H
2
2
O
N
O
N
2
but H L are difficult to be dissolved in ethyl ether, simulta-
CHO
neously, it can't be dissolved in acetic ether.
IR spectra: The most important IR spectral data for
OH
+
CH CH
3
2
OH
2
1
3
H
2
N
O
O
NH
2
OH
HO
5
5°C
Salamo-type bisoxime compounds H
2 2
L -H L are given in
Table-2. In the IR spectrum of Salamo-type bisoxime
1
MeO
OMe
2
-1
OMe
2
compound H L , 2950 and 2879 cm are the weak absorption
2
Fig. 3. Synthetic route to the Salamo-type bisoxime compound H L
peaks for both antisymmetric and symmetric stretching vibra-
tion absorption of C-H bond of methylene. In the IR Spectrum
Preparation of 5,5'-dimethoxy-2,2'-[(nonane-1,9-
3
diyldi-oxy)bis(nitrilomethylidyne)]diphenol (H L ): To an
2
2
L , it contains νO-H
of Salamo-type bisoxime compound H
2
bond, but no corresponding peaks were observed near 3600
ethanolic solution (5 mL) of 2-hydroxy-4-methoxybenzal-
dehyde (159.5 mg, 1.05 mmol) was added an ethanolic solution
-1
cm , while at 3169 and 3072 cm , there exists strong broad
-1
absorption peaks, indicating that Salamo-type bisoxime
2
L may have freedom intramolecular hydrogen
(
5 mL) of 1,9-bis(aminooxy)nonane (99 mg, 0.52 mmol). The
compound H
2
reaction mixture was stirred at 328 K for 8 h. The formed
precipitate was separated by filtration under reduced pressure
and washed successively with ethanol/n-hexane (1:4). The
-1
bond (OH···N and OH···O) and at 2945 and 2879 cm , the
weak absorption peak can be attributed to the antisymmetric
and symmetric stretching vibration absorption of C-H bond
product was dried under vacuum to obtain white powder com-
from methylene. Similarly, infrared spectrum of Salamo-type
3
L contains broad absorption peak at
3
L .
pound H
2
bisoxime compound H
2
-1
3431 and 3161 cm also shows that the Salamo-type bisoxime
3
2
compound H L may contain an intramolecular hydrogen bond
O
N
O
N
(OH···N). The anti-symmetric and symmetric methyl stretching
vibration absorption peak of C-H bond presented at 2989 and
CHO
OH
-1
2
852 cm which was very weak.
CH CH
3
2
OH
O
NH
2
OH
HO
2
+
H
2
N
O
55°C
Meanwhile, the characteristic C=N stretching bands of
1
3
2 2
the Salamo-type bisoximes H L -H L appear at 1609-1606
MeO
OMe
OMe
3
L
-1
cm , respectively . And the Ar-O stretching bands occur at
10
Fig. 4. Synthetic route to the Salamo-type bisoxime compound H
2
-1
225, 1223 and 1211 cm for the Salamo-type bisoximes H
1
L -
1
2
3
2
H L , indicating that 2-hydroxy-4-methoxybenzaldehyde has
RESULTS AND DISCUSSION
been condensated with 1,5-bis(aminooxy)penpane, 1,6-
bis(aminooxy)hexane or 1,9-bis(aminooxy)nonane, respec-
1
3
2 2
Three Salamo-type bisoxime compounds H L -H L have
11
tively and formed new Salamo-type bisoximes . In the 1572-
been synthesized with good yields and the compositions are
1
confirmed by elemental analyses, IR, UV-visible and H NMR
-1
1441 cm region, the observed bands were attributed to aromatic
C=C vibrations. IR spectral results of the Salamo-type bisoximes
further confirmed the accuracy of the consequence. So in this
research we have successfully synthesized the target compounds,
spectroscopy.
Physico-chemical property: The colour, yields, melting
points and elemental analytical results of the synthesized
1
2
3
1
3
2 2 2
H L , H L and H L .
2 2
Salamo-type bisoxime compounds H L -H L are presented
1
1
H NMR spectra: The H NMR spectral data of the Salamo-
in Table-1. Their compositions agree with the formulae. All
the compounds are stable in air and soluble in chloroform,
tetrahydrofuran, acetone, DMF, DMSO and hot methanol or
1
L -H
3
L in the solvent of CDCl
type bisoxime compounds H
1
are shown in Table-3. The H NMR analytical results are
2
2
3
TABLE-1
COLOUR, YIELDS, MELTING POINTS AND ANALYTICAL DATA OF
1
SYNTHESIZED SALAMO-TYPE BISOXIME COMPOUNDS H L -H L
3
2
2
Elemental analysis (%): Found (Calcd.)
Compound
Colour
m.p. (K)
Yield (%)
m.f.
m.w.
C
H
N
1
H L
2
White
White
White
349-350
349-350
465-467
51.8
46.5
32.3
C H N O
6
402.44
416.47
458.55
62.79 (62.67)
63.78 (63.45)
65.63 (65.48)
6.68 (6.51)
6.91 (6.78)
7.79 (7.47)
6.83 (6.96)
6.68 (6.73)
6.07 (6.11)
21 26
2
2
H L
2
C H N O
22 28 2 6
3
H L
2
C H N O
25 34 2 6
TABLE-2
KEY IR BANDS (cm ) FOR THE SALAMO-TYPE BISOXIME COMPOUNDS H L -H L
–
1
1
3
2
2
Compound
1
ν(O-H)
3435
ν(CH2)
ν(C=N )
1606
ν(C=C)benzene ring
1568, 1506, 1467
1572, 1505, 1464
1568, 1505, 1441
ν(Ar-O)
1225
H L
2
2950, 2879
2945, 2879
2989, 2852
2
H L
2
3443
1626
1223
3
L
H
2
3431
1609
1211

Vol. 26, No. 18 (2014)
Compound
Synthesis and Characterization of Salamo-Type Bisoxime Compounds 6271
TABLE-3
1
THE H NMR DATA FOR THE SALAMO-TYPE BISOXIME COMPOUNDS H L -H L
1
3
2
2
1
H NMR (400 MHz, CDCl , δ/ppm)
3
1
2.79 (s, 6H, CH
.8 Hz, 2H, PhH), 8.17 (s, 2H, N=CH), 9.94 (s, 2H, OH)
2.13 (t, J = 6.6 Hz, 2H, CH ), 3.64 (s, 6H, CH ), 4.26 (t, J = 6.20 Hz, 10H, CH
2.4 Hz, 2H, PhH), 7.06 (S, 2H, PhH), 8.09 (s, 2H, N=CH), 10.02 (s, 2H, OH)
2.02 (t, J = 6.6 Hz 2H, CH ), 3.81 (s, 18H, CH , CH -O ), 4.26 (t, J = 6.20 Hz, 4H, CH
2.62 Hz, 2H, PhH), 6.98 (s, 2H PhH), 8.09 (s, 2H, N=CH), 12.12 (s, 2H, OH)
2
), 4.41 (s, 10H, CH -O, CH -O), 6.46 (d, J = 2.8 Hz, 2H, PhH), 6.47 (dd, J = 8.4 Hz, 2.6 Hz, 2H, PhH), 7.04 (d, J =
2
3
H L
2
8
2
2
2
-O, CH -O), 6.46 (d, J = 2.4 Hz, 2H, PhH), 6.50 (s, J
2 3
H L
2
=
3
2
2
3
2
-O), 6.57 (d, J = 2.8 Hz, 2H, PhH), 6.58 (d, J
2
H L
=
consistent with the elemental analytical results and the synthe-
3
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1