Synthesis, spectroscopic studies and crystal structure of 1,2-bis (4-nitro benzoyloxy) ethane

Article abstract of DOI:10.1007/s10870-011-0067-x

The dinitro compound, 1,2-bis (4-nitro benzoyloxy) ethane, was synthesized by nucleophilic substitution reaction under inert atmosphere using Schotten-Baumann conditions and characterized by its melting point, elemental analysis, FT-IR, ¹H and

Full text of DOI:10.1007/s10870-011-0067-x

J Chem Crystallogr (2011) 41:1180–1184
DOI 10.1007/s10870-011-0067-x
ORIGINAL PAPER
Synthesis, Spectroscopic Studies and Crystal Structure
of 1,2-bis (4-nitro benzoyloxy) ethane
Muhammad Saif Ullah Khan
•
Michael Bolte
•
Zareen Akhter Humaira M. Siddiqi
•
Received: 28 October 2009 / Accepted: 7 March 2011 / Published online: 22 March 2011
Ó Springer Science+Business Media, LLC 2011
Abstract The dinitro compound, 1,2-bis (4-nitro benzoyl-
oxy) ethane, was synthesized by nucleophilic substitution
reaction under inert atmosphere using Schotten–Baumann
conditions and characterized by its melting point, elemental
properties [3, 4]. One of the possible ways to obtain such
polymers is the incorporation of various flexible segments
like ether moiety [5], sulfone linkage [6] and methylene
spacers [7] etc. in the macrochain by structural tailoring of
monomers. These flexible linkages increase the degree of
freedom by reducing the segmental barrier and effectively
disrupt the potential intermolecular interactions and thus
enhance the solubility and processability of the resulting
polymers [8–10]. Polar ester group (O=C–O) can also be
incorporated in the polymer backbone [11, 12] which brings
about inter and intra-molecular interactions and counter-
balances any loss of thermal properties that is caused by
incorporation of flexible linkages [13, 14]. It is reported that
the presence of both ester group and flexible linkages in the
macrochain favour ordered polymer morphologies and
usually exhibit liquid crystalline behaviour [15–17].
1
13
analysis, FT-IR, H and C-NMR spectroscopic studies. The
structure of the title compound was also determined by single
crystal X-ray crystallography. The compound crystallizes in
the orthorhombic space group Aba2 with cell parameters
˚
a = 33.119(2) A, b = 8.1301(5) A, c = 11.9784(8) A, V =
˚
˚
3
225.3(4) A and Z = 8. The central O–CH –CH –O unit
˚
3
2
2
present in the compound shows a partially eclipsed confor-
mation. The dihedral angle between the two aromatic rings is
o
5.87 (6) . The terminal nitro groups and the bridging ester
4
groups present in the compound are almost coplanar with the
aromatic rings to which they are attached.
Keywords Nucleophilic substitution ꢀ Crystal structure ꢀ
Spectroscopic studies ꢀ Dinitro precursor
The title compound, a flexible dinitro precursor con-
taining built-in ester linkages and methylene spacers
between aromatic units, was prepared as part of our quest
to design and synthesize a series of structurally modified
monomers for processable high performance polymers,
which will be reported elsewhere.
Introduction
The properties of polymers can be improved by inducing
desired modifications in their core structure [1, 2]. Therefore,
considerable research in the recent years has focused upon
producing speciality polymers with a better balance of
Experimental
Chemicals
M. S. U. Khan ꢀ Z. Akhter (&) ꢀ H. M. Siddiqi
4
-Nitrobenzoic acid, ethylene glycol and triethyl amine
Department of Chemistry, Quaid-i-Azam University, Islamabad
45320, Pakistan
e-mail: zareenakhter@yahoo.com
were purchased from Fluka, Switzerland and used without
further purification. Thionyl chloride was obtained from
Merck, Germany and used as received. Toluene was pro-
cured from Panreac, Spain and ethanol was obtained from
Riedel–deHa e¨ n, Germany. The solvents were freshly dried
and distilled prior to use.
M. Bolte
Institut f u¨ r Anorganische Chemie, J.W.Goethe-Universit a¨ t
Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main,
Germany
1
23

J Chem Crystallogr (2011) 41:1180–1184
1181
Fig. 1 FTIR spectrum of
synthesized dinitro compound
Synthesis of p-Nitrobenzoyl Chloride
Measurements
p-Nitrobenzoyl chloride was synthesized according to the
method already reported by our group [19].
The elemental analysis was performed using CHNS-932
LECO instrument. Melting temperature was determined on
a Mel-Temp (Mitamura Riken Kogyo.) apparatus using
open capillary tubes and is uncorrected. The solid state
Fourier transform infrared spectrum was recorded on a
Perkin Elmer Spectrum One (Ver. B) FTIR Spectropho-
Synthesis of 1,2-Bis (4-nitro benzoyloxy) ethane
To a pre-baked three-neck round bottom glass flask equipped
with a magnetic stirrer, reflux condenser and nitrogen inlet, a
solution of ethylene glycol (0.75 mL.; 13.47 mmol) and
triethyl amine (3.734 mL; 26.94 mmol) in 50 mL of anhy-
drous toluene was introduced. The solution was cooled to
1
13
tometer using KBr pellets. H and C-NMR spectra were
obtained on a Bruker 300 MHz NMR Spectrophotometer in
DMSO-d using teteramethyl silane as internal reference.
6
The data for the crystal structure analysis were collected on
a STOE IPDS-II diffractometer with monochromated Mo-
Ka radiation at 173 K. Data were corrected for Lorentz and
polarization effects. The structure was solved by Direct
Methods using SHELXS-97 [18], and refined by full-matrix
least-squares techniques using SHELXL-97 [18]. All
hydrogen atoms were localized from difference Fourier
maps, but refined using a riding model with fixed indi-
1
0 °C and p-nitrobenzoyl chloride (5 g; 26.94 mmol) dis-
solved in 15 mL of toluene was added drop-wise to it over a
period of 15 min. After complete addition, the mixture was
refluxed for 3 h under inert conditions. The resulting mixture
was then allowed to cool and excess solvent was evaporated
under vacuum. The solid obtained was filtered out, stirred
with distilled water for 1 h, again filtered and recrystallized
with ethanol to afford the pure crystals of 1,2-bis (4-nitro
benzoyloxy) ethane. Yield 85%, m.p. 136.4 °C. Elemental
analysis for C H N O (MW = 360) in wt% calc.
vidual displacement parameters [U(H) = 1.2 U (C)] with
eq
˚
Cmethylene–H = 0.99 A and C
˚
–H = 0.93 A.
aromatic
1
6 12 2 8
C = 53.33, H = 3.33, N = 7.77 and found C = 52.95,
-
1
H = 3.38, N = 7.92. FTIR (KBr pellet) in cm : 3112, 3079
aromatic C–H), 2958, 2856 (aliphatic C–H), 1720 (ester
C=O), 1608 (aromatic C=C), 1524, 1349 (NO stretch), 1263
Results and Discussion
(
2
The title compound (1,2-bis (4-nitro benzoyloxy) ethane)
was prepared by nucleophilic substitution reaction under
inert atmosphere created by dry nitrogen gas using Schotten–
Baumann conditions (Scheme 1). The reaction occurred
1
(
C–O stretch), 837 (p-C H bend). H NMR (DMSO-d ) in d
6
ppm) and J (Hz): 8.429 (d, 4H, J = 6.6, Ar–NO ), 8.297 (d,
2
6
4
(
1
3
4
H, J = 6.8, Ar–CO), 4.770 (t, 4H, CH O). C NMR
2
(
DMSO-d ) in d (ppm): 164.46 (2C, C=O), 150.75 (2C,
immediately at low temperature (10 °C) as Et N-HCl
6
3
aromatic C1), 134.94 (2C, aromatic C4), 130.84 (4C, aro-
0
(derived from hydrochloric acid produced in the reaction and
triethyl amine) was observed at once as soon as the solution
of 4-nitrobenzoyl chloride in reaction solvent was added
0
matic C3,3 ), 123.66 (4C, aromatic C2,2 ), 63.36 (2C,
CH O).
2
123

1
182
J Chem Crystallogr (2011) 41:1180–1184
O
C
drop-wise to the reaction flask. The low temperature was
needed to prevent the hydrolysis of ester group (O=C–O)
under alkaline conditions. The synthesized dinitro-diester
precursor was subsequently characterized by its melting
O N
Cl + HO CH2 CH2 OH
2
Dry toluene
1
13
point, elemental analysis, FT-IR, H and C-NMR spec-
3
h reflux
Triethylamine
troscopic studies. The results of these analyses are presented
1
13
in experimental section and the FTIR, H and C-NMR
spectra are displayed in Figs. 1, 2 and 3, respectively. The
observed values for carbon, hydrogen and nitrogen are in
good agreement with the calculated ones. The FTIR spec-
trum (Fig. 1) exhibited two characteristic bands due to nitro
O
C
O
C
O N
O
CH2
CH2
O
NO2
2
Scheme 1 Synthesis of the title compound
1
Fig. 2 H-NMR spectrum of
the title compound
13
Fig. 3 C-NMR spectrum of
the dinitro-diester
1
23

J Chem Crystallogr (2011) 41:1180–1184
1183
-
1
group at 1,524 cm
(asymmetrical stretching) and
(symmetrical stretching), respectively. The
ester group was characterized by a sharp absorption band at
for the synthesized compound with the atom numbering
scheme is depicted in Fig. 4. Crystal data and structure
refinement for the title compound are presented in Table 1
and the most significant bond distances and angles are
reported in Table 2. The compound crystallizes in the
orthorhombic space group Aba2 with cell parameters
-
1
1
,349 cm
-
1
1
,720 cm . The aromatic and aliphatic moieties in the
compound can be identified by the bands at 3,112,
-
,079 cm (aromatic C–H stretching) and 2,958 cm ,
1
-1
3
˚
a = 33.119(2) A, b = 8.1301(5) A, c = 11.9784(8) A,
˚
˚
2
,856 (aliphatic C–H stretching).
1
The H-NMR spectrum of the synthesized dinitro com-
3
V = 3225.3(4) A and Z = 8. The analysis reveals that the
˚
pound is consistent with the proposed molecular structure.
The signals associated with different aromatic and aliphatic
protons can be observed in the spectrum (Fig. 2). The
central O–CH –CH –O unit shows a partially eclipsed
2
2
o
conformation [torsion angle O2–C2–C3–O3 -59.4(2) ].
The dihedral angle between the two aromatic rings present in
o
the compound is 45.87(6) . The terminal nitro groups and the
1
3
C-NMR spectrum of the compound exhibited the signals
due to the presence of aromatic and methylene carbons
Fig. 3). The presence of ester group is evident from the char-
bridging ester groups present in the compound are almost
coplanar with the aromatic rings to which they are attached
(
o
[dihedral angles 9.50(18) for N1,O5,O6 and 4.08(23) for
o
acteristic signal at the farthest downfield (*164.46 ppm)
corresponding to the carbonyl carbon of ester group.
o
N2,O7,O8, and 4.7(3) for O2,C1,C11,C16 and O4,C4,C21,
o
C26 for 5.0(3) , respectively].
The synthesized dinitro-diester can be easily isolated as
crystalline material with a sharp melting point therefore its
molecular structure can also be characterized by single
crystal X-ray analysis, the most straightforward technique
to confirm the identity. The molecular structure obtained
Table 1 Crystal data and structure refinement for the title compound
Empirical formula
Formula weight
Temperature
16 12 2 8
C H N O
360.28
173(2) K
˚
0.71073 A
Wavelength
Crystal system
Space group
Orthorhombic
Aba2
˚
Unit cell dimensions
a = 33.119(2) A, a = 90°
˚
b = 8.1301(5) A, b = 90°
˚
c = 11.9784(8) A, c = 90°
3
˚
Volume
3225.3(4) A
Z
8
3
Density (calculated)
Absorption coefficient
F(000)
1.484 Mg/m
-
1
0.122 mm
1488
3
Crystal size
0.48 9 0.46 9 0.46 mm
Theta range for data collection
Index ranges
2.46 to 25.39°.
-39 B h B 39, -9 B k B 9,
14 B l B 13
-
Reflections collected
9532
Independent reflections
Completeness to theta = 25.00°
Absorption correction
1561 [R(int) = 0.0798]
99.8%
None
Max. and min. transmission
Refinement method
0.9461 and 0.9439
Full-matrix least-squares on F
1561/1/236
2
Data/restraints/parameters
2
Goodness-of-fit on F
1.049
Final R indices [I [ 2r(I)]
R indices (all data)
R
R
1
1
= 0.0320, wR
2
2
= 0.0692
= 0.0702
= 0.0333, wR
Absolute structure parameter
Extinction coefficient
-0.3(10)
0.0042(3)
Fig. 4 Molecular structure of the title compound with the atom
numbering scheme
-3
˚
0.139 and -0.120 e A
Largest diff. peak and hole
123

1
184
J Chem Crystallogr (2011) 41:1180–1184
˚
Table 2 Selected bond lengths [A] and angles [°] for the title
compound
crystal structure confirms that the terminal nitro groups are
accessible for further chemical modification.
N(1)–O(5)
1.221(3)
1.236(3)
1.470(3)
1.203(3)
1.329(3)
1.454(3)
1.493(3)
1.494(3)
1.490(3)
1.392(4)
0.9500
N(1)–O(6)
Supplementary Material
N(2)–C(24)
O(1)–C(1)
Supplementary data of the crystal structure and refinement,
like full bond lengths, bond angles dihedral angles, and
anisotropic displacement parameters, have been deposited
with Cambridge crystallographic data centre, CCDC No.
O(2)–C(1)
O(2)–C(2)
C(1)–C(11)
C(2)–C(3)
751826. These data can be obtained, free of charge, using
C(4)–C(21)
the link: www.ccdc.cam.ac.uk or from the CCDC, 12
C(12)–C(13)
Union Road Cambridge CB2 1EZ, UK, Fax: ?44-1223-
C(16)–H(16)
3
36033; e-mail: deposit@ccdc.cam.ac.uk].
O(1)–C(1)–O(2)
O(5)–N(1)–O(6)
O(5)–N(1)–C(14)
O(6)–N(1)–C(14)
O(8)–N(2)–O(7)
C(2)–C(3)–H(3B)
H(3A)–C(3)–H(3B)
O(4)–C(4)–O(3)
C(12)–C(11)–C(16)
C(12)–C(11)–C(1)
C(16)–C(11)–C(1)
C(13)–C(12)–H(12)
C(14)–C(13)–C(12)
C(14)–C(13)–H(13)
C(13)–C(14)–C(15)
C(13)–C(14)–N(1)
C(14)–C(15)–H(15)
C(26)–C(21)–C(22)
C(26)–C(21)–C(4)
C(22)–C(21)–C(4)
C(23)–C(22)–C(21)
C(23)–C(24)–C(25)
123.9(2)
124.0(2)
124.0(2)
117.5(2)
123.3(2)
110.3
Acknowledgments The authors are grateful to the Department of
Chemistry, Quaid-i-Azam University, and the Institute for Inorganic
Chemistry, University of Frankfurt, for providing laboratory and
analytical facilities.
108.5
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The synthesis of a semi-aromatic dinitro precursor, 1,2-bis
4-nitro benzoyloxy) ethane, in good yield allows access to
(
a synthon containing pre-formed ester linkages between the
aryl moieties and aliphatic spacers which can be used in the
preparation of soluble high performance polymers with
desirable physical and chemical properties. The X-ray
1
18. Sheldrick GM (2008) Acta Crystallogr A 64:112
1
9. Mohsin MA, Akhter Z, Bolte M, Butt MS, Saif Ullah Khan M,
Siddiqi HM (2009) J Mater Sci 44:4796
1
23